Ive had my Firebird for a few years now and have slowly been doing misc work to it. (Its a project car) JUST in suspenion....Ive replaced all the coil springs (from Spohn...got "stock replacement" didnt want lowering ones because NJ roads sux)...HD Bilstein Struts and Shocks.....Greaseable LCA Del-A-Lum bushings (for the front control arms)...new strut mounts (from Spohn)...new link stablizers (Poly of course) for the front...aftermarket Panhard Rod.....I think thats it. The rear sway bar ISNT hooked up...just been lazy..... I DO have Subframes for the car (Kenny Brown) but I need someone to weld them in and MONEY to pay someone to do it ect ect.... I ALSO have a STB along with LCA's for the rear waiting to go in...

Anyway...JUST as it stands right now what I have IN the car I feel is pretty "respectable" setup so far for being a street/autocross/strip car.......BUT honestly.....I dont think the car handles all that great. I think what I have IN the car now looks good on paper but in reality I dont think the car handles all that great (in my opinion). I honestly think that my 92 Cav is a better handling car with new KYB GR2 shocks and springs in the rear and WORN OUT struts strut moutns and springs in the front.

What Im wondering is once I install all the pieces I have in my basement will my car handle a lot better? Obviously any of you guys that know the in's and out's of suspensions can pretty much tell that Im opting for handling NOT comfort. The only pieces that I DONT have (suspension wise) is a "lower" STB...cant remember what its called at the moment and Relocation brackets for the LCA's. Oh yeah...forgot about a rollcage.... But other than that theres nothing else right??

Basically as time has gone by Ive driven all sorts of cars. (I work at a garage) Ive just seen a lot of cars at work that I feel handle a lot better than our F-Bodys. YES I know that our cars are the "cheap mans sportscars." Im really wondering once I install all my suspenion pieces will it be worth it? All comments are welcomed as long as I dont see "If you want a car with good handling buy a vette...ect ect" Sometimes I wonder if I should do....or rather call favors in and do a independent rear suspension setup......

Thanks in advance...

Dan

 

Your on the right track. Fist off PUT YOUR REAR SWAY BAR BACK ON. There is a reason the factor put it there. You have a 91 formula which is a good starting point. You should have 36mm front/24mm rear swaybars, which is good. Get polyurethane bushings/endlinks for them. Weld up your Sub Frame Connectors. Put on your Strut Tower Brace. The lower one is called a Wonder Bar, you can get it fron TDS or Spohn at the top of the page. You should have gotten some performance springs like Eibach Pro-Kit they don't lower your car that much and work well with the Bilstein shocks/struts you already have. Plus you more that likely need new steering components.

On a side note: Your car is a solid axle RWD. It can be made to handle VERY WELL. It's a totally different animal that your FWD Cavalier and will run circles around it all day long if you set it up right and know how to drive it. NO NEED FOR AN IRS. Waste of time and money in my opinion.

 

I would also think about getting stiffer springs than those stock replacements.

 

91Formula~

Thanks for your insite.... Yes I agree that I should reattach the rear sway bar... when I was doing the rear shocks I disconnected the end links....one link broke so I just left it unattached. Im curious why you dont like IRS systems... I just figured it "smooth out" the ride overall and would always keep both wheels on the ground while doing hard cornering... Like I said before..Im not an expert in suspenion systems....

Are the sway bars the "right" sizes for street strip autocross setup? As for the coil springs...kinda hesitant to change them again... Ive heard that you can opt for variable rate coil springs for the rear for better ride quality and for better launchs off the line. Ive read sooooo many posts on coil springs...thats why I opted for stock ones (the more I read...the more I felt that going with stock was the best setup). Are performance coils REALLY worth it? As for my steering components....I did replace the lower ball joints when I put in the Del-A-Lum bushings. Everything feels pretty damn tight with the expection of the steering box. It has a little play in it but nothing major. Ive been thinking of a performance box but havent read up on any aftermarket boxes...

