Anyone do a solid axle conversion here? [Archive] (2024)

Skyler

10th June 2003, 17:14

I thought that perhaps someone here in the swaps forum has converted to a solid (live) axle or has perhaps researched it a bit. I would like to pick up some knowledge or insight from anyone here. I am thinking along the lines of an 8.8 narrowed by moser with custom axles and a 4-link.

Thanks,
Skyler

Chris92

10th June 2003, 18:34

oh God! KNEW this would happen someday....

:ohno:

no to my knowlege, no one has yet butchered one of the best handling cars in the world... yet... wanna be the first? it would probably be easy.. but pointless? unless you tub it and make a drag car... and then there are much cheaper and more fruitful ways to go 1320 feet!

just my 2 cents

JohnB./CRUZ-MSL

10th June 2003, 18:41

Skyler

10th June 2003, 19:09

Originally posted by 91Miata:
unless you tub it and make a drag car... Bingo....we have a winner.

no one has yet butchered one of the best handling cars in the world Butchered? Transformed may be a better choice of words. Sorry this car is not "one of the best handling cars in the world". It is one of the cheapest good handling cars in the world. Lets face it, the car is very cheap, very light, and RWD based....I am not attempting to deface the Mona Lisa here. Just have some fun with what I like doing which is drag racing.

and then there are much cheaper and more fruitful ways to go 1320 feet!
Of course there is....that never stopped Mopar guys. Besides, I like this platform.

Skyler

10th June 2003, 19:16

Originally posted by JohnB./CRUZ-MSL:
...Nope, I don't know of anyone that did either. the Idea of most, is to build it to go like hell...straight, and around corners. I guess that you could do it..you would have to clip the rear end and tub it. But I am sure that if you put the time and effort in anything is possible. "Pro-Street-Monster -Miata"....hmmmm?
JohnB I talked to Moser about it, they said that they can take a stock 4-link 8.8 rear and narrow it, build custom axles for it, and rebuild the clutch pack for $600ish. Not a bad start. What I need is pointers and direction. Not "What the hell are you doing?" type comments.

Many drag cars have alot of money into their rear end assemblies, I may actually be building a somewhat cheaper drag car believe it or not 91Miata. But that is not the purpose of this thread. I just need good ideas and good direction.

Thanks,
Skyler Schmitt <--Never Road Races/Never AutoX's :D

Rich Wilkman

10th June 2003, 19:30

After chopping and tubbing those have got to be some really tiny axels! How small? How much room is left for your fuel cell?

-Rich

oldfart

10th June 2003, 19:43

Originally posted by Spooler:
Sorry this car is not "one of the best handling cars in the world". It is one of the cheapest good handling cars in the world. Lets face it, the car is very cheap, very light, and RWD based... [/QB]Your ignorance is showing. This IS the best handling car in the world, and it holds records to prove it. And it would make one of the worst drag cars in the world. If you want cheap, go to Ugo. Most 16 year olds can't afford a Miata.

There is no frame, the body is too short, it's inadequate for tubbing. The engine compartment won't accept a big block MoPar. To properly build a drag car from a Miata, you'd have to skin the body over a new cage and full frame to hook.

When you grow up, perhaps you can look at this car with a little different perspective and enjoy a little automotive pleasure.

:mad:Bob:mad:

Chris92

10th June 2003, 21:33

Hey Spooler, sorry didn't mean to offend you! I'm all for ANYTHING that makes you happy... but I think you can tell from my and Bob's comments, and they are based on (pretty much) the entire Miata community's affinity to keep the great handling at all costs... it's just not known as a drag platform.

BUT... if you LOVE the body style, and HAVE to have a drag car that looks like a Miata, then have fun... but I stand by my general feelings on it and really agree with Bobs...

I still want to say that I personally welcome you and any Miata guys anyway... even if I'm baffled!

If you do it, keep us posted... (all the way to time slips!) doh!

-Chris :D

MV8,Mstr ASE/A&P/FCC

10th June 2003, 23:34

http://www.members.tripod.com/CianciMotosport/id28.htm

With a sheetmetal 9 inch rear, a 2 speed powerglide, and a 4.3L v6 it ran a 9.44 at 145mph in the quarter. Full frame and cage.

Go for it.

brmx5fan

11th June 2003, 07:32

Originally posted by miatav8, Steve J:
http://www.members.tripod.com/CianciMotosport/id28.htm

With a sheetmetal 9 inch rear, a 2 speed powerglide, and a 4.3L v6 it ran a 9.44 at 145mph in the quarter. Full frame and cage.

Go for it. OMG :eek:

Brad

oldfart

11th June 2003, 08:07

Originally posted by miatav8, Steve J:
http://www.members.tripod.com/CianciMotosport/id28.htm
UNCLE! UNCLE!

Can you spell EXPENSIVE??

VERY NICE!

Bob

Chris92

11th June 2003, 08:47

I'd like to see what Sal Cianci does for exhaust routing... that could possibly open the door to Chevy Miata experiemnts..

Chris

Icehawk

11th June 2003, 09:18

Make up your mind Bob. :ohno:

I say go for it! So what, we all know the Miata isn't the best platform but is that really the point??? No, I don't think so. The Miata is not the best handling car, not even close. Put some work into it though, and yes it can hang. Same thing for drag racing. And btw, I am super not into drag racing - corners are my thing but who am I to tell others what to do? Nowhere does it say the Miata MUST be about handling.

No need for a big block anyways, a worked FE3 with a T60 should do 600hp... plenty I'd think.

Steveamnmn

11th June 2003, 10:05

Originally posted by miatav8, Steve J:
http://www.members.tripod.com/CianciMotosport/id28.htm

With a sheetmetal 9 inch rear, a 2 speed powerglide, and a 4.3L v6 it ran a 9.44 at 145mph in the quarter. Full frame and cage.

Go for it. With the 4.3 V-6 running 9's, it's kind of neat to know that you can unbolt it and drop a Chevy small block V-8 in there as a simple, bolt-in installation. Same, tranny, mounts, etc.

The new, 600 HP naturally-aspirated 427 ci World Products small block crate engine would probably work...

8's in a Miata? Zoom Zoom.

Steve A.

Skyler

11th June 2003, 10:36

Originally posted by oldfart:
Originally posted by Spooler:
Sorry this car is not "one of the best handling cars in the world". It is one of the cheapest good handling cars in the world. Lets face it, the car is very cheap, very light, and RWD based... Your ignorance is showing. This IS the best handling car in the world, and it holds records to prove it. And it would make one of the worst drag cars in the world. If you want cheap, go to Ugo. Most 16 year olds can't afford a Miata.

There is no frame, the body is too short, it's inadequate for tubbing. The engine compartment won't accept a big block MoPar. To properly build a drag car from a Miata, you'd have to skin the body over a new cage and full frame to hook.

When you grow up, perhaps you can look at this car with a little different perspective and enjoy a little automotive pleasure.

:mad:Bob:mad: [/QB]Here we go.... :rolleyes: The ignorance comment was not neccessary. Yes it breaks records for handling when really modified. What exactly do you consider the "worst drag car in the world"? It goes fast in a straight line....what are you trying to say? I am not going to put a Mopar big block in the car, I am going to use the miata engine. I was responding to the comment made by 91miata about there being cheaper platforms for a drag car. I don't know how much you got ripped off paying for a miata, but I got the car for $2800. Most 16 year olds can swing that. However, I am not 16. I have talked to several local big drag racing outfits that told me that it would actually be pretty easy. One of them just converted over a Sunbeam Tiger to a similar setup which is yielding 1.4 short times all day. Perhaps when you grow up "oldfart" you may be slightly less narrow minded and consider the fact that your perspective is not the only perspective.

[ 11. June 2003, 10:54: Message edited by: Spooler ]

Skyler

11th June 2003, 10:51

Originally posted by Icehawk:
Make up your mind Bob. :ohno:

I say go for it! So what, we all know the Miata isn't the best platform but is that really the point??? No, I don't think so. The Miata is not the best handling car, not even close. Put some work into it though, and yes it can hang. Same thing for drag racing. And btw, I am super not into drag racing - corners are my thing but who am I to tell others what to do? Nowhere does it say the Miata MUST be about handling.

No need for a big block anyways, a worked FE3 with a T60 should do 600hp... plenty I'd think. I am actually going to stay with the BP engine. Goals for the car are to eventually get into the 10's using minimal HP with the ability to drop the clutch of the line holding about 5-7psi boost using a 2 step and get a 60ft in the 1.4-1.5 range with ease. That said, I want to build a rear frame to support the Ford 9 inch. This will all be done in my shop with the assistance of local draggers and friends. Right now what I need help with is design of the frame to mount up a typical true 4-link. A Mustang for exaple does not have a true 4-link as the upper control arms don't run parallel which creates somewhat of a bind but is still decent for hooking.

JohnB./CRUZ-MSL

11th June 2003, 12:13

oldfart

11th June 2003, 14:29

Originally posted by JohnB./CRUZ-MSL:
Easy guys...it's only a forum.... GeeWhiz! I even uncled! That drag car address was a very nice execution of a sport that cost me dearly in bunches and bunches of cash. Yah, lots of trophies and glitter, and it was lots of fun when acceleration was the biggest thrill in my life, so if that's what turns your crank, I'm glad we both appreciate the appeal of the Miata. I can see the money that was spent on that car, and know what it takes to make a Miata turn 9's. It doesn't happen the first time, for sure. I appreciate your ambition and would not restrain anyone from their dreams. Likewise, having seen the other side of the experience, my friends and I would not want to go there again. Maybe we just outgrew it, or maybe I see my retirement funds having been reduced by what no longer turns my crank. I had the 650 HP in my drag car.

