the fixed length half shaft IRS versions appear to be based on the old Jaguar XJ6 type rear ends that were quite poor in terms of geometry. A live rear axle is "theoretically" very poor, but many people get them to work well.
I'm driving an old E38 bmw at the moment and the rear suspension of those is a slightly better compromise in terms of geometry than the Jaguar derived units is and it all comes on a cradle. I've no idea about the GTo stuff as we don't get them in the UK.
JAG IRS, design is older than the 1st gen camaro stuff, but the v12 diff is very strong
"The Jaguar IRS is really a fine design, but has a flaw called "dreaded roll oversteer", caused by the action of the two trailing arms when the rear suspension compresses. As you are aware, the cage is mounted to the "frame" using molded rubber mounts, to allow the whole unit to move. It really moves about + or - 3/4 " if you snap out the clutch ! If you really watch this happen, you'll flip out! In a hard turn, the wheel on the side of the car whose suspension's being compressed, is forced rearward by the effective lengthening of that side's trailing arm, while the reverse is happening on the opposite side, pulling that wheel forward ! This, in effect, is rear wheel steering, without asking for it. "
I got the donor car in yesterday - It has an aftermarket intake, Corsa Exhaust, and some dynaspeed and hypertech stickers on the intake. Sound great - about 60,000 miles on it. I'm going to try to use as much of the G8 stuff as I can. I've got to check and see if it has some of the dynaspeed and hypertech stuff in it
I plan on starting on it in a about 2 weeks. I have to finish up a Bronco I'm building for a customer first.
Thanks for the Bronco compliment - I build Early Broncos(1966-1977) in my spare time. I have some better pics, but they were to large to upload.
IRS isn't that big of a mystery. I would use a 9" section and couplers/axles from Dutchman and use C5/C6 uprights and build your own control arms. Actually, I would probably build my own uprights too, but much easier to use Corvette parts. Not that big of a deal although kind of expensive.
The only mystery to me is you might get all the handling geometry right (in the computer obviously) but still end up with wheel hop or harmonic issues due to bushing compliance, resonance, etc. The OEM's can test and model that stuff out, but the home hobbyist might run into some gotchas.
ONe of my bigger regrets with the last car I built was that I didn't go IRS, but probably for the best. It was gonna add $4k to the cost of the car and at the time I was trying to be prudent.
thanks everybody, great advice. I think I am going to do the rear end closer to the end of the project. Still not sure about what I'm going to do - I need to figure wheel size, gear ratio, what back spacing I really want, etc.
What gear ratio are most LS cars running. I have the 6L80 automatic trans and I currently have a 373 posi under the car. The IRS on the G8 is suppose to be a 292.
Last edited by blazincopper; 05-25-2012 at 08:33 PM.
I have been looking into IRS for a while now and one of the coolest (definitely not the cheapest @ $8000) ways to do it is with the Heidts bolt-in IRS.
There's a hell of a lot less hassle involved and it just looks bitchin'. Watch the video they have on it in a Camaro running an autocross coarse. Here's the link:
Now if you want to go ALL out, and make your car absolutely badass, put this setup in front:
For those not in the know, this in an Art Morrison AME GT Sport front clip for a 67-69 Camaro, utilizing modified C6 spindles and stock C6 uppper/lower A-arms. I hope to put BOTH the Heidts IRS and this front clip into my 67 Camaro......some day!
It would be easier to just buy the new Roadster shop IRS chassis. Those are so bad ass!
Even though the op already has his donor car, I'll leave the info for others thinking of doing similar.
We offer the IRS setup in two flavours: Full chassis or separately
Our setup is based around specific geometry setup for pro-touring sized vehicles and their appropriate track widths so you don't have to run rear wheels with weird offsets or any external flares, bulges etc. It has been engineered from scratch around the weights, sizes and intended use of our pro-touring/performance vehicles and as such it is not based on an antiquated Jag setup or modified street rod platform. The Fast Track IRS also uses conventionally mounted outboard brakes for easy rotor and pad changes and countless brake package options. It is also built to accommodate high horsepower (+600) with drive axle options to withstand hp well into the 4 digit range.
Here is the IRS as a full chassis for a 1st Gen Camaro:
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
Linear Mode
