Ok i want to upgrade the suspension on my 88 IROC. So far its got Hotchkis subframe connectors, Energy suspension Poly rear sway bar endlinks and bushings, and Bilstein rear shocks. The front seems too cushy. I think the struts are def ready for replacement with some new ones. In fact, even the rear is cushier than i want. I was looking at aftermarket springs last night and realized that stock IROC springs have a firmer spring rate than most aftermarket so springs is probably something i wont touch. So i guess my question is, should i just upgrade the front struts as well as doing some energy suspension poly bushings on the front sway bar? The rear shocks were already there when i bought the car so i have no idea how many miles they have on them.

 

One thing you can do is search for a thread in this board titled "Lowering/Making an F-body handle." You'll learn a lot from that.

You are correct, the stock IROC-Z springs are among the stiffest available, but the springs you have on your car are probably not new and have sagged a little by now. This means they are softer then the advertised spring rate and all ow more of that cushy feel you describe. Many people wait to upgrade to Koni's due to the adjustability, high performance aspect, and lifetime warrenty. However, since they are $68*.** for the set, people sometimes comprimise and get the KYB AGX's. That is fine for stock ride height but if any lowering is involved, they wont last long. You can also try Tokico Illuminas but I can't remember what people reported about them. Oh, another shock/strut is Belstein. They are considered equals with koni but since they dont have adjustability Koni ussually wins that battle/decision.

Another way to take some cushyness out of your car is going to be by using polyurethane for the bushings. Try to avoid poly/poly LCA's as they will cause bind and sometimes squek. I have rod/poly LCA's and have heard no squeking and can't report about any binding even with the autocrossing I do. For a-arm bushings, use the Del-a-lum stuff... second to none for a-arm bushings. Anotherthing to be skeptical of is that many people have reported the engine sitting higher in the car after installing poly motor mounts. I don't remember if it caused any driveline issues, but you can do a search to be sure.

I'm not sure what swaybars came on your car, or on it now so... There is no perfect swaybar combination. It is up to how the driver, in this case you, wants the car to feel. If you like understeer so you stay out of some trouble, install a huge front sway bar, if you want a little more oversteer, install a larger rear sway bar. Many people end up running the 36mm hollow front with either a 20, 21, or 22 solid rear swaybar. The whole idea is to base the sizes off of what you have done to the car. If you have a bunch of power, a smaller sway bar may be better for you so the back doesn't swing out when accelerating out of a turn.

A strut tower brace (STB) is also a good thing to have if you can spare the money. It prevents flexing in the strut towers while turning. The provides are more solid feel and more predicability.

When you get to changing struts, you should also consider changing the strut mounts since you'll have to mess with them anyway. Many people ditch the stock owrn out rubber bushing ones and upgrade to either Spohn or Hotpart strut mounts. They are taller then the stock units to allow more strut travel on lowered cars, and they also allow an extra 1/4" negative camber. Best part is, they use teflon lined spherical bearing instead of rubber. I went with Hotpart because they offer free shipping, they offer provide a lifetime wawrrenty, and they are about $50 cheaper... other Spohn and Hotpart pstrut mounts are the same.

There's plenty more to say, but I have to get started on my English essay now.
Mike

 

Nice!! like the info, I'm looking at upgrading suspension too. I couldn't find the thread maybe someone else will get lucky with the search and post it.
That was a funny way to end it
-edit-
I think the post is called "Lowering/Making an F-Body handle"

 

Good to know someone can use the info rattling around in my head. I left a lot of info out because of some of the things he said he has already done to his car. For example, I could dedicate a whole other post to SFC's. It's easy to learn all this info. Last year at this time I knew almost nothing about cars and how to improve on them (I did know how to change the oil! lol).

You are correct, that is the thread... I'll go back and edit my post.

I would post some more info, but for some reason I'm drawing a blank (unless you want to hear about SFC's)... I think the essay drained my brain for today...

Maybe I'll have more after school tomorrow.
Mike

Oh, about the springs, don't get the Sportlines. The rear is too soft for our cars and they easily bottom out with those springs.

To get an idea of what some of the quality parts are to use, I have...
Koni Yellows (the sports), Hotpart strut mounts, Eibach Pro-Kit, UMI adjusbale rod/poly LCA, UMI adjustable rod/poly PHB, UMI LCARB, Spohn SFC, 36mm hollow front with poly bushings and endlinks, 23mm solid rear with poly bushings and endlinks (I'll be trying out a 24 this weekend for an autocross event), and I'm hoping to get either a UMI, Edelbrock, or Jamex STB before the end of the year (if you know of one for sale, let me know).
My original rubber torque arm bushing recently fell apart so I'll be upgrading to poly there as well. Many others with heavily modded suspension will have similar parts.

I will also be swapping in a new rear (9-bolt 3.27 disk brake posi) to replace the stock piece and I hope to install a trans-go shift kit next spring. After college (only because I'll have the money then) I want to swap in a supercharged 400 small block. High hopes, I know.

And I'm only 17... What have I got myself into??
Mike

PS - Nice sig RS Reaper.

