I've been being a good boy by searching the boards for info but have run into the issue of not finding a direct link that explains just what are the suspension differences in my 1988 Camaro Iroc-z.

Why does the Iroc's sit lower than the Z28?

What the focus is for me is that next week I go in for a major spine surgery where the surgical team will scrape out what remains of my bad lower disc and then install a brand new titanium disc.

The CAMARO PERFORMANCE HANDBOOK gives a pile of info including different spring rates, and a recomendation on Chisolm's custom lower control arm.

Because of my back, I will certainly need the lowest spring rate there is and let the strut take the pounding.

I tried to run a search on the F2 suspension marking that GM uses to signifie the IROC and keep coming up with nothing. Can someone tell me where I'm going wrong?

The goal for the Camaro is to occasionally run hot laps at my local Infinion Raceway (where NASCAR boys come once a year to tear up the road course.), but yet be able to jump in and head out through Nevada to hang out at the family farm on the Snake River (Twin-Falls, Idaho).

Question: How low is the IROC compared to the others. What design item makes them lower? Given this, how much lower can I go where the potholed, torn up Nevada highway wont tear me and my ride up when I'm doing 140. My Lexus SC400 takes it like a dream.

Has anyone with a back injury found ways to set the suspension up that works well for them? Hopefully I"m being somewhat clear stating my needs. Blackie, the 88 IROC 5.7 TPI
Take Care, Nitro

The Author of the CAMARO PERFORMANCE HANDBOOK suggests that there's no reason to not have a cushy ride with aggresive suspension as back up with only a couple adjustments away.

Teach Me Please. Nitro

 

The IROC-Z suspension is FE2 and I think Z28 suspension is F41 (not too sure on that one). Try a search on FE2 and you'll probably get alot of information. From what I know the main differences were springs and swaybars, though I guess the strut/shocks might possibly be different. I cant think of any suspension setup that would work good going over potholes at 140mph, but if you are looking for a compromise between ride comfort and performance I think progressive rate springs would be the way to go. So either the Eibach Pro-Kit or Sportlines, and I think there are other progressive rate setups out there too (Hotchkis? Global West? not sure). Match those up with the best struts/shocks you can afford and replace all the bushings in the car with OEM replacement rubber (since you want comfort). The Camaro Performance Handbook is a good read but I personally dont think they are being realistic about having a cushy ride and agressive suspension setup. Its either a compromise between the two or its an extreme at one end, not both. Unfortunately for us, one of the major factors that affects both comfort and performance, the spring rate, is usually not something that is adjustable.

 

I'm sure I've just discover ed why I couldn't get any search results with the F2! Thank- you for responding AND for your input on the Camaro Handbook. I know I'll at least have to do an adjustable shock setup so I can do a bit of switching on track days. It's to bad I can't mimic my woman's G35. It has the sport suspension and is surprisingly a mixture of that suspension tauntness and yet, a low speed cushion feeling.

I also wanted to figure out how to lower the front a bit more, but need to understand first why the IROC is the 1/2 inch lower than the Z setup. Again, thanks for putting me on the right track! Nitro

 

Have you ever thought about Air Ride Suspension? Just a thought. Its suppose to handle well but have a nice ride, not harsh. Its something i wouldnt mind having but the money has to go elsewhere right now. Its kind of expensive. I know kandied91z and a few others could give you more information......jt

 

I am SO open to suggestions. I've been watching and reading up on the air stuff. It surely is pricey, but like everything new, it should start creeping down in price eventually (I hope)! Nitro

 

None of these is really an option.

Generally, for a suspension design, the faster you go the stiffer spring you need to keep from bottoming on a serious bump. Forget the way you phrased the question since if you hit the average pothole at 140 you’d destroy the tire and wheel.

Both my brother and I have had assorted back problems (spinal stenosis runs in the family so we’re prone to lower back injuries. His is more extreme then mine and he ultimately broke 2 vertebra in his lower back and had I think 3 or 4 of them fused together, disks completely removed. I’ve and enough lower back compression from a combination of my lower back being narrower then it should be + weight lifting (and being over 300#) that at least 3 of my disks are less then 1/3 the thickness that they should be) and both of us own very stiffly sprung project cars (and at one point I had a daily driver 3rd gen that saw regular 6-13hr road trips that had 9xxlb springs in the front, koni yellows…)

That said, you’re barking up the wrong tree in 2 ways. First, what you want to do will never work in a 3rd gen. The trick to making the front suspension work is to keep suspension travel to a minimum and then adjust the alignment to a compromise between what you want straight line and in the turns, because there isn’t any useful camber gain in the front suspension. To do this YOU HAVE TO run stiff front springs. Nobody makes progressive rate front springs for exactly that reason, they wouldn’t do anything but give you a car with crappy handling.

