Wanting to know if it is worth my time to try and adapt a '04+ GTO rear suspension to the 'velle? I can get one for dirt cheap (complete), but unless the performance will drastically change, I see no point..

So what do you think? Go for it, or No?

Thanks,
Todd

So I am not at all familiar with the GTO rear suspension, but since you are proposing it I presume it is IRS?

I have converted a couple of cars from live axle over to IRS over the years. The last one was a 2001 Mustang with a converging 4 link like the Chevelle.

IRS can be a mixed bag and people either love it or hate depending on what they want out of the car. If you criteria is 60' times you would probably hate it. It can be very tough to tweak and tune an IRS in a high torque car for good launch hookup and many of them hop like a bunny. Many of the Mustang Cobra guys swap out the IRS for just this reason. It kinda funny though because one of the benefits of IRS is no lifting of the RR tire from torque which would be a good thing otherwise.

But then if you want to go around corners well an IRS can make you very happy. On a Chevelle it will very likely lower the rear roll center and provide much more stable lateral location of the wheels. This stability will greatly reduce the steering corrections required through the turn. The car will seem to groove much better.

IRS can be a mixed bag and people either love it or hate depending on what they want out of the car. If you criteria is 60' times you would probably hate it. It can be very tough to tweak and tune an IRS in a high torque car for good launch hookup and many of them hop like a bunny. .


Every single 04+ GTO I have seen run at the track is miserable off the line for that very reason. Wheel hop just kills them. They run hard and I like them but off the line - ouch.

Not really looking for straight line. Want to turn more then accel..

Anyhow, what I was planning on doing was doing a 3-Link on the current setup, and running that, while I work on do a totally custom frame/susp. setup.. I've also got a lead on a C5/6 Rear susp...

-Todd

C5/C6 would be much more worth the time/effort than the GTO setup, especially if you retain the transaxle and torque tube (although bye-bye back seat...)

That's what I was thinking... :clonk:

Not too worried about the back seat, I was looking at doing a 2+2 setup possibly...

-Todd

That's what I was thinking... :clonk:

Not too worried about the back seat, I was looking at doing a 2+2 setup possibly...

-Todd

I'd just count on a "2" setup. It takes a lot more room inside the vehicle than you may think. In fact, here's build pics of a friend's Camaro that Wayne Due did a C5 transaxle in...

http://www.waynedue.com/web/cars/GaryGutherys1968C5Camaro/index.html

You may be able to use late model Camaro "mini-bucket" seats in the back but I wouldn't expect anyone over 8 years old to fit back there.

I'm still thinking about this route too, although a well-sorted 3 link car will handle really well and be more durable in the end. The transaxle setup will provide weight distribution advantages, however installation in the frame/floorpan areas and exhaust routing will be fun. And don't forget the additional "fun" down the road when it comes to clutch replacement...

Damn....
Didn't know the setup was that big. I think I need to reconcider my options. Don't really think the trouble is worth the effort... I guess the ease of a 3-Link compared to a C5 swap will allow time for the "fine tuning"

-Todd

This may sound like blasphemy but I have pondered if you could fabricate a mounting setup for an IRS setup from a later thunderbird to fit into our Chevelles for a pro- touring perspective. I see them in the U-pull yard and they sell those parts so dirt cheap.

This may sound like blasphemy but I have pondered if you could fabricate a mounting setup for an IRS setup from a later thunderbird to fit into our Chevelles for a pro- touring perspective. I see them in the U-pull yard and they sell those parts so dirt cheap.
Bunny bunny hop hop!

Ford is a lot newer to the IRS game than GM is, at least with respect to higher power level applications. It is interesting to compare the IRS design that GM has evolved to on the Corvette over many years with Fords more recent creations. One area in particular that is dramatically different is the differential mounting. Both use 3 point mounting but the spread between mounting points on GMs setup is huge compared to Fords. This goes a long way towards stabilizing the differential and preventing oscillations that are the root of wheel hop.

I have wondered what it would do to my Mustang IRS wheel hop if I converted to a wide rear differential mount. The challenge is getting it to fit in there.

Bunny bunny hop hop!

Well, that not the blasphemy I was thinking of but from a movie. Can you tell its Friday?

Look, I don't think it should be a sin, just for saying "Jehovah"

You're only making it worse for yourself!

Making it worse? How can it be worse? Jehovah! Jehovah! Jehovah!


The only reason I bring up the mid 90' T-birds is that you can find them in the salvage yards with disc brake and posi at very affordable prices. Ever find a corvette irs priced cheap?

If you have access to the gto rear for cheap, have some fun and be different. That's what hot rodding is about to me.

I dunno... what do you consider expensive?

A lot of the Mustang Cobra guys hate their IRS so much they rip it out and sell it on Ebay. Prices vary a bit over time but you can easily pick up a '03 or later with the 3.55 gears and stronger half shafts as a complete sub-framed module for under a $1000. Probably a lot easier to make mounts for a sub-frame than all the individual components.

Well, that not the blasphemy I was thinking of but from a movie. Can you tell its Friday?

Look, I don't think it should be a sin, just for saying "Jehovah"

You're only making it worse for yourself!

Making it worse? How can it be worse? Jehovah! Jehovah! Jehovah!

Monty Python's "The Life of Brian" :thumbsup:

Keep in mind there are adapters out there that allow you to use the C5/C6 IRS but maintain a stock position tranny and run a standard driveshaft back to the rear end, allowing you to ditch the torque tube and rear mounted tranny. That makes things a lot easier to package and probably would allow you to keep the backseat.