I won't rain on your parade, but by the same token, I won't change my opinion. We are all entitled to that. I just hope you don't reach the same conclusions I have, when you are done.
A $2300 investment in the car is immaterial to total cost, but may be critical to final value.

Bob

Chris92

11th June 2003, 16:25

I paid $5000... should I return it? haha

Cool u got a deal at $2800... keep us posted

Chris

[/QB][/QUOTE]Here we go.... :rolleyes: I was responding to the comment made by 91miata about there being cheaper platforms for a drag car. I don't know how much you got ripped off paying for a miata, but I got the car for $2800. [/QB][/QUOTE]

JohnB./CRUZ-MSL

11th June 2003, 17:59

skipsV8

11th June 2003, 18:05

I was thinking of converting my car to a Hovercraft. I found inflatable kiddie pools at K-Mart the other day I could duct tape one on and go for the nearest lake. Ha Ha

Later

Skip

davidb72

11th June 2003, 20:17

Originally posted by skipsV8:
I was thinking of converting my car to a Hovercraft. I found inflatable kiddie pools at K-Mart the other day I could duct tape one on and go for the nearest lake. Ha Ha

Later

Skip Would you be running a solid axle on your hovercraft???

I think Jeep is making some Aluminum center sections if you are looking to save weight.

oldfart

11th June 2003, 21:45

oldfart

11th June 2003, 21:55

JohnB./CRUZ-MSL

11th June 2003, 21:57

..you guys are brutal, This is how us early "dark side folks " were treated by the four cylinder faithful...early on. If the guy wants a drag car...let him build a drag car !

I remember some saying ...Why would you ruin a perfectly good sports car...and drop in that big v8??? Well I haven't found one of the faithful that drove it..or in it, that did not understand why...after the ride. His money..his car...his straight axle ????

JohnB

rsa

11th June 2003, 23:07

Skyler,

What are you thinking about for lengths of the links? :) Numbers I've seen are in the ballpark of 18" top and 14-15" bottom, but they can of course vary from that. Is there enough room for the links in front of the rear axle of the Miata without a lot of surgery?

As an aside, you mentioned Moser (Engineering). I was saddened to find out that the owner and founder has recently died in an airplane crash, along with several others. Story of the accident (http://www.moserengineering.com/TopStory.htm). Moser has also made a statement about how the company is prepared to handle the loss, from a business perspective (http://www.moserengineering.com/).

Stu

oldfart

12th June 2003, 02:12

Originally posted by rsa:
Is there enough room for the links in front of the rear axle of the Miata without a lot of surgery?
Stu OK, Enough fun. Look at the subject on "wheel hop (again)" pages one and two. I outlined the four link system there. The upper links are dictated by the space and the bracket location on your straight axle. The bottom link can be as long as you want, three feet is fine. The longer it is the less potential problems you will have. All of the required parts are listed along with the prices. Weld your fittings together and use chromemoly tubing. So long as the links are parallel and horizontal they will not bind. You will spend about $200+ on these parts to do it right. Of course, one could try cheaper materials. There is more than one way to spell BROKE, BROKEN, BREAK. But that comes easier in time.

Enjoy.
Bob

Skyler

12th June 2003, 02:41

Yes I was saddened to read that story on their website as well.

After further review of the matter I am now considering a ladder bar setup. It will be a little more simple to setup. I would have to add a ladder bar cross member welded between the frame rails which gives me the mounting point for the ladder bars up front. the rear of the ladder bars will obviously mount to the axle tubes. This leaves the mounting of either coil over shocks or 3-way adjustables. These should be able to be mounted to the car with minor mods like reinforcing the SF at those areas if necessary. The ladder bars are in the 33 inch range.

To the other folks, please avoid hijacking this thread as the things that you have said have been useless so far. :rolleyes:

oldfart

12th June 2003, 07:12

Originally posted by Spooler:
the things that you have said have been useless so far. The "frame rails" in the stock Miata are about 16 gauge sheetmetal. Ladders will require a little more thought, i.e., my comment about the full cage and frame for 9 seconds. They won't let you on the track without it after your first 10 secound run. Useless is as useless does. The information is more valuable than you realize.

Bob

wsl

12th June 2003, 08:15

A solid axle will give you the best performance and durability for drag racing, but don't discount what can be done with an IRS set-up. Our stock 302 powered Miata can do 1.6 sec. 60' times all day long with no wheel hop. After getting a pair of axles from Martin, it has been a bullet-proof set-up at these power levels.

The direct-port nitrous will be tested this summer to help with top end, and a 347 is planned for the winter. Will it break something? Probably, but why would it bother any of you? It's his car, his money, his time. Sorry I can't offer any help, but good luck with your project.

-Scott
V8 Miata (http://www.v8miata.homestead.com/)

Skyler

12th June 2003, 09:32

Originally posted by oldfart:
Originally posted by Spooler:
the things that you have said have been useless so far. The "frame rails" in the stock Miata are about 16 gauge sheetmetal. Ladders will require a little more thought, i.e., my comment about the full cage and frame for 9 seconds. They won't let you on the track without it after your first 10 secound run. Useless is as useless does. The information is more valuable than you realize.

Bob Actually, all that they told me to add to the car was an arm bar to make a 10 second pass after inspection of the car. If the crossmember requires reinforcements at the frame rails for welding....then thats what I will do. No big deal. However, the crossmember is not only welded at the frame rails, it is continously welded on both sides. Do you think that this would be sufficient? Or do you think that further plate reinforcements would be required at thos areas?

oldfart

12th June 2003, 10:55

The body panels are quite a bit thinner than the frame rails and silver soldering might be a more applicable process than welding (Ha!).
I understand what you are talking about as I've done it on regular cars like the '95TA. That was quite a bit heavier sheetmetal, received much more frame rail strengthening (10 ga. box tubing full length) 10 ga. tunnel support, cross-braces for ladders and they still bend it on ten seconds.

Why do I care? "Do unto others as you would have them do unto you." I wish someone had told me what I'm talking about when I started my project. It was a bunch of people in the business that were selling me services and parts! I used to think I knew enough. Now I think I'm wiser than I used to be, but still not smart enough to keep my mouth shut. I certainly don't have all the answers, but I have an opinion on most everything. This is fact, not opinion: You can get hurt with a lot of power and a car that could break. It's not just the money, although that has become important to some of us.

The drag car in the address above is an excellent, excellent execution of a proper build: how to do it right and not get killed. His times are proof that a 9 sec. time can be achieved. I think NHRA rules require a four or five point roll bar cage for 10 seconds, and a full six point cage, harness and much more for 9 seconds, and at some point, perhaps 7 sec.? a parachute. Suggest you read the NHRA rule book. Any track that lets you run with less is a very dangerous track as they can't get insurance. They may just be assuming that you will run an 11 or 12, and they are usually pretty good at guessing first run times.

I'd be curious to see the data run on computer analysis of a Miata engine turning 9 seconds. What? 450 HP? 500 HP? Huge difference between 12 sec. and 9 sec. Anyone??

I haven't seen the report of a 400HP Miata hitting 200MPH on a four mile track yet! Did you do it? I'm happy at 65MPH (in under 4 sec.)

Bob

Skyler

12th June 2003, 11:28

Icehawk

12th June 2003, 11:29

MV8,Mstr ASE/A&P/FCC

12th June 2003, 16:40

Skyler

12th June 2003, 17:06

oldfart

12th June 2003, 19:31

MV8,Mstr ASE/A&P/FCC

13th June 2003, 00:40

Skyler

13th June 2003, 02:30

oldfart

13th June 2003, 06:26

Originally posted by Spooler:
How far All the way?Yes. I'd find a main chassis bolt and anchor it about where the back of the engine is, or the front suspension is. The new Miata's have a new major cross-member (cradle) added there too.

All this extra bracing is adding weight that is going to kill your efforts for 9 seconds, which takes us back to the original discussion..... Gut the sucker and put in a tube cage and frame, skin the body back on and go lightweight. A little more work, but if you really want 9 seconds, this is how it's done. (in my opinion). You have to add the cage anyway.

Once you get over the sad*stic humor of my picking on you, you'll come to the same conclusions. :p

Bob

Icehawk

13th June 2003, 07:45

I don't think full tube frame is necessary, like I said Ric & Marc are hitting high 10s on stock framed Miatas - to the best of my knowledge neither have more than cages for bracing either.

What I would do is get a serious cage that tied into as many places as feasible. Some underchassis bracing... and see how it goes.

Skyler

13th June 2003, 09:39

Steveamnmn

13th June 2003, 10:17

Originally posted by Spooler:
Well, with the removal of the PPF, stock suspension, fuel tank, and the installation of the additional bracing, I don't think weight will be added necessarily but rather be about the same. I think the necessary component changes and bracing will increase weight substantially over stock. Having removed the PPF, subframes, rear differential, suspension arms, etc. out of my stock Miata, I was amazed by how remarkably light all these components are. The aluminum alloy PPF, for example, is so light that you can pick it up with one finger.

A strong, straight axle assembly will be much heavier than what came out of the car. Just a wild guess, but maybe another 50 - 75 lb. Coilovers would help to minimize overall weight with such a conversion. You could/should probably add something like another 100+ lb. of steel bracing for a really stiff (and safe) drag chassis.

