GTO IRS in c10

[tomlamb]

I have been thinking of what to do with the suspension on my truck and would like to float an idea. What do you think of using a GTO rear sub assembly in our trucks? A guy on e-bay said he has a bunch of these and at first glance it looks like it may be able to work with our trucks. While I know someone like Nate or Scotts could graft them in and make them work, the big question would be how hard would it be to do so and would it be worth it for someone like Nate to make an install kit?

The assembly has 3.46 with locker, disk brakes, 5x4.75 bolt pattern, and a backing plate to backing plate measurement of 58". The front mount holes are 48" apart and the rear mounting is in the center behind the dif. The driveshaft connects through a rubber bushing so something would have to be done to connect it to a standard U-joint. The GTO weighs ~3800Lbs and the assembly is designed for a 400HP LS2.

So the questions are:
Will it work without a massive re-engineering effort?
What ride heights could be done?
Would anyone be interested?

[Wild83C10]

Killer price. $300, damn! I think the complexity would depend on the dimensions and where everything would line up with the frame.
You would need to z the frame and build some crossmembers to pickup the mounting locations. Then build some spring pockets.
I don't know if it would be worth it, unless you are looking for something different. You would probably improve the ride quality and maybe improve handling. I don't think it will help you get the truck any lower.

[tomlamb]

For myself, I am not looking to lay frame, I am more into the handling side for every day driving. Something like a 3-4" drop is the stance I like but I'm not sure why you said a frame Z would be needed. I agree some cross members and spring pocket or coil over would be needed, but doing the Z would take the bolt on Kit aspect out of the options and I would like to keep the bed standard. As I am not very knowledgeable on suspension fabrication, why do you think a Z would be necessary?
I do like the something different part, but also the disk and locker for the price looks good.

[Wild83C10]

I said z-ing the frame because I figured you would want to go low. With a 3-4 inch drop you might not have too. Like I said though, it is really going to depend on how everything lines up.
For that price though it may be worth getting it to see how it fits under there. I would see if you could get some dimensions first.

[tomlamb]

wild83c10 Thanks for the tip.

Would anyone else be interested in this type of setup or is this a hair brained idea?

[N2TRUX]

Originally Posted by tomlamb

wild83c10 Thanks for the tip.

Would anyone else be interested in this type of setup or is this a hair brained idea?

It's not that it's a bad idea, just that as far as I know it hasn't been done. At least by anyone that posts on the forums I visit.

While the purchase price is very reasonable, you have to factor in other costs. Since it sounds like you might not have the ability to do the fabrication work it would require for the install, that will add considerable cost.

It will also require some R&D which translates to trial & error unless you are lucky enough to get it set up correctly the first try. I'm guessing from my experience on such ventures that it's not going to happen.

If you just won't a mild drop with a suspension that handles better that what you have, I think there might be better ways to accomplish that goal.

[tomlamb]

Originally Posted by N2TRUX

It's not that it's a bad idea, just that as far as I know it hasn't been done. At least by anyone that posts on the forums I visit.

While the purchase price is very reasonable, you have to factor in other costs. Since it sounds like you might not have the ability to do the fabrication work it would require for the install, that will add considerable cost.

It will also require some R&D which translates to trial & error unless you are lucky enough to get it set up correctly the first try. I'm guessing from my experience on such ventures that it's not going to happen.

If you just won't a mild drop with a suspension that handles better that what you have, I think there might be better ways to accomplish that goal.

I definitely get what you are saying. Not being a fabricator myself, trial and error install would not be in my cards. I would want someone like Nate or Scotts that are experts in suspension to do the install so that the geometry would be correct but you pose a good question, how much trial and error would someone like that be subject to? I also do like the “something different/new” concept so that’s the reason I started looking at it in the first place. Given that converting to disk, track lock, reinforcing arms or 4-bar, shocks and springs would cost $x would the GTO concept be better, and if so, how much more would it end up costing is the key question.

When I first thought about this I was thinking it would be great to have a Kit like the Dropmember C4 but given the responses thus far it may be barking up the wrong tree but I figured no harm at least posing the question

[andrewmp6]

Why not a jag irs or even one out of a thunderbird both would be cheaper.

[tomlamb]

I haven't looked at the T-Bird, I was looking at the GTO because it is a modern rear, 3:42, Disks, track lock, and designed for 400HP in similar weight. As a plus, $300 for the complete setup looked like a deal. Has anyone done this type of IRS? I have seen the Jag setup on hot-rods but I think parts would be way north of $300...

[meansting04]

It sounds like a good idea, but i had an 04 gto and these things are not strong. Always bending and breaking the stub shafts. The cvs and the halfshafts are way undersized, even if you step up to the 05-06 model year. They also have to have the craddle shimmed and aligned to work properly. If you go with a complete aftermarket lsd from kazz you are looking at 3500-5000$, most people making big power do this or solid axel swap. There are some companies like pedders that make aftermarket bushings and harrop makes a good cover all of which is expensive. Check out www.ls2gto.com. It is a good forum that can give you loads of info on these units. Just my experiece and .02 cents. After 18 months, 2 craddle adjustments, 4 stub shaft, one stuck side gear, and one twisted half shaft enough was enough for me. BTW mine only had 345 horse and torque at the wheels, it was a 6 speed with 24k on it.