The rear spring rates tent to be quite low on them, but relative to the actual weight that they’re supporting they’re actually quite stiff. Here the simple fact is that the solid rear axle is a lot of unsprung weight to control. On a positive side suspension travel isn’t as big a problem so you can get away with progressive rate springs to give a supple ride over minor bumps and in transitions (which is exactly why I hate them, that softness in transitions equates to numbness in the suspension feel when changing suspension loading.

Yes, your Lexus gives a nice ride and feels competent, and that is basically a 2 part thing. First the rear IRS significantly decreases unsprung weight allowing the the suspension to control the tires over bumps with softer springs, less shock dampening…, and secondly, the thing is significantly heavier which absorbs a lot of the road bumps… The fact is I would seriously doubt that putting the comparable tires on that and even a base suspension 3rd gen would the lexus out handle it in any category, depending on suspension condition, alignment settings… it might feel like it would but actual hard numbers would show that it didn’t. Hey had engineers spend a lot of time making it feel that way.

So what’s your solution? Well, first you need to redefine/clearly define what level you really expect this car to perform at. If you just want it to out handle that lexus then you can literally put the softest v8 RS springs in it, some decent sway bars (shouldn’t add bump harshness under most conditions but still allow decent handling), shocks/struts and put a set of good tires on it and call it a day.

The second way that you’re barking up the wrong tree is that I don’t think that you need to compromise handling at all. Like I said, both my brother and I have back issues and both have cars that have very stiff suspensions that weren’t compromised at all for handling. My formula is tamer then my ’83 TA was, and it still has eibach pro springs in the front and 200lb specific rate springs in the rear, koni yellows usually at full hard, 36/21 or 24mm sway bars (which I actually think are too hard to work right but they were on the car when I got it and I haven’t done anything about it), and I use it as a daily driver a lot of the time. The 2 things that I would look at instead are seats and tires.

If your seat doesn’t support you well then your back will hurt. The seats probably makeup more of the ride quality end of suspension feel then most people give them credit for. Make sure that they’re right. In my brother’s case his “race car”/toy started as a 4 door with some fairly plush power seats, and it still has them. In the case of my ’83 TA for a while I screwed around and found that on bad days just putting something like a book behind my lower back made a night and day difference in comfort. Eventually, in the interest of comfort AND autox and road racing I took the seats apart, reinforced them where they needed to be (I actually added 9x6” lateral supports to the seat base to prevent me from sliding side to side inside the stock support bolsters)… You may just have to look into replacing the seats with something else that works for you.

Tires- skip the low profile tires. Real world they’re not actually giving you better handling, and they are making your ride much more harsh then it needs to be. With a given tread compound and proper tire construction you can usually go faster on a 15 or 16 then a 17 or 18 (of course, it’s much harder to find good tires for the smaller diameter rims). I used to race my ’83 on some 60 series, 15” rim Hoosiers and when I got the chance to try identical 16” hoosiers, on the same day I lost over a second average time at the autox. You’ll be shocked how much better the ride quality would be with a decent set of 15’s or not so much so but still with 16’s, and compared to a similar low profile tire you will not loose handling ability (and even if you have to go for a much lesser 15” tire most people are surprised how little you actually loose).

 

83 Crossfire T A's post gives me an excellent framework to rethink what I'm ultimately doing. I know I am after a melding of the underpowered SC400 (which had fantastic seats for touring) and my wife's G35 (which is so damn much fun, but I'd NEVER consider taking it across state).

This IROC is definitely a play car, and is not needed as a primary transportation vehicle. However, I have no intention of it being a full track-star ride. There's just something about a V-8, duel Flowmasters, and enough engine grunt to set the backend out exiting a corner. If someone dosn't get chills from doing it, there's not much of a way to explain it so they understand.

I see now that I really do need to start with the supportive seats before anything else.

Thanks for being willing to share about your back issues- your experience is going to be VERY-VERY helpful. Thanks for the excellent input. Nitro

 

huh, G35 huh... always felt a little wimpy to me... a little better with a blower:

 

Well spank my butt and call me Sally! ( VERRRRY Respecfully Cool!!!) Nitro

 

It looked a little like this when I was done: