2nd Gen IRS

[jp455]

Hello all...followed project RePeeled closely and was waiting to hear some news on the Heidts bolt in IRS. Anyone have any experience bolting this on and/or driving in a car with it? The only drawback from looking at pictures are the the inboard brakes, but I guess some good cooling ducts could solve that, and the cheap looking shocks which of course can be changed. Another thing is, the geometry has to be compatible with the front end. Any thoughts?

[732ndgen]

d@z customs has that set up in his car.bumped into him at road america and that system was insane looking,their were more people looking under his car than looking under the hood. www.dandzcustoms.com

[srh3trinity]

d@z customs has that set up in his car.bumped into him at road america and that system was insane looking,their were more people looking under his car than looking under the hood. www.dandzcustoms.com

That is the project RePeeled that he was referring to. It looks like a cool setup, but I also was not a fan of the inboard brakes. It looks like they have a universal kit IRS on their website if you flip through their catalog.

[jp455]

Yeah those brakes look annoying. Mainly because if you get a front caliper that isn't compatible with the rear one and th master cyl. then you need to use a ton of bias valve on it. I'd rather be able to buy a caliper set and have a balanced setup with out one. Is this the only 2nd gen setup out there?

Any comments on how it drives/rides?

[MrQuick]

I think everyone gave up on the IRS deal since there are so many affordable link kits out there. I mean whos gonna pay $7K or higher for a non Jag based IRS kit?

Vince

[jp455]

I would think if you want the ultimate in handling you would go with the IRS. Is the difference not that noticeable? Although I must say that the whole thing about a solid rear being jumpy over bumps can also apply to cars with IRS. I had an S2000 that would step out a bit going around bumpy corners.

So if we stick to this ultimate ideal, which of the systems manufactured out there would be the best right now?

[MrQuick]

very true but it depends on fitment design that doesn't compromise the geometry.

I know a few leaf sprung cars that could keep up with a C5.

There would have to be a very large budget to engineer a system to fit a 2nd gen body properly. I am afraid more than the average hobbyist would be willing to pay. I can see a full frame job but not a unit using existing frame and floor.

Unless you have a machine shop with CNC equipment that would donate time, Heidts is the closest you will get to a bolt in IRS kit.

Straight axle....
With performance in mind I would go with an AME system since LD is now out of the loop. Also don't forget the system that Jake rod shop has going.

I believe there is a thread on the best available system.
Vince

[dipren443]

Had a long talk with Marcus at SC&C about this very subject once. New frame rails... That is what is needed for a proper IRS in a second gen. Narrower and higher up than the existing...

[MrQuick]

Fully fabricated system or C5/C6 based?

Vince

[srh3trinity]

The Cuda on Bullrun had a 350z IRS in it. Has anybody seen one of those outside of the car? Brakes might be an issue and I am unsure of the physical size.

[Bryce]

if we are throwing out ideas... what about a viper IRS?

[MrQuick]

Viper would be perfect but its big bucks for the parts. It would easily be a $7-8k job. Way too much to mass produce. Customers just aren't willing to pay that.

You could do it cheaper with C5 uprights and make your own arms.

We contemplated doing it to a 70 years ago but after all the parts, did the math and the budget would be insane, we just aren't there yet.
maybe if the economy gets better.

Vince

[jp455]

Vince I actually have been mulling this over for a while since I saw the Heidts system and then saw the full frame that Schwartz is doing. I thought maybe the rear of the frame could be changed to accomodate an IRS. That way you could install an actuall performance IRS and not one that was designed in the 60s. For production I would think the Viper system would be very expensive, but as a one off getting one from a wrecker shouldn't be too bad.

Although I have to say...the last scratch built car I worked on we did the uprights, A arms, etc etc...and it wasn't thaatt bad cost wise. Definitively not cheap but not as insane as one would think. We even had the A arms welded up by a place that does Indy car arms, they had the aerofoil shape and everything! Heres a pic of the full setup.





In any case...really wonder if the Schwartz frame/IRS combo is even possible. On a bit of a side note....nobody has riden in a 2nd gen with the Heidts system then?

[MrQuick]

Good stuff Manuel,

I think we talked about it 4 years ago?

I'd love to do it but had a hard time convincing a customer to take on the budget.

The Heidts system is new so I don't believe so. Have youy spoken to the guys that built Re-pealed?
Vince

[jp455]

You're right Vince, but it wasn't that long ahgo, more like 2 1/2 3 years ago. I haven't asked the repeeled guys directly, guess I wanted to see if there was a more general feel for the thing. Plus I also wanted to see what peoples opinion on installing IRs systems in the 2nd gen is since you rarely see it even though you see it on 1st gens. Maybe I'll look into designing something myself with a Corvette upright or something. I used to work at Mosler too, so the rear hub and all is there, even with center lock, would just need to figure out the frame to attach everything to.

[exwestracer]

The Cuda on Bullrun had a 350z IRS in it. Has anybody seen one of those outside of the car? Brakes might be an issue and I am unsure of the physical size.

We are putting a 350Z setup in a student's 78 Camaro right now. He's on this board, so maybe he'll throw some pics up here as we go. It does require some subframe mods to get the crossmember high enough in the car. Other than that it's an amazingly good fit... rotor to rotor width is 1 3/4" wider than the stock 10 bolt.

[silver69camaro]

The Viper suspensions are awful, I wouldn't bother with those. Solid axle cars can handle just as well as a IRS (presuming it's designed well) system, although they can't, in theory, ride as well due to a large amount of unprung weight. Typically IRS setups just aren't worth the extra cost.

[jp455]

Ray-Whats the guys name the 350Z system is going into? I really would like to see that!

Matt-I agree on a track both systems combined with our cars wouldn't be very different if at all. But driving on a bumpy road I bet the difference would be noticeable if the IRS is well tuned shock and spring wise. Plus its a great exercise to apply my skills in designing and building a system like this, even if it is a lot for that trick factor!

[mikedc]

IRS won't make a real difference on any decent track.


Windshield wipers won't help on the track either. But that doesn't necessarily make them a bad investment.


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[exwestracer]

Ray-Whats the guys name the 350Z system is going into? I really would like to see that!

Matt-I agree on a track both systems combined with our cars wouldn't be very different if at all. But driving on a bumpy road I bet the difference would be noticeable if the IRS is well tuned shock and spring wise. Plus its a great exercise to apply my skills in designing and building a system like this, even if it is a lot for that trick factor!

I'd talked to him about this board and he knew all about it... I'll find out tonight if he's a member here. It will be a week or so before we're back in the shop and working on it again. He IS installing a full rect. tube chassis into the floor to lower the car, so the mounting points will all be on new metal; however, the Z subframe mounts line up exactly with the width of the stock rear subrails, just not high enough in the car...