MAVRIC83

i'm thinking about putting corvette independent front and rear suspension on my 83' firebird. i was wandering if anyone has ever done such a conversion? if anyone has could they please post pics of it installed?

Kandied91z

iTrader: (7)

i remember seeing something about it on here. usually people try to convert away from the independent. dare to be different right!

good luck.

bottledbird68

Prepare to chop the hell out of the rearend of the car. Basically say goodbye to everything behind the front seats. I have the swap sitting about half done in my yard cause I haven't had the time to finish it...

FSTFBDY

iTrader: (33)

Care to take some pictires? id like to see why You say you have to ditch the back seats..

pic's I saved because if I dont go ford 9inch Im gona go IRS in my vert.

http://s89724942.onlinehome.us/image...IRS%20rearend/

bottledbird68

The stock trailing arms on the IRS wind up taking the place of where the seatbelts used to mount. You might still be able to squeeze the seats in but it would be really tight, or, you could have some of the seat frame removed and recover them. I just completely did away with mine because I decided to tie everything into the cage. I intended for the car to see autocross use. Lately, due to a lack of time and ambition, it's turned into more of a storage shed... Let me see when the next time I'm home in daylight is and I'll see what I can snap for you.

gearhead0384

iTrader: (7)

IRS sucks, the little improvement is not worth the hastle. Also IRS is crap for Drag Racing (what F bodys are best used for).

Kevin

TexasLT1

Do you're own research instead of beating the horse...

gearhead0384

iTrader: (7)

I did my own research and I am expressing my opinion which I am entitled to do.

Kevin

TexasLT1

Then please enlighten us as to why IRS sucks. Funny that the Corvette has used it for something like 40 years, and guys have gotten 1.5 60's out of it at the track. You're right, thats crap for drag racing.

german-motorsport

MAVRIC83 welcome to third gen!

The Q you have reminds me of the first 3rd gen project car in 1985 a 4zyl Iron Duke with a 4 speed manual trans!
I asked some friends if i could swap in a V8 and a 400Th and they all burst out with a big laugh!

We do have a strange 3rd gen policy sometimes on this board:

1. swich ya brain off and answer to a Q!
2. dont answer to the Q and post technical spam!
3. post a private opinion that does not answer the Q !

With pro Touring coming up some time ago people jumped on the topic on brakes and suspension upgrades alot!
While you get familiar in here try to make a search on: "Corvette rear" or "indepentend IRS" the topic was up several times!
There is even a company in Florida offering a Vette rear install!
There is a 3rd gen member whos brother has a website with lots of pics!They are helpfull and yes they even answer mails!

Check for the 1gen mega swap called the "Mule" read the story about this "vette" frontsuspension and you´ll notice that the guy is a GM ingineer with lots of technical background he had to develope lots of parts for the 1gen to make it work.
You´ll will end up with a full front cradle of own design to get it running and the cots of such a project are one thing but be ready to do lots of brain nights!

The rear vette axle is when you see the pics a project for people with a shop or a club thing or you call companies like FAB but again lots of money if you cannot:weld,dont have a big garage,cant wrench or need help when changing tires!

What happens when you put a vette rear in a 3rd gen ?
Youll love it!Driving a IRS is a thing GM din´t wanna spend
for 3rd gen cause this would change the sticker price so much upwards!
GM DID BUILD A BLUE PROTOTYP! ONLY ONE !

Originally posted by gearhead0384
IRS sucks, the little improvement is not worth the hastle. Also IRS is crap for Drag Racing (what F bodys are best used for).

I am sorry that a member of this board is posting such technical trash!

The IROC race was a touring kind race series, if you read Books about the 3rd gen history you´ll notice that GM had high goals
with a list of competitors that named porsche and others!
The handling issue was a big one when they produced the 3rd gen!

Originally posted by gearhead0384
IRS sucks, the little improvement is not worth the hastle. Also IRS is crap for Drag Racing (what F bodys are best used for).

In a old threat about IRS installs in a 3rd gen we had comments like this before.........and i always thought the internet would make people smarter!


Drag racing a big topic for the GM Company in 80/81 when GM rolled the prototypes? PLSSS take a look at those GM Model years!hahahahahahah!