Even if the car (minus engine/transmission) came in at 200 lb. more than a stock Miata (minus engine/transmission), it would still have a substantial weight advantage over most everything else running a similar horsepower engine. So I'm certainly not saying it can't be done.

The Cobra Kit Cars are similar in many ways to the V8 Miata conversion. The Cobra manufacturers often offer their cars with your choice of a straight axle setup or an IRS setup. The IRS is an optional upgrade. The straight axle makes the best pure drag car, and the IRS makes a smoother riding, better handling all-arounder. Different strokes for different folks.

FWIW, there are several '03 Mustang Cobras around with modified engines (big boost, etc.)that are running 10's in the 1/4. Some are doing this with the IRS setup. One car reported on in the latest issue of FF&MM magazine actually broke into the highest 9's on an IRS in one of the sanctioned, all-Ford drag meets. These cars weigh 1000 lb. more than a V8 Miata conversion, so I don't see why an IRS setup couldn't be setup, strengthened, and tuned to deliver 10's in the Miata.

I'm not suggesting that the IRS is a better drag setup, because it's not. Just that you have the choice of a better all-arounder that can still tear up the stip, if that were your preference. Martin (Panache) can make the hanger assembly for the 8.8" Ford IRS pumpkin; it's available in aluminum if you want to save weight. He also has axles, but for a 10 second car you might want to have custom CV axles built to match the application. You'd probably have to relocate the bottom mount on the rear coilovers to make clearance for a bigger outer CV assembly.

With proper chassis mods (bracing for strength and torque transfer, proper spring and shock rates biased more towards strip use, detachable front sway bar, etc) I think a viable IRs street/strip setup could be created. Not to discourage you from the straight axle if that's what you want. It wouldn't be my preference, but that doesn't mean it shouldn't be yours.

Steve A.

Marc - 460hpMiata

13th June 2003, 10:23

I'm going to try and hit low 10s with the Miata Rear diff.. I still have not installed the RX7 setup..

I did make a comment to a friend that I may put a 8.8 or 9" setup in next year.... But who knows.. I like knowing I'm racing a Miata with Miata parts...

We shall see... But I support any Miata which goes fast, especially when they are still using the 4 banger motor.. (Sorry guy, I do think the 5.0s are cool)

oldfart

13th June 2003, 10:50

Skyler

13th June 2003, 11:09

oldfart

13th June 2003, 12:39

Skyler

13th June 2003, 14:57

It will be driven to the track, run a few 10's on ET Streets, turn around and drive home. That is the goal.

Oh yeah, the Mustang guys are doing 9's on the 8.8" rear now with doubled up clutches and upgrade axles. I think I will be fine.

Steveamnmn

13th June 2003, 19:13

I agree, a properly built and reinforced 8.8" ought to be more than adequate for 10's in a light weight roadster. It's usually the axles that fail in these when the design limits are exceeded, rather than the ring and pinion. Maybe run an air locker so you you have an effective spool on the strip and differentiation on the street?

Steve A.

oldfart

13th June 2003, 19:30

JohnB./CRUZ-MSL

14th June 2003, 20:51

...the 450 hp level is like braking the sound barrier in the miata chassis. With the independent rear suspension..it is a work out to get the car to et...the sixty foot area becomes an adventure. I used a set of drag radials...and even with a second gear lauch the tires unloaded in third gear...and went up in smoke until fourth gear! The straight axle will help...but the car is still a light weight. It will be a pretty wild ride with wrinkle walls and that good ol short wheel base. The good thing...if you are going after it without the v8 torque..life may be a bit better...

The independent rear is a great all around set up...except the drag strip !
Good luck
JohnB

oldfart

15th June 2003, 05:41

JohnB./CRUZ-MSL

15th June 2003, 06:48

....450 hp...2300-2400 pounds...short wheelbase !

I have the wheaties to go high tens...but with some very serious traction only. I would guess that wrinkles...and only wrinkles will work on mine. The independent suspension is too inconsistent for optimum traction , along with the light weight. But even on a straight axle...I dunno if I could get there.

I launched in second...had a terrible 60 foot time (2.023)...went 11.87 at 129 mph ! That was the best Et...and 60 foot time of the day. It hooked in second..then unloaded...then smoked all the way through third ? And this was on drag radials. The MPH says yes ! The 60 foot times say no way !

Only wanted to see how fast the trap speeds would be...mine is NOT a drag car...just a healty street'r...but for sure it is not a ten second car in it's present form. And I doubt very seriously that it ever will be ! I didn't build it with that in mind. But I do feel that the one way to get all of what I have to the pavement...wrinkle walls would be the best, and only way to make it work.
JohnB

JohnB./CRUZ-MSL

15th June 2003, 06:52

oldfart

15th June 2003, 08:08

JohnB./CRUZ-MSL

15th June 2003, 09:26

I think you are right! I had some visions of grandeur, putting a 315 under mine, with the home depot flair, might get me into the real world of traction. NOT ! It is a weight issue. They would help...but no cigar !

I remember seeing a 650 hp stock car(winston cup) run at one of the local drag strips...it went into the 10's...barely ! Even with the rather wide...large..road race slicks...it was traction limited at the 60 foot mark ! It ain't all about width of the rubber. It is suspension...tire compound...weight ...power...wheelbase, and most important "Z_DRIVER"
JohnB

JohnB./CRUZ-MSL

15th June 2003, 09:53

...I had a 86 SVO Mustang...v8 converted, with a 306/Vortec combo. It was in the area of 525-550 HP to the rear wheels. It was actualy set up for street/and road racing...

Id did manage the 10's...but it had some traction aids. Namely "wrinkle" wall tires. And a three link set up, by griggs. The three link and tires made a night and day difference. Prior to that...it would run mid elevens, with 10 inch M&H slicks. But the wrinckle tires really hooked ! I must say that the top end ride was "different" ! The tires gave the car squirrely feeling at 120 plus. But they do work ! And the car was a 3100 pound chassis.

JohnB./CRUZ-MSL

15th June 2003, 10:00

Steveamnmn

15th June 2003, 11:09

Originally posted by JohnB./CRUZ-MSL:
If you had 450hp and the assosiated torque. A launch from 5000 rpm, with the wrinkle tires...I would believe the 2300 pound , short wheel base car would be carring the front wheels ! With the light weight, short wheelbase, plus enough HP and traction to go 10's, I agree that the car will be saving significant tread wear on the front tires.

That's one reason why I suggested the air-locker instead of a conventional limited slip. When you drop the hammer, there may be just enough slippage in the posi as the clutches hook up that one wheel pulls harder/faster than the other, which throws the car off of a straight line. If you carry the wheels for 30 feet or so, it can be very inconvenient to be be pointed any way other than straight when they touch back down...especially with the short wheelbase car. You could end up paying an unexpected visit to your competitor's lane, car or even the track wall if you don't get a straight launch. At best, your ET suffers.

A straight launch happens from a good, properly set-up and adjusted chassis and rear tires turning exactly in sync. (Keep the tire pressure balanced, too). I wouldn't trust even a modified Trac-Loc for this level of power application and abuse. An Eaton with the carbon fiber clutches could probably have the spring preload increased enough to handle this combination of car weight/shock load, but then it would probably be noisy, chattering, and irritating in street driving. Of course, one shouldn't expect a 10 second car to have the same civility as a 13 second car. But the locker does solve that particular dilemma.

Steve A.

oldfart

15th June 2003, 14:25

Originally posted by Steveamnmn:
[QUOTE]Originally posted by JohnB./CRUZ-MSL:
"]If you had 450hp and the assosiated torque. A launch from 5000 rpm, with the wrinkle tires"... why I suggested the air-locker instead of a conventional limited slip. When you drop the hammer, there may be just enough slippage...
I wouldn't trust even a modified Trac-Loc for this level of power application and abuse. But the locker does solve that particular dilemma.
Steve A. Steve, I usually believe and enjoy everything you say, but I think you're wrong here. I drag raced a big old heavy '95 TA with 650 HP and a Moser 4:11 rear, Moser axles with Hot Rod case and STOCK 9" posi, also with one extra disk. If that was ever to give a problem, it would there. Well over 300 trips down the asphault with lotza times in the tens. Needless to say, it didn't lift....just wrinkles. DOT's ran twelves like they were Iraqii oil slicks instead of tires. If a stocker posi will push that hog to those times it will certainly push this little oinker! He CAN'T get the big wrinkles under the car, so the question of hooking is mute. The lifting is a joke! If you can't bounce it off the ground it won't go up and definitely not without the wrinkles.

Bob

heliumrush

15th June 2003, 14:32

Originally posted by oldfart:
Originally posted by Spooler:
It seems like what is being said is to either back-half the car, or use IRS. You are right in that the rigid straight axle, like an 8" would make the best drag car in the 450 HP range. 500 you'll need a 9". The front end gets 90/10 shocks and loaded springs with a raised front in order to get the best weight transfer at launch. That lifts the car at launch and throws the weight to the rear wrinkle slicks and it rockets. To enjoy the car on the street, that type front end doesn't work, the stiff rear end doesn't work, and the engines are usually so tweeked that the don't travel over a couple miles very well. Nitro and alchohol are not street fuels. Sacrifices have to be made to optimize either use. To compromize will reduce performance on both. You could take a look at adjustable air ride, adjustable coilovers, multiple sets of wheels, quickchange rearend, bypass SC, nitrous oxide, adjustable controller ECM, MSD ignition and black box, then you can switch back and forth. That's what I ended up doing on my TA. And that's where the money went. Find another bargain for $2800 and leave one of them alone. It's cheaper.
Bob [/QB]Ric Stephens. Ran a 10.9@125 on worn out BFG drag radials, Ford 7.5 inch IRS setup. Stock 1.8L engine, Stock 5 speed. He was putting out around 400 RWHP at the time.