However, I'd prefer to keep the torque tube / transaxle setup for weight distribution reasons.

IRS is cool, but I think you'll find a good 3-link with a cambered housing 9" rear end will handle a lot better than you might think.

I was (and still do) thinking about a C5/C6 transaxle and IRS swap but I'm probably going to go the cambered rear 3-link route now.

with the C5/C6 adapted IRS with standard tranny, I assume that they use an upper control arm also, so i also assume custom upper frame rails will be needed also?

Most all of the hop associated with the GTO rear is due to the rubber-mounted bushings for the third member and supports. They offer urethane mounts that eliminate the hop, at least in the 10 second GTO's I've seen videos of. Depending on power level you may need to swap axles and stub shafts for stronger units also. I just did all these upgrades to my 05 GTO and it was about $2K to upgrade it.

My opinion is it works fine for a GTO and weight-wise they are similar to a Chevelle (3700 pounds). But I'd probably look for something stronger unless you were staying at around 400-450 hp or so.

Jody

IRS can be a mixed bag and people either love it or hate depending on what they want out of the car. If you criteria is 60' times you would probably hate it. It can be very tough to tweak and tune an IRS in a high torque car for good launch hookup and many of them hop like a bunny. Many of the Mustang Cobra guys swap out the IRS for just this reason. It kinda funny though because one of the benefits of IRS is no lifting of the RR tire from torque which would be a good thing otherwise.

The IRS in the Cobras uses a cradle that mounts in using many of the mounting points for the factory 4 link which has rubber bushings at those points. Plus rubber bushings are used in the a arms which mount to that cradle. The adapted IRS has to many rubber bushings in it causing the hop.

IRS is not the best drag setup but you can 60' them as well as most solid axle street/handling oriented cars. C4/C5s can pull 1.6s with DOT ET streets or drag radials with minimal work. The 3rd gen RX7s also 60' very well.

Stick axles can also handle virtually as well as an IRS but the IRS will ride smoother in most examples and will be more forgiving on uneven surfaces based on my experiences with a 93 and 00 Corvette and a 94 Z28 using most of the standard upgrades

I should take one of the spare T-bird IRS's I have and see how it matches up to my 70' Malibu frame since Its currently sitting with the rear differential removed. (My daily Driver is a 96' T-bird that runs mid 13's). The thunderbird IRS is mounted to a subframe that bolts to the car with 4 bolts and there are quite a few Cobra Kit cars running around with Tbird IRS's on them. There are Poly bushings, bigger brake kits (cobra 11.65 rotors, stock 92+ thunderbird rear calipers, and relocation brakets) The only thing you would need is Hubs off a IRS mustang for the 5x4.5 pattern or redrill the T-bird ones 5x4.25 to 5x4.75. Also the 93-98 Lincoln Mark VIII's use the same rear IRS setup except the lower control arms are different since they use Airbags instead of coil springs. There a few guys into the 10's with IRS thunderbirds cutting 1.5xx 60ft times so they CAN hook decent at the track.

At the Portland Swap Meet (this weekend) a local fab shop had one of the T-Bird IRS set-ups on display that they were putting in an early 70's Firebird. They had narrowed it two inches for their application,which may or may not be required depending on a persons particular requirements, what year Chevelle is being retrofitted and wheel offset choices. I didn't take any measurements or photos of the displayed unit (like an idiot) but it sure did look good.Stopped me dead in my tracks. I liked the fact that it was a bolt in affair, all the geometry was figured out, just configure the original (or probably tube in my case) frame to accept the whole new assembly.I'm doing a 64 2dr wagon that will never see a race track or drag strip. Maybe once for the "Oldies but Goodies" day at the drags but nothing worth designing the car for. A local guy put a late model Covette running gear in his 57, while at a show I asked him how he liked it and how did it drive. He said that he really liked the way it came out and that it handled like "a lazy Corvette".Well, that is about as "perfect" of a description that I could ask for, for what I want my wagon to handle like. While at the swap meet I also saw several Corvette IRS units for sale. They have that nylon/plastic monoleaf spring for suspension? How does a guy adjust ride height or stiffness once it's under his car? Another nice feature of the T Bird unit is that it has a place to mount the coil spring/ air bag. I'll admit the thought of a Ford suspension in my wagon was a bit disturbing but so far seems to fit the bill unless LateNight72 can get the GTO set-up to work. I'm not stuck on any particular IRS but, IRS seems the way to go for the direction I'm going. By reading the posts in this thread.I'm not alone and will help this movement in any way I can. I own my own fab shop and can build what is required to make these cars handle.

Max, was there any interesting Chevelle parts for sale in Portland this weekend.
The ride height can be adjusted by using shorter spring bolts (through the end) or longer ones to lower the car. The older metal springs, you can remove a few of the shorter leefs. The plastic spring comes in about 6 or 7 different load bearing lbs.

[QUOTE=65Camino]Max, was there any interesting Chevelle parts for sale in Portland this weekend.
Oh, not really. One guy had some NOS 64-65 Wagon roof racks though, which is a bit different than the norm. I wasn't looking for anything special so I surfed it pretty fast. I almost didn't go this year, but you know how that little voice can be. Thanks for the corvette rear spring rate adjust tip. Are there there any photos or posts of someone putting a vette rear in a chevelle or any other IRS for that matter. Even if the project was never finished something may still be learned. This can't be that exotic.