I would say the way you asked that a rear IRS is a project you might thing about ...but heay as a old guy i would love to see someone moving the 3rd gens into the future with a vette C5 frontsuspension!

Check our postings and you´ll find the IRS threat!

german-motorsport

the vette rear pic from Florida

german-motorsport

1gen with vette susp...lot of work eveso a bit easier due to the 1gen front susp design

gearhead0384

iTrader: (7)

I guess my opinion on what Camaros and Firebirds are generally used for is different that yours. If you take a look though on the board most people like myself are in to strait line performance. I don’t know what your guys intentions are for your car. But I just gave my opinion on what I think about IRS. I am not really all that off basis though. I know guys with Cobras who convert there IRS to a solid rear. A friend of mine sold his 2001 Cobra because he did not like the IRS and bought an LS1 Trans Am. He could not stand the wheel hop, so he got rid of it. And honestly an IRS Camaro would be a cool project, and a cool car to have. I guess it just different opinions on how we intend to use our cars.
Kevin

TexasLT1

Yes, and the Ford IRS DOES blow, Corvette does not. Simple as that. You're entitled to you're own opinion, I'll give you that much, I just think you've got bad information. And I will give you that a lot of this board has their cars set-up for drag racing only, but a lot of this board also does autox and road racing, where the IRS would be key.

biohzrd

i am in the process of doing the irs swap right now. for those who think it sucks....... well thats your opinion. i guess porsche, ferrari, and lamborghini all have it wrong too.
anyway not to beat a dead horse about this, irs does have its big advantages. i too have a friend with a 2003 cobra. had many of the same problems that others have with it. we on the other hand did not pull the irs out and shove a solid axle in its place. all we did was convert to an automatic tranny. problems solved. dumping the clutch in any car with 350+ rwhp will break rear end parts. since the swap he hasn't had any breakage in the rear. it hooks its you know what off to the tune of 1.60's in the 60'.
all im trying to say is that you can't blame the design because of driver abuse. an automatic tranny will not shock the irs as bad as a manual.

GTA-SPD

My brother has this done on his Camaro. I wouldn't go through the hassle in the front, go with a coil-over/tubular a-arm up there. Here is a taste of what is involved. FYI, the rear seats and gas tank remain completely stock, as does the entire Vette suspension. If you want more pics I have them, just send me an e-mail.

Hey, that pic that's from "Florida" is of my brother's car. That's just fine, I just thought i'd set the record straight. That is a Colorado car bubba.

GTA-SPD

#2

GTA-SPD

And that is a stock Camaro tank up in there.

TexasLT1

Where is Frederick, CO at? I would love to come see that car in person some time.

TexasLT1

Where is Frederick, CO at? I would love to come see that car in person some time.

gearhead0384

iTrader: (7)

Ok well I understand that IRS can be made to not have massive wheel hop. But to be honest, porsche, ferrari, and lamborghini are not desingned for drag racing.

Only Reason I am Biased to a solid rear is because all my friend who have IRS and RWD have way too much wheel hop (2001 Cobra, 89 T-Bird Super Coupe, and 88 moded Turbo Supra). My opinion is only based on these facts that I have witnessed first hand.

Also that IRS in the pics Looks really awesome!

Kevin

1320 Right Ln.

That's pretty sweet dude... how long did it take? does the brackets n' stuff come in a kit, or is that all fabricated? looks like a clean install in the pics. Oh yea, n' what year is the camaro and the corvette rear?

TexasLT1

All fabricated. No one makes a kit. If there was one, you'd see this done a lot more often.

3.8TransAM

Looks eerily familiar to the supposed prototype kit the that GM itslef was going to offer for putting the Vette IRS into the Fbody twins. Its been done on quite a few cars. Supposedly, dimensionally it is a nice fit , just ahving to work out the upper mounting points and what to do with the rear spring.

Been dreaming of doing it to and F or G body in the future at some point. All factory parts once its installed is a bonus if you have problems down the line


later
Jeremy

bottledbird68

You're exactly right, dimensionally it's a perfect fit. Track width is within 1/2" total of a stock third gen so the wheels sit the same without spacers

GTA-SPD

Frederick is about 30 miles north of Denver just east of I-25. It's not my car, it's my Brother's car. He tried to sell it on eBay a while back, but I think that 35 large is a bit more than he'll ever see for it. I really don't think that he wants to sell it, but wants it to look that way.
That was the idea when he did it. He wanted it to look like GM did it and he also wanted to be able to use all off the shelf parts if something broke.