Personally I wouldn't go with a soild axle unless you planning on putting down over 600 RWHP and plan to run some 8 second passes. Ideally the RX-7 turbo II rear end is probably the easiest bolt up deal for the rear end. Only a front mount needs to be fabed up. Down side is you don't get the the gearing selection and cheap diffs as you do with the Ford parts.

If your not building a Pro Import drag car, I wouldn't go with the soild axle. The TII or Ford IRS 7.5 should do you just fine.

Skyler

15th June 2003, 15:05

Skyler

15th June 2003, 15:15

Chris92

15th June 2003, 15:17

What was Ric running for a rear diff? Torsen? RX7?

[/QUOTE]No I haven't drag raced before. Just thought it would be fun to do a bunch of fun to do all this work and see if I liked it. On a side note, Ric has already went high tens on stock motor, IRS, and drag radials. Watch what you say. ;) [/QB][/QUOTE]

Skyler

15th June 2003, 15:26

Originally posted by mbeaver (heliumrush):
[QUOTE]
Personally I wouldn't go with a soild axle unless you planning on putting down over 600 RWHP and plan to run some 8 second passes. Ideally the RX-7 turbo II rear end is probably the easiest bolt up deal for the rear end. Only a front mount needs to be fabed up. Down side is you don't get the the gearing selection and cheap diffs as you do with the Ford parts.

If your not building a Pro Import drag car, I wouldn't go with the soild axle. The TII or Ford IRS 7.5 should do you just fine. Well, I want consitency out of launching the car. This means launching off boost from a two-step by side stepping the clutch at about 6000rpm on slicks with absolutely no worries whatsoever. Do you think that is possible with the stock IRS with a TII rear? After conversation with Ric, we both came to the conclustion that even if the TII rear held up to this treatment for a period of time, the rest of the suspension would not.

Skyler

15th June 2003, 15:29

oldfart

15th June 2003, 16:31

[QUOTE]Originally posted by Spooler:
Do some reasearch

Are these wrinkles? If so, I'm willing to admit that I've learned something new. No shorts, though! And I'm 17 going on 61.
Bob

JohnB./CRUZ-MSL

15th June 2003, 21:54

You would be asking an awful lot from those axles? Even if it is the Ford unit...and I would also question the Re splined hubs? If it were my bottom sitting in that proposed 10 second seat...I would not be too eagar to drop the clutch at 6000 rpm...

Just a couple of my pennys..
JohnB

rsa

15th June 2003, 22:15

Originally posted by Spooler: It seems like what is being said is to either back-half the car, or use IRS. There has to be a medium between those to (italics mine).Spooler,

As medium ground, how about swapping in a narrowed Mustang four link rear end, suspension and all? You'd be starting with an adequate design that's reasonably compact. It would at least require fabricating mounting points for the forward portions on the four control arms and for the shock and spring uppers. It certainly reduces the engineering challenges of designing and setting up a four link from scratch.

For drag racing, the compromises of the factory suspension can be mitigated somwhat by replacing the stock rubber control arm bushings with polyurethane bushings or spherical bearings (at the expense of aggressive cornering ability).

And for cornering, there are proven upgrade paths for the Mustang suspension including adding a torque arm and Panhard bar (which means you can lose the upper control arms) or even a Watts link setup. You do know the 1998 and up Crown Vic rear ends use a Watts link...

Stu

JohnB./CRUZ-MSL

15th June 2003, 22:22

Skyler

16th June 2003, 01:29

Originally posted by oldfart:
[QUOTE]Originally posted by Spooler:
Do some reasearch

Are these wrinkles? If so, I'm willing to admit that I've learned something new. No shorts, though! And I'm 17 going on 61.
Bob only a fraction of drag cars use wrinkle walls slicks. in that post you said that only 29" slicks were made. nothing else.

Skyler

16th June 2003, 01:38

Originally posted by rsa:
Originally posted by Spooler: It seems like what is being said is to either back-half the car, or use IRS. There has to be a medium between those to (italics mine).Spooler,

As medium ground, how about swapping in a narrowed Mustang four link rear end, suspension and all? You'd be starting with an adequate design that's reasonably compact. It would at least require fabricating mounting points for the forward portions on the four control arms and for the shock and spring uppers. It certainly reduces the engineering challenges of designing and setting up a four link from scratch.

For drag racing, the compromises of the factory suspension can be mitigated somwhat by replacing the stock rubber control arm bushings with polyurethane bushings or spherical bearings (at the expense of aggressive cornering ability).

And for cornering, there are proven upgrade paths for the Mustang suspension including adding a torque arm and Panhard bar (which means you can lose the upper control arms) or even a Watts link setup. You do know the 1998 and up Crown Vic rear ends use a Watts link...

Stu I am either looking at a four-link or a ladder bar setup. I like the idea of using the four-link in the miata because it uses less space and provides an infinitely adjustable instant center. Although the ladder bar setup may be more simple and almost as effective, I am no longer sure that there is enough room and clearance to carry the ladder bars as far foward as they need to be.

oldfart

16th June 2003, 05:45

Originally posted by Spooler:
I am no longer sure that there is enough room and clearance to carry the ladder bars as far foward as they need to be. [/QB]Four-links will offer linear forces to anchor points which are basically sheetmetal, but might require less to reinforce for the tension on top link and shear (bottom link) loads to be applied than the directional lift forces of a ladder bar. Forces applied from four links might make it harder to transfer weight rearward, due to body flex.

Also, keep in mind that the top link would anchor directly behind your left hip and just a couple inches away. Not a real good situation unless it's well thought out. Thought I'd mention that "spearing" potential. Wouldn't want you to get the point.

Bob

heliumrush

16th June 2003, 06:00

Originally posted by oldfart:
[QUOTE]Originally posted by Spooler:
Do some reasearch

Are these wrinkles? If so, I'm willing to admit that I've learned something new. No shorts, though! And I'm 17 going on 61.
Bob I guess you been out of the scene for a while. Ever since the import drag racing scene took off you can buy 22 inch drag slicks now.

Skyler

16th June 2003, 12:06

Originally posted by oldfart:
Originally posted by Spooler:
I am no longer sure that there is enough room and clearance to carry the ladder bars as far foward as they need to be. Four-links will offer linear forces to anchor points which are basically sheetmetal, but might require less to reinforce for the tension on top link and shear (bottom link) loads to be applied than the directional lift forces of a ladder bar. Forces applied from four links might make it harder to transfer weight rearward, due to body flex.

Also, keep in mind that the top link would anchor directly behind your left hip and just a couple inches away. Not a real good situation unless it's well thought out. Thought I'd mention that "spearing" potential. Wouldn't want you to get the point.

Bob [/QB]That would depend on the positioning of the upper link. On mustangs, the upper link is mounted much closer to the pumpkin.

oldfart

16th June 2003, 12:44

Originally posted by Spooler:
[/QB]That would depend on the positioning of the upper link. On mustangs, the upper link is mounted much closer to the pumpkin. [/QB][/QUOTE]

Ahh! VERY good idea! Kinda like what GM and Miata did with the torque arms. That would make a better lift, as that is the function in the Miata, to lift the engine, i.e., no rear trans mount. It's rigid all the way to the front motor mounts. If the lower links go 3 or 4 feet up the frame rails and the uppers go to the trans as rigid torque arms (ladders) where there is room in the tunnel I think you'd be better than anything I've read so far! That would be the compromise you spoke about, and a much better solution.

Do any of those Ricer tires have wrinkle walls????? They all look DOT based to me. All I ever see is spinning tires and lotza smoke. Sorry, I can't come to call a DOT tire a slick. It's a bauldy to me. Fat snow tires run about as well. Wrinkles hook.

Juan OLD FART

wsl

16th June 2003, 14:48

All this talk about an IRS not being reliable for drag race is very educational. Good thing I didn't know all this before our V8 Miata began putting down 1.5-1.6 sec. 60' times (about 35 runs to date) with Martins axles and an independent 8.8". Not saying a solid axle is not better, but the configuration we are running is working. Period.

The car did break one homemade axle early during testing, but that was it. Car ran on 24.5/8 R13 MT ET Drags on old BMW alloy's. No top end on the current engine limits 1/4 times to a best 12.4 around 108mph. Not the fastest (yet), but the launch is perfect and straight every time.

No times here, but you can see the launch in the video (http://www.v8miata.homestead.com/files/cecilno1.wmv)

BTW our drag car also won E MOD this past weekend at the local autox with different tires and shock settings. And yes, there was more than 1 car entered.

-Scott

oldfart

16th June 2003, 16:50

wsl

16th June 2003, 19:46

The link works fine for me, anybody else having problems?

Try clicking the link on this page (http://www.v8miata.homestead.com/video.html), it's the second video listed. The first one is ATCO NJ, the third video is the broken axle.

-Scott

JohnB./CRUZ-MSL

16th June 2003, 22:33

...Do not get me wrong.The miata will launch with the independent rear. But now add 400 plus HP and some serous tires...Then I think it will not be as consistent as the straight rear axle set up.

...I can't speak from total expierence, only a handfull of passes made with my car. And that was on some tired drag radials. Either I smoked the clutch...or it was the tires. Not a real good test.