 

For the rear sway bar i have the 25mm WS6 sway...and man is it stiff in the corners. Night and day difference in cornering. The front is stock 35 or 36 (forget what was stock with irocs). I will def take all the advice given into consideration when i get the money together for upgrades..probably one at a time.
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I read up on the sportlines. Thanks for the tip. I heard nothing but bad about them. As for your 9 bolt..they never came in 3.23. Thats a 10 bolt. 9 bolt would be 3.27. Im planning on the same swap real soon in fact. I have a 3.42 but the gearing just isnt right for the automatic. I need slightly better highway gears.

 

The IROC-Z's came stock with 34mm hollow front swaybars and 23mm solid rear swaybars. If you car is a 1LE (WS6 is for firebirds) then it came stock with the 36mm hollow front and 24mm solid rear. If your car is one of the very super uber rare factory built race cars (I think that would make it like 1 of 16), then it came with an uber stiff (but heavier) 34mm solid bar for the front and a solid 25mm bar in the rear. Therefor, you either have an unbelievably rare car, your measurements are off, or you have an aftermarket 1" rear sway bar.

Sorry, about the goof up with the gear ratio; I guess my brain did give up for the night. You are correct, it has the 3.27 gear ratio.

To get an idea of how the many different sized rear swaybars compare stiffness wise, take a look at the chart below. I made that to prove to people their suspecion about how the car getting stiffer is true. Typically anything below 10% isn't a seat of the pants difference.

I'm working on making a chart for the front bar, but I have to figure out how to accuratly measure the wall thicknesses. More importantly, I need to find time... the school work and car parts just keep coming.

 

My memory is bad. Its got a stock from sway which would be 34 as your saying. Im pretty sure that the rear is a 25mm though seeing as how i got one inch poly bushings and they just barely fit on it.

 

Good thread. You seem to be on a good start. Another option on the rear LCAs is something like what I've built for mine. You can see them on my CarDomain (click on my signature picture). Like has been said, alot of the choices with sway bars is trial and error. My car had a 21 and (being pretty dumb at the time) I trashed it. I really regret doing that. I have a 19, 24, and 25 rear and 36/34 hollow. I guess what I'm saying is you can never have too many to play around with.
On a side note, racing geek, I think you'll like the 24. I've not gone any smaller, but it seems to compliment the KONIs/Pro-Kit...at least on my car. I like the spread sheet with the sway bar info on it.

 

Did you want a 21mm rear bar? I can pull one from the junkyard near me.

subroc, if you measure the front swaybar and find that it is infact only a 34, I have a 36mm hollow front bar that I painted black that is for sale. Don't worry, I didn't put like 20 coats of paint on just so it measures to be 36mm, it is a true 36mm. I only painted it because I was painting the 24mm rear bar I have and figured why not... I have the stuff out so I might as well do both.

One of the guys I look to for advice on driving techniques drives a 69 Stingray (built motor, crazy suspension, huge brakes... amazing car) and he told me I should try unbolting the endlinks of the rear sway bar for a couple runs. Now, he has never owned a thirdgen so I don't know if I should take that with a grain of salt or not. I'm thinking the rear is definitely not going to break loose, but I'm also wondering if there is going to be a lot more bodyroll which means transitions through the slaloms will be slower. My plan so far is to install the 24 rear bar and just bring tools along to the race to unbolt the endlinks. Any comment 91_5.7_TPI?

Feel free to post the picture of the chart in other threads. I figured people can save it to their computer for future referance.

Mike

 

I'd like to get one at some point, but I don't have the extra money right now.
I've not heard of that, and I'm not entirely sure of the affect it will have. I'm pretty sure it would really increase the body roll, making the car harder to control. Only one way to find out though. Just be careful if you try it. I'd just stick to leaving attached, if it were me.

 

Race Geek i would be interested in that sway bar depending on how much you want. PM me if you want and we can talk more.

 

To 91_5.7_TPI:
If your ever looking for a 21 (or other size), just let me know. I go to the junkyard often enough that it wont be any trouble.

He isn't running a rear sway bar on his car, but then again he has roughly 640hp and his car really likes to oversteer. After reading your "be careful" comment, I'm thinking I'll bring zip ties along to hold up the rear sway bar so it doesn't want to swing down and jack up the car or drag on the ground. I will only have roughly ten minutes to unhook the endlinks before I get to make my next run. I'm thinking if I don't spend time jacking up the car, it might be possible to make a run without it. I'm actually looking forward to this experiance...

To subroc:
Private message sent. Waiting for shipping info so I can provide an accurate quote.

 

You don't need to remove both of them. If you just remove one the bar will no longer be doing anything but with the other link still attached it will keep the bar from flopping around.

 

I'll let you know when I have the cash to spare...might be in the spring, when the local auto-x reopens.


My stock sway bar 'removed' itself once in a hard turn. It was before I became car-savvy and didn't know the bushings were essentially destroyed. From the looks of it, the bushings were all but gone, and decided to fall apart at that moment.... talk about snap over-steer.