Dan

 

The physics behind are IRS are for feel as well as handling over rough surfaces. over a bump, an IRS will feel softer and more stable in hard cornering. If you hit a bump you will have more surface area of the tire contacting the road therefore better control.

They are "technically" better then a live rear axle, but when you look at the straight performace aspect not by much. The primary thing when you have a live rear axle vehicle vs. one with an IRS is the comfort level, and that's about it.

There is also the fact that under extreme loads live rear axles can "sidestep" or move to the left or right. This again, does happen, but not even enough under the stock setup to affect performance or control.

It can be done and has been done, but the only thing really gained is comfort. In drag/straightline performance a rear axle can easily beat an IRS, and in cornering it really isn't worth the price of all the work and fabrication to get it done in such a manner to work any better and at even at the least function correctly.

For our cars there is a vast aftermarket of parts for the rear suspension that minimize the amount of sidestep (although in stock form it never really is a problem) and keep the tires planted in both the straightline and cornering area.

So is it worth it? Well, as has been proven many many many times over a 3rdgen with a stock style lightly modified suspension setup can easily pull more G's then any stock corvette.

 

ttt... still have questions id like answered.

Dan

 

Dan, you said a few things that confuse me. You said you wanted little to no body roll. In my opinion you need to get some stiffer springs in order to achieve that. I have the Eibach Pro springs and my car is lower, but not by a whole lot. The ride was greatly enhanced. There is some body roll, but a whole lot less than stock setup. I also used Energy Suspension's Poly end links front and rear. I watched a video of my car before and after on the autocross track. The difference was jaw dropping.

You also said that you weren't shooting for a comfortable ride, then came back with wanting IRS for comfort.

Also, what kind of tires are you using? Tire size? When I first built my car I had some Eagle's or something on it. (15" wheels) I swapped to some Ventus K102 245/45/16's on IROC wheels, and I was absolutely amazed by the diff.

Happy driving, Josh

 

Yeah that kinda stuff made a nice difference for me, IRS "generally" hold better in turns while live axles typically transfer torque better.

Each tire on an IRS reactes independently of the other one when they hit bumps (rear axles both move to a certain amount)

Basically, each has they're ups, but for the price to get one to even function in a thirdgen, not even better then the stock axle setup, isn't even worth it.

 

Where to begin....

Springs~ Kinda hesitate to change them (again) because of money issues (just dont have the money ) and because my car has trouble with scrapes in its current ride hight now. BUT I will keep the idea of changing the springs out in the back of my mind.

As for the IRS vs. live axle.... I wasnt sure which direction to go with the car in general. (Sell it as is and cut my losses...modify the suspension more and "feel it out"...ect ect. After reading what you guys have posted Im just gonna stick with a live axle.

As for tires....front tires have seen "better days." Yes I know....Im sure it does wonders for handling. lol As for tire size (front and rear) Im running 245 50 16's. When I bought the car I opted for BF Goodrich KDW's...

Thanks for your the info and interest in my post.

What Im STILL wondering about is if I should keep the stock sway bars in there or opt for different ones. Like I said before the car is being built for autocross, street and strip. Obviously I cant have the best of all three worlds...just would like sway bars that are "good" for all three... I guess "all around good" sway
bar(s) is what Im looking for. My other question is what experiences/thoughts do any of you guys have with performance steering boxes...

Thanks again for responding..

Dan

 

when you figure this one out let me know.. im not too concerned with comfort either, but with the "bang thrash" roads around here anyone outperforms me... a minivan passed me around a turn in the rain last night, and i know if i was going that fast on that bumpy *** road my rear end would have been all over the place
i dunno this stiffer is better logic applies great when your on smooth roads.. but heck i can barely find any around here

a friend picked up an 86 camaro SC a couple weeks ago and I can feel the body roll, but i found myself driving faster in that car then mine...
its like, maybe the stiffer suspeision really is helping your car keep its balance, but since my car is throwing me all over the passenger compartment.. it takes away any more control i would have gained over the car

anyways, just my thoughts

 

ttt...