But I can speak with some knowledge of A few big block Mid year Corvettes. They were of the independent rear variety...and with tires of the era...they were not the best set up as the power grew. This is when none( try it today !) cared about matcing numbers...but the independent rear was the same issue...you began to hit the wall at the low eleven seond ET mark. The rear would squat...and the geometry would change...and you lost the foot print. Wrinkle tires helped...but the bite was too good...the rears would let( axle shaftes too) go...or you headed towards the tree..or guard rail. The straight axle was added to more than a few of these. Not mine ! I was content ...and it was the only car I had !

The independent rear will work ! But will it be the best set up for what you want...??

JohnB

Skyler

17th June 2003, 10:31

Originally posted by wsl:
All this talk about an IRS not being reliable for drag race is very educational. Good thing I didn't know all this before our V8 Miata began putting down 1.5-1.6 sec. 60' times (about 35 runs to date) with Martins axles and an independent 8.8". Not saying a solid axle is not better, but the configuration we are running is working. Period.

The car did break one homemade axle early during testing, but that was it. Car ran on 24.5/8 R13 MT ET Drags on old BMW alloy's. No top end on the current engine limits 1/4 times to a best 12.4 around 108mph. Not the fastest (yet), but the launch is perfect and straight every time.

No times here, but you can see the launch in the video (http://www.v8miata.homestead.com/files/cecilno1.wmv)

BTW our drag car also won E MOD this past weekend at the local autox with different tires and shock settings. And yes, there was more than 1 car entered.

-Scott Thanks a BUNCH for your input on the matter. I am assuming you are using the Lincoln 8.8? What is your power level and how consistent are your 60ft.? Nice vid BTW! :D Now saved to my hard drive!

Thanks,
Skyler

wsl

17th June 2003, 10:54

The 8.8 is from the new Cobra. It's the aluminum unit with a Torsen, Type 1 IIRC. 60' times are very consisitant now that we figured the proper way to launch it. It could even make a nice bracket racer with a better driver.

A little N20 in the upper gears would make it quite a ride.

Gratuitous (big) tire smoking (http://www.v8miata.homestead.com/drag2.html) image.

Skyler

17th June 2003, 11:05

wsl

17th June 2003, 11:21

The only time slip I have with me is the following:

60' - 1.685
330 - 5.070
1/8 - 78.94
MPH - 87.01
990 - 10.272
1/4 - 12.473
MPH - 104.54

The car never did better than a 12.4, and the highest MPH was around 109. I should have more numbers after some runs this summer. The 12-15 runs in Gainesville were the 1.5-1.6 sec 60' times, but only managed 12.5-12.6 times. The MPH creped up a little, but never more than 110. There's more in the car, we just need to find it.

Nothing special for the launch, hold it at 4,400-4,600 rpm and side step the clutch. The MT ET's hold pretty good in the box, but can spin down track. The clutch is a Ford Motorsport unit.

-Scott

Skyler

17th June 2003, 12:46

wsl

17th June 2003, 13:35

Mike Flores

18th June 2003, 14:31

wsl

18th June 2003, 17:10

Did you ever get a chance to weigh your car for weight distribution?

Not yet. The local SCCA region usually brings the scales to the autox, but they didn't have them last time. Hopefully later this summer it will get weighed.

JohnB./CRUZ-MSL

21st June 2003, 16:53

The weight disribution must be optimum...great 60 foot times !

What is the 302 set up? Heads...cam intake etc? Seems to be nosing over early

Al English

22nd June 2003, 22:45

I have given a fair amount of thought to changing my car to a conventional rear axle, and not for drag racing. The car has to be Ginsued up quite a bit to make it happen, but I've destroyed hardware worth a lot more than my Miata.

Early in this thread there was talk this would wreck the car's handling. That is not a given. From looking at the Miata rear suspension it doesn't look to have enough camber gain to compensate for body roll. That's not a problem with a straight axle. The primary drawbacks of a straight axle are reduced roadholding on rough surfaces and some increased in unsprung weight. I've always felt the Miata rear suspension is a little nervous. A straight axle could cure that and also eliminate the acceleratiion problems inherent to a high powered Miata. Beyond that I believe, using an aluminum Winters axle, I could actually lower the cars overall weight a little in the process.

There have been some excellent handling cars that used conventional rear axles. For decades Porsche has built cars that have their engines hanging out past the rear wheels. Everyone knows this is a bad idea, and plenty of other car manufacturers have proved it. Never-the-less, Porsche made it work very well. McPherson strut suspension, wire wheels, non-rack & pinion steering systems, and pushrod engines are generally viewed as being less than state of the art. But properly executed and applied all of these have outperformed what are assumed to be inherently superior technologies.

My two-cents..........Al English

oldfart

22nd June 2003, 23:42

And a 502 would fit in the engine compartment of the Miata to counter-compensate the crappy rear handling with crappy front handling to make them both superbly balanced! Right!

The Miata from the factory is not the greatest handling machine, but when modified with Racing Beat's (or others) suspension upgrades the Miata IS THE BEST HANDLING CAR through the cones AT THE FASTEST SPEED, EVER, in the whole world.

If your name is Mohammed Ali, you don't need to take boxing lessons!! To assume you could improve Miata's superior handling with a straight rear axle is, I think, pure nonsense, except for narrow requirement applications like straight or roundy racing. Whenever you modify a vehicle you are going against the balanced design of years of accumulated knowledge and extended testing of what works. That is why most custom cars with engine and suspension changes end up being worse than the original. They weren't designed to operate that way. i.e., my desire for equal weight conversion with FULLY retained suspension design. (NO transmission mount)

Normally, a change in the rear would probably require a balanced change in the front. Cause and effect. The Miata is extremely well balanced in it's suspension design with the aftermarket upgrades. It's one of those "made in heaven" modifications. The front and rear work together to the max and both the front and rear grip to the same high G's, and a lot longer than most any other vehicle. That indicates a perfect road car balance that you will not improve upon with a straight axle. But then, I'm predjudiced. I'm attached to my little Miatas.

Nothing personal, I just really like to expound!
Bob :p

Chris92

23rd June 2003, 00:52

Bob when is your car getting done? I'd like to come see it when it is.. are you really going to replicate the PPF trans mount system?

Chris

oldfart

23rd June 2003, 01:22

. are you really going to replicate the PPF trans mount system?
Chris [/QB][/QUOTE]

Yes. I have my own machine shop in my garage. I bought a chunk of 7075 aluminum 13X10X14 to hog out the one piece surround bracket to attach to the T45 2002 Mustang Cobra trans. and fit up to the Miata torque arm. My fun is working on the car, so I'm in no real big hurry to drive it. Just want a really well executed job on each mod I make. I have one in driving condition and one being changed at all times.

Bob

Al English

23rd June 2003, 01:25

Geze Bob, tell us what you really think.

I don't believe I said anything about improving the cars handling. What I did suggest is that some of the cars shortcomings(no they are not perfect) could be improved without giving up too much in other areas.

You might be interested to know that the number one reason for mounting the engine/trans as it is in the Miata has to do with isolating the relatively high imbalance forces that are inherent to the in-line 4-cyl engine. There is no cosmic, "made in heaven", handling voodoo associated with this arrangement.

Originally posted by oldfart:
To assume you could improve Miata's superior handling with a straight rear axle is, I think, pure nonsense, I don't disagree that, as you pointed out, home made cars are often lacking in one way or another. On the other hand, you know nothing of me, my background, or my capabilities. Maybe it's "nonsense" to assume I don't have a handle on the "balanced design of years of accumulated knowledge and extended testing of what works".

"Nothing personal".........Al English

Skyler

23rd June 2003, 01:28

Originally posted by oldfart:

The Miata from the factory is not the greatest handling machine, but when modified with Racing Beat's (or others) suspension upgrades the Miata IS THE BEST HANDLING CAR through the cones AT THE FASTEST SPEED, EVER, in the whole world.

If your name is Mohammed Ali, you don't need to take boxing lessons!! To assume you could improve Miata's superior handling with a straight rear axle is, I think, pure nonsense, except for narrow requirement applications like straight or roundy racing. So do you think that a solid axle factory powered Mustang would not be capable of taking down a SC Miata at an autoX? I have seen this happen and it is rather embarassing to see.

oldfart

23rd June 2003, 01:53

The function we tried to maintain was the lifting of the engine with the PPF design which has nothing to do with the running of a 4 cylinder. The decision was made at Ford Motor Co. in the 215 Miata prototype, not by me. I sure run into a lot of soft egoes on this site. Must be my approach. You could be Einstein and I'd still make the same comment. The intent is really not to put anyone down, or question one's experience, inteligence, understanding, ability or the like, but to discuss facts as we see them for the benefit of others without our insight. Your abilities may exceed the rest of us, but it's the average guy reading these comments that is going to take it to heart and probably be real damned disappointed in having tried to match a God-like project someone else may be able to accomplish. Next to impossible in one person's mind is a snap to others. Depends on where you've been. Please understand, we may make sharp comments, but they are intended to address the subject not the member. It is very hard to razz someone in print without having an offensive sound. That's not the intent, and I certainly do not have all the answers.

