abeomid

Ok today I decided that this will be my next winter project since this winter I am putting the 13BT in.

But I want to start studying about this and want to know if it's possible to have a better Suspension Geometry with the 3rd IRS setup if it's done right?

Please no comments about how it's really hard to do it and stuff like that. I know that already. I just want to know if it's done right, is it possible to get a better geometry that the solid axle?

TIA,
Omid

zyounker

Well, i would recomment getting a second gen IRS, it is about as strong but more "Avaliable". And if you make a sub-frame to hold the rear end, PLEASE make 2 I think it could be done fairly cheap. And i think there are quite a few that would be interested..

And you can get cromolly axles and a Kazz or strange diff for the FC IRS, and it is cheaper.


-Zach

RotorMotorDriver

iTrader: (1)

I personally think questions like this are funny...Of course if its done right it will work, the question is, can you do it right .

~T.J.

Manntis

There are several who have done this, especially in Japan. 3rd gen IRS conversions (and the front as well, otherwise you'd have 2 different bolt patterns and 2 different brake caliper styles) aren't cheap, though.

IMHO the rear suspension geometry of the 3rd gen, while being much pricier and harder to aquire than the 2nd gen, has better handling characteristics. And either is better than a solid rear axle.

abeomid

Well if I change the rear, I will change the front bolt pattern to the TurboII since the inner bearings are the same. But 2nd gen would be good as well since the GX models have the same bolt pattern as GSL-SE.

I am pretty sure that the 3rd gen suspension is way superior to the 2nd gen. I guess I have to ask from ppl that have raced both 2nd gen and 3rd gens to see what they think. This is solely for racing purposes. Not for show.

Manntis

I've only 'raced' insofar as autocross, but for drag racing I'm not sure the 2nd gen IRS would be any good - it has trailing arm geometry that can cause rear-end squat.

I also prefer street cornering as a measure of handling over autocross. @ least at our local courses there seems to be a turn every 20 feet. It's rare for a person to get out of 2nd gear. Jamming through a right turn at 60 kph and staying in the proper lane is a practical measure of handling, IMHO.

abeomid

Drag Racing, that's an insult to me. I'm not gonna take my baby to drag racing.

error402

abeomid I'm glad you asked this question on here. I've actually toyed with the idea myself and would love to see how it can be done. Keep us posted on any news you come across.

-Error402

Directfreak

iTrader: (2)

If I Remember Correctly... a former friend of this car owner told me that

This car has a complete third gen drivetrain, including the suspension.

Might want to look into it. BTW, he owns a shop dedicated to RX-7's as well.

Their website is: RX-7's.com

Manntis

Nope. Romeo's car still has the 4 bolt GSL-SE rear. It does have a turbo, though...

JEC-31

Y'all are going to love this one...
I know a reclusive fellow who guesstimates that the 1st gen RX-7 is about the same width as the 1st gen Miata, a car which has been a little more mass-produced than the 3rd gen. He had a pretty far-out theory that the Savanna ('79 RX-7 in Japan) was originally designed to have IRS but got budgeted down to the Watts-linkage solid-axle, and that 10 years later they used that prototype IRS when developing the Eunos (Miata).

Anybody got access to an early Miata? Crawl under it with a tape measure and let us know. They're definitely cheaper and more plentiful than the FD.

abeomid

Well I have seen that yellow wide-body 1st gen that has the IRS and I've been told it's an Aussie car

Manntis

Miata IRS and rack & pinion steering in a 1st gen would be a fun and less expensive alternative to the FD -> FB transplant

abeomid

well R&P steering would be kind hard since u would have to change engine location so the steering fits under it.

JEC-31

Yeah, R&P would be a real fun journey into Pure Fabrication land. Might as well tube frame it.

abeomid, are you building for a specific series that'll allow these sort of radical mods?

abeomid

yeah it's called MOD class

Manntis

You could mount the R&P forward of the engine instead of under it, since you're changing the spindles and hubs anyhow.

RoTaRyBoYz

romeo's car is running a $2000 ford mustang 8.8 rear that was built almost buillit proof......they took the 8.8,cut it 1" on each side to make it the same length as the mazda rear (from 59" to 57").....

Manntis

OK. the same 4 bolt pattern

abeomid

Well I have access to some TII front and rear subframes. So I might as well do that this winter and then i wouldn't need to make a driveshaft for the TII tranny.

Man this will take so long

Manntis

...and a mount point for the rear diff. The 2nd gen one has a pair of 'horns' that'll make that relatively easy though

RotorMotorDriver

iTrader: (1)

Or you could buy a 2nd gen and modify the engine in that and do some massive weight reduction and use that car . It would be just as fast if not faster than a 1st gen . Unless your like me and you just want a challenge and something different that no one else has .

~T.J.

abeomid

Plus i don't want a crappy looking interior. God I hate the 2nd gen interior. Plus i want to prove to everybody that said 1st gen can't be competitive in Solo that they are wrong. It will be with either a good driver and/or a $hitload of cash

RotorMotorDriver

iTrader: (1)

I agree 1,000,000% . I hate the 2nd gen interior, but the exterior has quite grown on me. Id have to have one with very custom interior for me to fully enjoy it if I had one .

~T.J.

Re-Speed.com

iTrader: (3)

A side note for you on a few things. I have done some research on this subject for a project I am working on.


1) The second gen diff has a LONG pinion. It is about 7" longer than the first gen. The length of the miata is the same as the first gen. This would make you think that the stock first gen drive shaft would work *but* mazda changed the mounting plate on the diff to match the second gen on later miatas.

2) A miata torsen (SP?) style diff can be had easy. Thought to be superior than the clutch style.

3) The ring and pinion on a miata is the same as the first gen. If you happen to have some laying around at least they could still be used. 2nd gen went up in diam. by one inch and then the turbo was one more inch as well.

When I get home I will post a link I have for Miata and Rx7 part interchange. It could help you decide.

-billy