[m6z]

Originally Posted by meansting04

It sounds like a good idea, but i had an 04 gto and these things are not strong. Always bending and breaking the stub shafts. The cvs and the halfshafts are way undersized, even if you step up to the 05-06 model year. They also have to have the craddle shimmed and aligned to work properly. If you go with a complete aftermarket lsd from kazz you are looking at 3500-5000$, most people making big power do this or solid axel swap. There are some companies like pedders that make aftermarket bushings and harrop makes a good cover all of which is expensive. Check out www.ls2gto.com. It is a good forum that can give you loads of info on these units. Just my experiece and .02 cents. After 18 months, 2 craddle adjustments, 4 stub shaft, one stuck side gear, and one twisted half shaft enough was enough for me. BTW mine only had 345 horse and torque at the wheels, it was a 6 speed with 24k on it.

You must of flogged the **** out of that car. lol.

I know of around 6 or 7 gto's in tulsa that are making 390-500+ rwh and none of these guys have broke a diff. Clutches, yes, but so far no one has had any problems with the rear. And all of these guys are track regulars on drag radials.

[meansting04]

after closer inspection of the pics, if you can incoperate the craddle into your frame somehow it would be better, however the strenght of the parts is still to question. BTW the rubber isolator is a big downfall due to the give, but there are companies that make one piece non rubber replacements($$$$)

[m6z]

Originally Posted by meansting04

after closer inspection of the pics, if you can incoperate the craddle into your frame somehow it would be better, however the strenght of the parts is still to question. BTW the rubber isolator is a big downfall due to the give, but there are companies that make one piece non rubber replacements($$$$)

Yeah you would have to buy the adapter so you could use a standard drive shaft. At $459 that kinda kills the budget aspect. I'm not sure if anyone else makes the adapter.

http://bmrfabrication.com/GTO.htm

[tomlamb]

Originally Posted by m6z

Yeah you would have to buy the adapter so you could use a standard drive shaft. At $459 that kinda kills the budget aspect. I'm not sure if anyone else makes the adapter.

http://bmrfabrication.com/GTO.htm

I found that Inland Empire Driveline has a 1350 U-Joint flange that will bolt to the GTO Diff for $150 so that may not as big of an issue...

[meansting04]

Never tracked the car, couple of dyno runs. The whole time i owned it i put less than 5k on the car. Just a bad lsd. Solid axle is the way to stay. The gto club i was in out here in Cali. had broke diffs all the time. Maybe we just drive them how they were meant to be driven?

[menace121978]

Originally Posted by meansting04

Never tracked the car, couple of dyno runs. The whole time i owned it i put less than 5k on the car. Just a bad lsd. Solid axle is the way to stay. The gto club i was in out here in Cali. had broke diffs all the time. Maybe we just drive them how they were meant to be driven?

LOL!! yes the rear end is the weak link in the goats drivetrain. be careful if you do buy one because there is a service bulliton(sp) on them. no recall. they just replace them if they are whinning or one leggers. and the wheel hop is terrible. and we do drive them how there supposed to be driven!!LOL

[m6z]

Originally Posted by menace121978

LOL!! yes the rear end is the weak link in the goats drivetrain. be careful if you do buy one because there is a service bulliton(sp) on them. no recall. they just replace them if they are whinning or one leggers. and the wheel hop is terrible. and we do drive them how there supposed to be driven!!LOL

Yeah. I read it all the time that their junk. But none of the guys in tulsa have broke a rear yet. All low 12's to 11 second cars. Maybe they just never hooked up good enough to frag anything? We will see this summer, a few more cars will have spray....

No one has even broke a drive shaft or the rubber coupler that connects it.

[meansting04]

I would hook great on the streets with dot slicks, but it was short lived. I had the thunk in the trunk, pegg leg, cradle adjustment problems, and leaks. Got better with a cover and great bushings. Not a bad concept just terrible parts. Keep looking for a "better"center section. Maybe a Vette's.

[Damien]

The bolt pattern in not quite 5x 4.75. High Performance Pontiac did an artical about putting GTO wheels on a Firebird and had to enlarge the holes slightly. It's only a few mm, but worth noting.

[SCOTI]

Originally Posted by Damien

The bolt pattern in not quite 5x 4.75. High Performance Pontiac did an artical about putting GTO wheels on a Firebird and had to enlarge the holes slightly. It's only a few mm, but worth noting.

This is similar to using BMW wheels on a 4.75" GM car pattern which is a popular swap for guys wanting a 'touring' look wheel on a budget. They'll physically fit but ultimately you run the risk of torsional twist causing the studs to fail (thus it is dangerous). It may not happen to everyone, but it can (and has) happened.

[tomlamb]

Well... Not much interest in the kit concept with the GTO IRS and with questionable capacity so.... anyone have any other new ideas for IRS? I know the vette system has been done but the parts are $$$, was looking at the Charger/300 rear setup but it's higher priced than the GTO, no locker and lower gear ratio and I am not sure if it’s rep is better or worse than the GTO.

[p8ntballer1911]

I wouldnt go for the crysler/dodge IRS. I own a dodge charger and theres some things i dont like about it. Some knocks when switching gears sometimes and a few other things.

[meansting04]

Originally Posted by p8ntballer1911

I wouldnt go for the crysler/dodge IRS. I own a dodge charger and theres some things i dont like about it. Some knocks when switching gears sometimes and a few other things.

Same thing with the goat. There is a lot to be desired with drive line slop in the IRS cars. This is one thing that really messed with me on this style. They spend so much time making it fit that form becomes second to the functionality. I replaced almost all of mine by the time it was said and done and 4k later i cut my losses. Its not a bad rear end, but it ain't good either.

[Frizzle Fry]

How 'bout an Expedition 8.8 IRS?

[Blansho]

Originally Posted by Frizzle Fry

How 'bout an Expedition 8.8 IRS?

That is what i am doing right now