The car is an 87 IROC and the IRS is from a 88 or 89 Vette. I'm pretty sure that all of the C4 years will fit and work just like that thoiugh. The only thing that has been cheanged, as far as I know, is the rear spring (it's an 84 Vette HD) and the rear diff (it's a Dana 44). Originally he had a Dana 36 in it, but when he went with the LS1, that blew up. All of the parts are custom fabricated and installed. The only parts that had to be cut out of the car were the mounts for the existing rear suspension. Everything else was left as is. Also, you will have to figure something out for a torque arm since, on the Vette, it mounts on the opposite side of the diff.

biohzrd

that is a nice install. really looks good i'm going a little different route though with mine. i'm using the more traditional coil over spring approach. it's working out nicely right now, so i'll keep my fingers crossed. who knows maybe a kit in the future. i guess we'll have to wait and see.

FSTFBDY

iTrader: (33)

biohzrd,

You taking pictures as you do this? Mind posting some pic's if so.

biohzrd

i'll try and see if i can hunt down a camara. if not i may just go out and buy one. right now it's in the lay out stage of things. hopefully if all goes well i'll be able to basically put it all in as one unit. i'm going to weld it in, but it shouldn't be a problem with bolting it in. we'll see i guess.

GTA-SPD

I don't know how much fabrication work you've don, nor do I intend to imply that you don't fully understand what is involved here but, this is not a real straight forward "weld-it-up" in your garage kind of project. If you don't have a frame rack (or similar device) to hold the car in perfect alignment whilst you are installing the mounts, you will never get the car to go down the road straight. I can tell you this, it cost around $5000 for the install of the rear in my brother's car. I'm not saying that it should cost that much, but he did it back about 8-10 years ago, and the shop he had helping him (actually he was helping the shop) had never done it before. It is of paramount importance to understand how involved this job is before you start cutting out the mounts for the 3rd Gen rear. Once you make those cuts, it's virtually impossible to go back. Good luck with your project and I hope it goes smoothly. I can say this, what ever you have to do to make it work, it is way worth it.

biohzrd

i know what you're talking about. it is difficult, but i've done things like this before. our shop specializes in custom work. everything from all out race cars to bagged and slammed trucks. we've put irs in a few other cars that didn't come with them. 55' chevy, 92 chevy 1500 with air bags. .... anyway this hasn't been an over night project, but at the same time it isn't the hardest i've done either.

GTA-SPD

I figured as much. I was really trying to make sure that people didn't think this was a weekend project that they could do in thier driveway. Even if there was a "kit" out there, it would still be an incredible undertaking to install right. I'd love to see some pics of the coil-over approach to the corvette IRS when you get it hung in there.

biohzrd

i totally agree with you. this rear setup has a few more challenges the the others i've done, and we're figuring them out as we go along. the coil over is something that is giving us some problems right now. trying figure out how get them set in the correct position on the lower control arms for safty and strength. it's looking like its going to be a long arm/ short arm set up, with adjustable end links. this should aid in getting the rear alignment right.
its is going to have to be somewhat removable b/c right now i'm using an old basket case 89' we had sitting around to do the mock up on first. once i'm satisfied with the results i'll transfer it over to my project car, and weld it in place.

mongse_1

Noticed this thread while doing some searching this afternoon, so I'm bringing this one back from the dead. It can be done and it's not quite as tough as you'd expect.

http://www.quarter-mile.net/images/IROC/IRS/IRS50.jpg
http://www.quarter-mile.net/images/IROC/IRS/IRS51.jpg

The car is used for road racing, so lateral performance was the main concern. That's what the single turbo BB car is for.

Not bad weekend project for a couple guys in a little shed.

MurcoRS

Links wouldn't work...