 

Stock spring rates are your problem. You need to bump up aprox 200lbs in the front minumum. And those tires are not what they are cracked up to be. Get some better performance rubber.

Otherwise, hate to tell you, ain't nothin' anybody can tell you what you want to here. You aren't going to handle at all with that weight transfer and those tires.

 

ok..thanks for your input on springs and tires vsixtoy. I personally am pretty happy with the tires so Im gonna keep 'em. Springs.....eh Im not too worried about them right now. Maybe in the future I'll change them out but not now. What I REALLY wanna know is if I should change out the sway bars......


Dan

 

Dan, My appoligies. I just reread the tires you have and saw they are KDW and not the KDWS (The KDW's threw me). KDW are very good tires.

I am assuming you have the 36/24 bars? If so, you do not ever really want to go larger than that on anything. Bigger is not made anyways other than Spohn's 25mm rear-you would not even feel a difference between that and your 24mm with the springs you have. Besides no matter what, you should never put a 25mm rear bar on a V8 car. Most full race opinions would perfer about a 22mm on rear with a stripped down car with heavy rate springs. Your only option to get the car to handle better into, through, and exiting corners is to put heavier rate springs on it.

 

huh? typo maybe?


Im not really sure what bars I have on there... Im assuming they are stock so that would mean they are 36/34 right? The only thing I can tell you about the bars is that the front was is "big." How would I go about finding out? a ruler???

 

Try buying a cheapo plastic vernier caliper from discount auto parts, that way, when you kill it, it won't cost much. That's the most effective way to measure the bar.
http://www.fl-thirdgen.org/blacksheep-1/camaro.mov
This is my baby.

 

a neat way to measure bars is to use regular end wrenches...1 inch open end wrench fits over a 1 inch bar nicely

 

how many mm equals 1 inch?

 

25.4 mm in one inch.

 

BFG KDW- http://www.tirerack.com/tires/tires....omCompare1=yes

BFG KDWS- http://www.tirerack.com/tires/tires....omCompare1=yes

Don't let Treracks customer rating fool you, that is not any kind of track time comparison results, just customer survey of that tire alone. There are crappy passenger tires getting 9's and 10's survey rating on their site. What you need to look at in a true handling performance tire is actual track test survey's. None are shown for the KDWS tires because they are crappy in comparsion to a good handling true performance tire. KDW tires are very good, but not great.

 

The suspension pieces that you already have seem like a pretty good start. Upgrades to the rear suspension would go a long way. I agree with vsixtoy as well, stock springs will not be adequate for what you want to achieve.

One last note: I would recommend figuring out exactly what you will be doing with the car whether it would be street, strip, or autox, and focus on a buildup geared towards that. It's dang near impossible to get one setup to do all three. Just my $.02

Damian

 

If you don't want to get new springs, cut the ones you have. Thi s will lower the car and also increase the spring rate. I cut a coil off the front and 1.75 "dead coils"off the rear. You might want to start smaller so you don't cut too much.

Put all your pieces on, especially your swaybars. They are torsional springs that keep the car flat during cornering. Also replace all the bushing with new poly.

3rd gens are deceptively good handling cars, some don't feel like they handle that well, but really do. Kinda like LS1's they don't feel fast, but they sure as hell are.

Also another reason smaller car handle better is they weigh less. Try and remove as much crap and excess weight you can, it really improves performance.

 

Bad Idea. springs are made specifically to hold certian weights and tightness. cutting them or compressing them messes up the structure of the spring and can be hazzardus. not to say sometimes it workds, but its not safe. specially here in jersey. if you dont have the sfc in yet i might be able to do them for you. i can weld but latley ive been pullin 100 hours+ a week at work.