Cheers.
Bob

oldfart

23rd June 2003, 02:01

[/qb][/QUOTE]So do you think that a solid axle factory powered Mustang would not be capable of taking down a SC Miata at an autoX? [/QB][/QUOTE]

Apples and oranges. Not pertainent to the discussion. A motorcycle can take down the Mustang. Sissors cut paper.
Bob

oldfart

23rd June 2003, 08:24

Apples and oranges. Sissors cut paper.
Bob [/QB][/QUOTE]

Put the same driver in both cars and time them through the same course that the Racing Beat Miata holds the record for, and when the solid rear axle Mustang, OR Miata even comes close, I'll eat the probverbial shorts! Solid rear axles in a Miata were a joke at Ford. Always gets a chuckle. Not that it isn't or can't be done, it just gets no respect. Earn the respect and stop the chuckles. Prove it.
Bob

Skyler

24th June 2003, 14:03

Does anyone have a pic of the underside of the car with all the rear suspension removed?

oldfart, you have to realize that when building a drag car, people like to be original. I don't want to build an inferior rear end setup. I want to build the best possible thing that I can come up with so I never have to look back. I don't want a car that handles great. I could care less about that to be completely honest with you. The only time this car will need to turn is the occasional stop light/sign and at the end of the track. I got this car because it is light, RWD, and easy to work on. It is actually a pretty good platform for a cheap drag/street car. I am tired of seeing Mustangs and old hot rods go down the 1320. I want to put on a show for the folks here and then drive home in it!

oldfart

24th June 2003, 16:03

Al English

24th June 2003, 23:52

oldfart

25th June 2003, 05:31

Sissors cut paper.
It's just a reference to the game. Sissors cut paper, stone breaks sissors, paper covers stone, sissors cut paper......etc. It's a circle jerk. There was never a lasting fastest gun in the old west because as soon as you gained the reputation, someone shot you. One can talk in circles without facing facts, but in the end, facts cannot be argued, you simply have to look them up or prove it. If RB's Miata can hold the Motor Trend record through the years against Porsche, Corvette, Mercedes, etc., etc., I think the question of handling has been proven. I don't see a solid rear axle on the list. For specialized applications, which were not being discussed, we all agreed early on that straight was the way to go.

We've beat this one to death with a stick. Have you found any 10" wrinkle slicks less than 26" in diameter? Ever thought of 4 wheel direct hydraulic drive.... no driveline losses? Helium in the tires? Nitroglycrin in the gas? Drag tires made out of old Viking "sticky" football catching gloves? (ha) Gyro stearing correction for the strip? Extractor turbo tuning for Miata? Other interesting subjects for a straightline Miata?

rsa

25th June 2003, 10:57

oldfart

25th June 2003, 13:37

Crash41301

25th April 2005, 10:27

Was bored and stumbled upon this old thread while searching for something else.

Just as a datapoint: My stock IRS'ed miata also does VERY consistant 1.6X 60fts, and at the last event with my new found power from the built 1.8L, I pulled a couple of 1.5X 60fts. I think with more practice, 1.5X will be consistant as well.

What toll will this take on the rear suspension? I dunno. I've fabricated some bracing back there that is similiar to the stock 94 rear bracing, only thicker tubing, and the front ties into the plates for my welded in cage. I also have the big plate for the TII rear end back there bracing the front of it better than probably any other brace. My only worries are twisting the stock control arms, as well as the frame of the car. I've got a welded in 6pt for the frame with intentions of a full 12pt to keep the car from twisting itself into a junkyard. The control arms, I guess I'm going to be waiting to see what these do over time...

As for wrinkle wall slicks, I'm running 24.5/9.5/13's on 13X8 wheels. They are a tad too wide, but the hieght it fine.

Thats it, carry on good people :cool:

me

4th May 2005, 19:55

Crash

Strange but I was looking for something and ran across this thread. I have Skylers old car and I am building a rear end based on the Cobra 8.8 center section. I don't have Skylers old setup, that went in Cam's car so I get to start fresh. Not really building the car for 1/4 mile but I'll have to try it at least once........

Looks like your car will soon be the one to beat.

Larry

GodPossessed

5th May 2005, 10:47

Originally posted by me:
Crash

Strange but I was looking for something and ran across this thread. I have Skylers old car and I am building a rear end based on the Cobra 8.8 center section. I don't have Skylers old setup, that went in Cam's car so I get to start fresh. Not really building the car for 1/4 mile but I'll have to try it at least once........

Looks like your car will soon be the one to beat.

Larry Larry - Are you going to get the parts from Diamond Motorsports that relocate the rear shock mount a bit. I heard that will allow you to run the bigger CVs.

Mark

Crash41301

5th May 2005, 11:56

Originally posted by me:
Looks like your car will soon be the one to beat.
Especially since I just bought an NX direct port setup to go on top of the already 98mph 1/8 car 1.4 60ft's here I come :)

Either I'm lifting the wheels on this car or I'm breaking the TII diff... :D

Steveamnmn

6th May 2005, 23:12

Originally posted by wsl:
It really falls down at higher RPMs, like there is nothing left in the top end. I'm assuming the engine is not showing any obvious misfire. So, if the plugs show lean after a hard pull, suspect your fuel supply system. If the mixture looks okay, suspect your valve springs. Under hard use with an aggressive ramp cam, valve springs can "go away" rather quickly.

Steve A.

me

7th May 2005, 07:41

Originally posted by GodPossessed:
Originally posted by me:
Crash

Larry Larry - Are you going to get the parts from Diamond Motorsports that relocate the rear shock mount a bit. I heard that will allow you to run the bigger CVs.

Mark Mark, do you have a link for them? Thanks, Larry

MV8,Mstr ASE/A&P/FCC

7th May 2005, 09:59

Looking at the rear control arms you will notice that the entire lower shock mount is a one piece cup, sitting in a pocket and only welded around the top. If your running standard 2.5"i.d. coilovers, the lwr mnt can be moved inboard atleast an inch without the spring contacting the swaybar endlink or upper control arm. A new hole for lwr shock bolt installation is required. Moving the shock like this will increase the spring rate, reduce shock travel, and dampening, all to a small degree. I'll be moving mine once I get my hubs because it's easy to do for extra clearance. I'll be using the 90-95 taurus outer boots also. Might as well, since I need new grease and clamps. They obviously won't fit the big cv's.

Considering that the tbird weighs around 5000lbs full of stuff and people and has a reasonable amount of power, I think the bigger cv's are overkill.

Mark Williams finished broaching my miata hubs. I should get them back this week. Cost is $50 for machine setup then $15 per hub. It's best to send a ford hub with it. Since they have already done mine, it may not be necessary.

Martin may do it if you can get in touch with him. In hindsite, I didn't try that hard.

I have read the 99+ cobra hubs are also 28 spline, just a bigger bolt pattern.

Centering the diff case in the subframe offsets the pinion and mounts to the passenger side, which puts the 3"o.d. driveshaft in the optimum position to clear the fuel tank and parking brake. It also will result in equal length shafts.

GodPossessed

7th May 2005, 16:20

Originally posted by me:
Originally posted by GodPossessed:
Originally posted by me:
Crash

Larry Larry - Are you going to get the parts from Diamond Motorsports that relocate the rear shock mount a bit. I heard that will allow you to run the bigger CVs.

Mark Mark, do you have a link for them? Thanks, Larry http://www.ls1miata.com/

I spoke to Martin at length about his experience with axle/CV failure on the various 7.5" installs that he knew about. He said that the only breakage comes with super aggressive drag starts with sticky tires. He has seen a few monsters break stuff in the hands of an over zealous journalist trying for big 1/4 mile numbers.

Mark

me

7th May 2005, 16:59

Originally posted by GodPossessed:
I spoke to Martin at length about his experience with axle/CV failure on the various 7.5" installs that he knew about. He said that the only breakage comes with super aggressive drag starts with sticky tires. Mark [/QB]Thanks Mark. I am going to do super aggressive starts with sticky tires, thats why I opted for the 8.8. I talked to Martin the other day and he thought the 7.5 was fine but I am into overkill and not having to worry. I have some 99 Cobra half shafts coming. Cornering is secondary on this car so if I have to move the spring/shocks a little bit it is no big deal.

Larry

R. Littlewood

7th May 2005, 22:16

On my website under "suspension" you will see how I moved my shock rearward, as well as an example of what Alberta road salt does to a swing arm.

Rick.

me

8th May 2005, 07:26

Thanks Rick, very good pic's. I live in Michigan so I am familiar with salt. The car I am working on is from NM. so I have a good fresh start. This car is a race only car and I have been contemplating mounting the rear diff solid, or very close to it with thin poly washers. Thoughts on that?

Larry

me

8th May 2005, 07:27

Thanks Rick, very good pic's. I live in Michigan so I am familiar with salt. The car I am working on is from NM. so I have a good fresh start. This car is a race only car and I have been contemplating mounting the rear diff solid, or very close to it with thin poly washers. Thoughts on that?

Larry

R. Littlewood

8th May 2005, 17:21

What is wrong with using the Ford rubbers to hang the diff? They come free with the diff and are unlikely to fail you. They are a cinch to mount to the Miata K. They also provide some shock absorbing for your drive line. Since I don't know much about racing, you may have excellent reasons to firm things up a bit. If so, I don't like to mount anything completely solid. I leave room for a bit of thermal growth or to absorb vibrations. Your thin washers may be the answer. Remember that you will add or remove those shims to adjust your drive line angles so build it with that in mind.