90formula5spd

uuuhhhhgggg, i have been contemplating the IRS or a ford 9" for the past 3 months in my chassis fabrication class.... still cant decide, but do u guys have ne clue as to whether or not shops would b willing to let me rent out a frame bench? I would REALLY like IRS but the 9" and what not will suffice if i cannot get ahold of a frame bench some how, or how much do you think it would cost for a quality shop to do the work? now i kno you guys dont have exact prices but possible guesses? is the 3rd gen vette suspension setup even possible?

sorry to bring back an old subject

FerrMaro

I decided to resurrect this thread because I couldn't get over how perfectly the Corvette's dimensions match the F-body. And I must commend GTA-SPD for sharing this with us. I can't help but think that this should be one of the only considerations for anyone trying to perform an IRS swap. And as far as difficultly is concerned...well, I just dont think it would be that hard to weld a couple brackets and fab up a torque arm mount...As long as everything's straight and your measurements are correct! Hope you guys are as happy as I am with this option. Woot factory parts!

racing geek

iTrader: (5)

Does that mean you have completed the swap? If so, pictures would be great.

VAN454

This would be very nice, but it would also be a big job.

Jim85IROC

iTrader: (2)

Since this thread has been brought back from the dead, this may be of interest to some:

http://www.ls1tech.com/forums/showthread.php?t=539526

It highlights the install of a C4 IRS into a 4th gen. Since the mounting points for the 4th gen rear are the same as for the 3rd gen rear, there may be some very useful information there.

For those who are worried about how the c4 IRS hooks, don't. There are some VERY fast C4s still using the stock D44 IRS. I can tell you that my 91 Corvette launches a lot harder than my IROC does. When you start getting into big horsepower I'm sure the limitations of the IRS will become much more obvious, but with more sane horsepower levels, the C4 IRS will do fine.

racing geek

iTrader: (5)

Thanks! From skimming over the first page, it looks like a super clean install and seems to be kinda cheap for the rear end that is. I'll have to read it tomorrow since I don't have work/school.

soultron

iTrader: (2)

That looks way easier than it should be!!!!!

Awesome.

FerrMaro

It's definitely in the future! The more I think about it, the more it becomes such a steal...upgraded handling from the IRS and redline launch reliability from the Dana center. Thanks Mr. Moderator for that link...

ploegi

Read thru the thread. Very interesting, and an exceptionally well done install. I must say that was very nice.

One thing I did notice, however, was that the shop performing the install was F-Body Motorsports? AKA 3rdGenResouce? or, at least, a former employee thereof. Such was the impression I got anyway......

ls six

I have been considering the IRS issue since I bought my T/A and since I'm also a big Mazda fan I have been looking there for options.

2nd gen RX7's are common in the salvage yards and used car lots for cheep and have very good rear suspensions.

See page 13.
http://www.rx7city.com/Manuals/88%20...SUSPENSION.pdf

I'll be taking measurements soon but untill then the major bennifits include stregnth as seen by the many V8 RX7 swaps a huge selection of rear ratios from various OE's.
Mazda has been using the same family of diffs for decades and have provided them to other OE's including Honda (S2000) with verry high ratios to Kia (sportage SUV) with very low ratios and ford and mazda trucks.


Any thoughts? I mean besides mindless import bashing.

FlyDoc

in the Jun 08 issue PG 27 they show a 94TA with a C4 vet IRS it it and they were able to do it with out cutting the floor pans. looks like it went in clean and from the pick it looks good.
I am considering doing it. in my 92 RS.

ls six

I'v seen it done without any cutting at all but corvette parts are rare and expensive. Thats why I,m looking at other options.

I'v thought about the catera/GTO rear but it's no more GM than the mazda rear and some of the european weirdness is a turn off. They also use a different wheel bolt pattern than the mazda/F body.

Pocket

iTrader: (24)

Try a Tbird SC IRS

Stephen

iTrader: (12)

Why? Besides the wrong bolt pattern, meaning a spacing out adapter might be needed, the benefits are.....?????

iansane

iTrader: (1)

Instead of having to measure out all the mounting points for all the links and making sure everything lines up the tbird/cobra IRS both use a "cradle" that only has four mounting bolts IIRC. So, it'd be easier in some peoples eyes to mount in another car. The hubs could easily be redrilled to accept an fbody bolt pattern so spacers/adapters wouldn't NEED to be there.