Rick.

me

8th May 2005, 21:39

Steve, Thanks for the input. I was just kind of thinking over what you wrote, letting it soak in a little. Part of my concern is that if the front wheels come up at the start unequal length halfs would contribute to drift. Probably never happen but just something I was thinking about. I tend to make things more complicated than they need to be.

larry

JohnB./CRUZ-MSL

8th May 2005, 21:55

me

8th May 2005, 21:59

Originally posted by R. Littlewood:
What is wrong with using the Ford rubbers to hang the diff? They come free with the diff and are unlikely to fail you. They are a cinch to mount to the Miata K. They also provide some shock absorbing for your drive line. Since I don't know much about racing, you may have excellent reasons to firm things up a bit. If so, I don't like to mount anything completely solid. I leave room for a bit of thermal growth or to absorb vibrations. Your thin washers may be the answer. Remember that you will add or remove those shims to adjust your drive line angles so build it with that in mind.

Rick. I've been watching the Mustang forums and the one reason Cobra guys are switching is wheel hop. Not to say that bushings are their only problem but it is a source of windup which contributes to the start of wheelhop. This is never going to see the street so I have no noise/vibration concerns.

GodPossessed

9th May 2005, 10:48

I am not an experienced drag racer, but the guy who built my motor is. He has mentioned that equal tire pressure has made the difference in getting a nice straight start on his cars. He uses a tube that attaches to both rear tire valve stems and equalizes the pressure.

Mark

Al Cooper

9th May 2005, 11:13

Originally posted by Al English:
Early in this thread there was talk this would wreck the car's handling. That is not a given. Al English 1990 Racing Beat Miata
This Miata was our first Miata project vehicle. Recongized world-wide by its destinctive paint scheme and body work, this Miata was used to set MotorTrend Magazine's all-time slalom record.

(Update) Rocketing to a new 600-foot-slalom record for a certified production car, the (2005) Elise made us wonder if we'd inadvertently set up a 500-foot course instead. Nope: While the Boxster S is no slug with its 70.9 mph best, the Elise's furious 73.2 mph is peerless. While both mid-engine cars exhibit uncanny balance, the Lotus's non-power-assisted mechanical steering offers the kind of feedback and immediacy normally found in race cars. The next closest rival through the cones is a near-track-ready $193,000 Ferrari Challenge Stradale (also mid-engine) with its 72.7-mph slalom speed.

Gee, Al. Guess you should really take that back! Show me a solid axle that even registered in the competition. :p

Bob

Al English

10th May 2005, 19:52

Originally posted by Al Cooper:
Originally posted by Al English:
Early in this thread there was talk this would wreck the car's handling. That is not a given. Al English 1990 Racing Beat Miata
This Miata was our first Miata project vehicle. Recongized world-wide by its destinctive paint scheme and body work, this Miata was used to set MotorTrend Magazine's all-time slalom record.

(Update) Rocketing to a new 600-foot-slalom record for a certified production car, the (2005) Elise made us wonder if we'd inadvertently set up a 500-foot course instead. Nope: While the Boxster S is no slug with its 70.9 mph best, the Elise's furious 73.2 mph is peerless. While both mid-engine cars exhibit uncanny balance, the Lotus's non-power-assisted mechanical steering offers the kind of feedback and immediacy normally found in race cars. The next closest rival through the cones is a near-track-ready $193,000 Ferrari Challenge Stradale (also mid-engine) with its 72.7-mph slalom speed.

Gee, Al. Guess you should really take that back! Show me a solid axle that even registered in the competition. :p

Bob I should have enough sense not to comment, but apparently that's not the case.

- Many things on cars are there because people think they need it. The mediocre IRS found on most cars is there to satisfy that demand.

- With so many people brainwashed into thinking they need IRS, a sports car manufacturer would not be doing themselves any good to offer a solid axle car. Consider the current Mustang; although comments of the cars handling are rare, the car is heavily criticized for having a solid axle. That has everything to do with "coolness factor", and little to do with reality.

- A typical smooth surface slalom course is one of the last places IRS would offer any benefit.

- As I pointed out previously, the various benefits of IRS are not had without some drawbacks.

- The updated tests you quoted are all mid-engine cars. That is not a layout that lends itself to having a solid axle. While a DeDion axle could be used, it doesn't package well. You might find it interesting that the McLaren cars which dominated the 60's Can-Am series had DeDion axles. They were pretty much unbeatable until the Porsche 917 came along. Yes, the 917 did have IRS, but the 1/3+ more horsepower it had contributed infinitely more to it's success than the type of rear suspension it had.

One of the absolute worst reasons for doing something is because everyone else believes that's what you should do. That's what see happening with IRS. Bob, you of all people should understand that. I could write a long list detailing all the reasons one should not put a Rover engine in their Miata. Although every point I made would be true, the fact is the Rover/Miata is a nice combination. IRS is not better in every way, and solid axles do not suck. There is a lot more overlap between the two designs than people either realize, or want to admit.......Al English

c901

10th May 2005, 20:17

Anybody remember off the top of their head what the Racing Beat Miata's speed was in the slalom?

Cory

Al Cooper

11th May 2005, 01:57

Originally posted by c901:
Racing Beat Miata's speed? Cory 63??

Bob

Al Cooper

11th May 2005, 02:55

Originally posted by Al English:
I should have enough sense...Al English I'll give you credit for your ability to learn. It's just awful slow in coming and you should KNOW by now that it does no good to argue about facts.

The cornering effects of a solid axle and an IRS system are totally different. The wheel angle to the pavement, tire deformation under load and subsequent traction gained by the IRS design were the principle reason for the institution of independent A frame tubular rear suspension in race cars. I don't think that the Volkswagen or Porsche have ever been accused of poor handling, nor have they NEVER had solid axles. The Corvette dropped the solid rear axle due to improved performance in side g-load tests, not customer mis-information led demands.

For load carrying trucks, drag racing cars and perhaps a golf cart you are correct. Henry Ford wasn't looking for a CART racing vehicle. He wanted CHEAP and FAST. Lucky if you could even keep your seat in a tin fliver for the lousey suspension. Modern day straight axles are nothing but band-aide mutants of Henry's old ring and pinion straight axle suspension.

The designers of the Miata were some of the best engineers the U.S. had to offer, particlarly the suspension engineer. (And you too, John) The results speak for themselves. We were given a $15,000 underpowered car that handles like a $50,000 race car. If you think you can take a fully designed Miata and improve the handling with a re-design modification to include a solid axle arrangement, you, Sir, need to commit yourself and throw away the key. It was not designed for one and could never perform as well with one, given the same handling requirements. Now, put a little more power in the car without disturbing the very careful and sensitive design balance.... And the Rover is one solution that does that perfectly.

For total maximum acceleration in a straight line or hauling rocks, you should really find another vehicle to modify, like perhaps a Ford Mustang or a Mack truck.

Lord love a duck, man! Are you serious? (LOL)

Bob

me

11th May 2005, 06:32

I see about 42 cars run every weekend that seem to handle pretty well with straight axles, even when on road courses. Dig up and compare Nascar lap times on road courses with other cars running the course and it is suprising how fast they are.

Larry

MX-5.0

11th May 2005, 11:01

Al Cooper

11th May 2005, 12:06

Originally posted by me:
I see about 42 cars run every weekend ...and it is suprising how fast they are. Larry You miss the point. Big engines make cars go fast in the straightaways, but they do not improve cornering. Straight axles are REQUIRED BY REGULATION in those cars to keep the field evenly comparable, not because they corner better.

Those cars were not designed to run on a concourse, but they have been modified to do the best they can. The only reason they do well is because they have big brakes to slam on at the corners so they can make it around without sliding out. Watch them poke around the corners on their tippy toes. Then watch a CART car smoke up a corner. NO COMPARISON!!

Equally balanced weight on all four wheels, ultra light unsprung weight with soft fat tires, IRS suspension, low CG, firm ride, (anti-sway bars, stiff suspension) and comparable power would leave those clowns so far in the dust you would not believe it. They banned four wheel drive for the same reason.

It's good to form an opinion, but you should study this subject more before making your conclusions as it is really an interesting and challanging engineering subject. One short book and you will be of a different opinion. If our Miatae would have performed better with a straight axle, don't you think they would have saved a bunch of money and built it with one? Get serious guys!! There was a purpose to everything you're looking at.

Bob

Al Cooper

11th May 2005, 12:37

Originally posted by MX-5.0:
[QUOTE] Most consumers don't know an IRS from the IRS. Bravo! Here is a chance to appreciate a real IRS.
Please review the links on this page:

http://www.sylva.co.uk/index.shtml

It's the same concept the Miata was based on, only home-made. I could list a couple dozen other better references, but any car nut will enjoy sifting through these pages!!

Bob

MV8,Mstr ASE/A&P/FCC

11th May 2005, 12:52

Originally posted by Al Cooper:
[QUOTE] Then watch a CART car smoke up a corner. NO COMPARISON!!
Bob It's not the irs, it's the 50lb flywheel ;) .

I don't wish to recieve Bob's wrath but I agree with Al English. Your making large generalizations all over the board Bob. Do you want to discuss street cars, drag racing, or road racing? Are you saying all irs cars are better than all solid axle cars in every aspect? Please be specific.

Al Cooper

11th May 2005, 13:49

Originally posted by miatav8, Steve J Are you saying all IRS cars are better than all solid axle cars in every aspect? Please be specific. [/QB]Gee, I thought that was more than clear and ultra specific. I am addressing handling in the corners, i.e., slolam course, road course, the primary advantages of an IRS over a straight axle in a modified Miata for that application.

Granted, there are advantages for the straight axle over IRS as I stated. All suspensions are still just a compromise. I think most readers of this conversion forum will agree that our typical common goal is go-fast with superb over-all handling. I also believe that the majority of readers prefer the all-out ability to go around the corners to all-out straight line acceleration. There has to be a choice, you can not have it both ways, but you CAN have a compromise that KINDA does both.

Both are fun and exilerating and I've been both places. I'm saying that for the go-fast straight line car, or dump trucks the straight axle is the hands-down suspension of choice. I've seen some impressive IRS conversions for trucks too, but the application is not haulin' rocks; It's not all black and white. The straight axle is not the axle of choice for the Miata if you want to race around corners.

Wasn't that clear?

Bob

Al Cooper

11th May 2005, 13:57

Originally posted by miatav8, Steve J
It's not the irs, it's the 50lb flywheel ;) [/QB]Are they really that heavy? Well, I guess if that works, but it sounds awfully heavy to me. The CART cars don't look heavy enough to push that big a flywheel. I thought they didn't have one at all! i.e., the manual starter motors and the high RPM's.

Bob :rolleyes:

MV8,Mstr ASE/A&P/FCC

11th May 2005, 19:34

me

11th May 2005, 21:24

Ya, it was crystal clear to me too, but I don't know if it was the conclusion that you were after.

Larry

Al Cooper

11th May 2005, 22:01

Originally posted by me:
... I don't know if it was the conclusion that you were after. Larry Read what was written, slowly, twice. Spell the words to a friend if necessary. It is all consistant. No double talk, no argument for the sake of argument. Just good acurate supported information rather than, ah, 'suggestive inuendo'.....

Bob :confused:

Al English

12th May 2005, 20:14

Originally posted by Al Cooper:
Originally posted by Al English:
I should have enough sense not to comment...Al English I'll give you credit for your ability to learn. It's just awful slow in coming and you should KNOW by now that it does no good to argue about facts.

Bob That's exactly what I was getting at when I started my post by saying: "I should have enough sense not to comment, but apparently that's not the case." I say that because no amount of examples, evidence, or facts can dissuade some of the participants here from their sometimes mistaken opinions and perceptions. Feel free to post any additional wisdom you may have on the subject, anything I might say has already been stated in one of my previous posts.........Al English

Al Cooper

13th May 2005, 12:49

Originally posted by Al English:
no amount of examples, evidence, or facts ... in one of my previous posts.........Al English [/QB]Al:
I have a normally agressive way of speaking which I continually apologize to you for. We've been there too many times to go there again. Accept it.

I'm looking for examples, evidence and facts in any of your previous posts, but all I see is opinion, Al. Before I began to participate in this forum, I was warned that you would become a consistant antagonist. Your reputation preceeded you. That's fine. I'm LOOKING for facts for people like you, not just contrarian mumbo-jumbo. I respect your knowledge, intelligence and your right to opinions, (everyone has one and is intitled), but I'm looking for comments that contain convincing information, not vague unsupported and generalized hypothesis.

Please tell me why/how a solid axle would be an axle of choice for one of our Miatae to improve the handling, particularly in cornering. That was the discussion you entered into with your comment. I REALLY want to hear some related FACTS. Be specific. Please document your position so we can study and evaluate the information, since if it can actually be supported, it would interest an awful lot of Miata conversion owners. I can find no posts to support your position. I can find no references that would even hint at such a proposition, but many that opose the suggestion. Please present one. Reference a web page, maybe??

Sample example: Adding the weight of a straight axle to the rear of a Miata V8 conversion will better balance the vehicle weight distribution and increase the ability to grip equally on all four wheels in a hard corner. In addition to improved straight axle launch, understeer in the corners is reduced and overall handling is improved.
Reference web page XXX. Improved track time was XXX seconds.

Of course, this is fictitious and I'd obviously have some questions, but this is the kind of input that becomes constructive. Thanks no end.

Bob

Al English

14th May 2005, 08:08

Hi Bob,

If you review all my posts in this thread, and those made on the same subject in other threads on this forum, I have never suggested a straight axle would improve a Miata's handling. When this same misunderstanding took place earlier in this thread I responded to you:
"I don't believe I said anything about improving the cars handling. What I did suggest is that some of the cars shortcomings(no they are not perfect) could be improved without giving up too much in other areas."

While I disagree with some of the statements and examples you have posted, the contradictions between my posted remarks and what you have said are not as great as you seem to think. If you re-read what I have actually said you might agree. Perhaps you should, as you suggested a few posts above to "me", "Read what was written, slowly, twice. Spell the words to a friend if necessary. It is all consistant. No double talk, no argument for the sake of argument. Just good acurate supported information rather than, ah, 'suggestive inuendo'". The real point of contention is that I believe the trade-offs between the two designs are much less than you do.......That's it.

I said I wasn't going to comment further, but I thought one last post might clear this up. Like most here, I visit this forum to help people when I can, and hopefully learn something myself. While some may be entertained by the the occasional argument, that's not why people come here. I really don't have anything more to add to what I previously posted on the topic, and I'm most definitely not going to change your mind about anything. That being the case, the only reason to keep this going would be for the sake of argument. I don't want that; the other participants here don't want that; and while the the hosts of this forum have been polite enough to let this continue, I believe they want don't that either........Al English

Gene-M

14th May 2005, 13:48

R. Littlewood

15th May 2005, 01:42

Al Cooper

15th May 2005, 14:31

Originally posted by R. Littlewood:
...I spent as much time getting the rear end right as I did getting the engine right! I have a fellow who called a couple days ago who has three RX-7 convertibles. He asked about what we Miata guys did for rear ends. He is going to install an LS6. After a short discussion of what some of you have done, he deceided to go with a Corvette transaxle IRS. His only objective is raceability.

I have to agree with his decision. Depends on your ambition, goals and how much you know about race cars, I guess.

What would you guess the actual time to complete would be? Costs?

Narrowed straight axle kit.......two days?
$1300?
Custom rear transmission mount and '95 up Torsen.................................half day?
$200?
Lincoln IRS...........................two weeks?
$2500?
Corvette transaxle.................two weeks? Three?
$4500?

How long did it take you? How much?

Bob

MV8,Mstr ASE/A&P/FCC

15th May 2005, 17:01

I had the benefit of following Rick's installation. Total time would be 3 or 4 8 hour days.
3.27 7.5 complete subframe and drivshaft=$100
New axles=$300
Hubs broached=$115(including shipping)
Steel used=$20
Driveshaft made to my specs with new joints, a new weld yoke, painted, and balanced=$150
New nuts and driveshaft bolts=$12
taurus boots and inner tbird boots with grease and clamps=$45

That's $742.

Al Cooper

15th May 2005, 19:05

MV8,Mstr ASE/A&P/FCC

16th May 2005, 09:52

I bought the whole assemble to consider the option and to see exactly how it is mounted and reinforced. The ford tbird irs 89-97 is extremely heavy, with massive cast iron lower control arms, stamped upper arms, and drum brakes. The newer bird has a much more refined rear sub (see LS1's 2003 example). Also, to use the whole thing would have been as much trouble as a solid and with no changes to the front track, would have looked very hillbilly/red neckish, as well as adding severe understeer.

With parallel lower control arms, the problems with toe control under power would be the same as the miata except the pivots are further apart and the bird has two, small 4" links that almost solidly tie the forward edge of the lower control arms to the subframe pivot bolt through extremely thin, hard bushings. This doesn't increase nvh because it only effects toe control and is decoupled in vertical movement.

The newer suspension uses alloy control arms which also act as trailing arms for improved toe control without add-on devices since they are not parallel to each other. I haven't seen one up close to know any other details.

R. Littlewood

17th May 2005, 00:21

Here are the costs I incurred to mount the Cougar differential:

Task………..………………labor………Parts
Buy the pumpkin…………..4 hours….…$250
Weld in the pumpkin………8 hours…….$0
Measure axle length………..4 hours….…$0
Spectro. Analysis…………..2 hours….…$50
Weld axles………………....4 hours….…$25
Boots and repack…………..6 hours….....$50
Machine hubs………………6 hours…….$0
Move shock pockets………..6 hours….…$0
New springs……………..….4 hours….…$50
Disc centering ring………....4 hours….…$0
Bracing and Bob bars………8 hours….…$30
Totals……………………….56 hours……$455.00

From Bob’s numbers I see that this was not that expensive when compared to the other options. What I dislike about this option is that it requires a lot of labor, and some very specialized skills. Metallurgy and welding of the axles, careful measurement of the shaft lengths, machining of the hubs, moving the studs.

Now that mine is in it has some shortcomings. At full extend of the shocks my cv joints bind slightly because I erred on axle length. (Similar errors by others have probably caused some of the shaft failures we have seen) The dirt seals on the hubs were done by me on the lathe and I have doubts about them. My old stud holes are welded shut and my confidence in them is low.

I have a lot more faith in the engineers who built these cars than I do in myself. If you could find a solid (or IRS) rear end with an acceptable width and useable wheel studs you would not have to cut it up. Simply hang it under the car. There will be a lot of brackets and tabs to build and weld in, but these are easy to do and quite forgiving.

Handling is an un-known that will only be answered when somebody builds one, but I believe it would be less work and provide a higher level of reliability.

Rick.

Al Cooper

17th May 2005, 12:44

MX5.7

1st October 2005, 20:01

Crash41301

4th October 2005, 12:15

Nope, he ended up parting the car out.

Me and a buddy who has done many a tubbing on cars did look at my blue miata before I parted it out. Its very possible to do, and not really all that hard either.

MX5.7

4th October 2005, 21:28