This is going to be my setup for MOSTLY the street, but would love to eventually try some track days where I will fine tune the adjustments with the shocks adjustments and sway bars. Basically I want my car to handle like its on rails.

Currently the car understeers badly, and would like a setup that is more neutral. I will even accept a car that tends to oversteer slightly, but I HATE how it understeers. What should I do to correct this?

1.
I have done LOTS of research and found that I want a spring rate that is linear and not progressive since ultimately cornering performance is most important. I don’t want the car to feel "floaty" when just cruising which from what I can tell is what progressive suspension feels like. If I want to have a more "relaxed" ride I will make those adjustments via the shock settings. This car is NOT my daily driver except for the very clear summer days. For those days I will just suck it up and take the abuse.

2.
Any changes to my set up (below) to help me achieve my goal of a car that feels like a go cart.

3.
I have found that the stock spring rates from the factory was somewhere in the range of 550 front, 110 rear. If the stock moog spring rates are 781 front and 118 rear (cut calculated spring rate) wont the stiff front end make my car understeer more? Can that be "tuned" out by setting the front shocks softer and rear stiffer?

4.
Can someone who has had the pro-kit and cut moogs compare the handling for me?

My Setup:

Moog 707# springs cut 1/2 coil to lower it about an inch (strictly for ascetics even though it will stiffen up the springs a little)
Moog 107# rear springs cut as much as needed to level out the car (im assuming also a 1/2 coil?)
Tokico Illumina Shocks
UMI SFC
UMI Panhard bar
UMI LCA
Front stock rubber replacement bushings
Rebuild all the steering components with high quality parts (moog probably)
Front LS1 brakes
J&M strut mount
Performance alignment (-.5 to -.75 camber, Caster 4 to 4.5deg, SLIGHT TOE in 1/32"-1/16")

Thanks

 

What part number springs do you currently have? (moog xxx front and moog yyy rear?)
What do you currently have for sway bars?

Your front A arms - you've replaced the bushings with factory rubber there?
The UMI LCA's - those are...poly? Non-adjustable? Squeaking at all?

wheel size? Tire size & brand?

 

I should have specified, all this stuff with the exception of the sfc, panhard and rear LCA have not been ordered/installed.

Sway bars: 34F/24R

Front a arms: I am undecided on factory rubber or poly

Rear LCA: solid, poly bushings, don't squeek

Tires: Falkin ziex 512 stock 245/16R

 

You're not quite going in the right direction for ultimate cornering if what you're using are poly bushings & an Eibach Pro-Kit. Thats more along the lines of a go fast in a straight line setup. Also, we need to know your budget. Are you wanting to firm up the ride or dominate at AX/RR? You're talking about a range from under a $1k to over $9k with brakes, wheels & tires, and chassis work.

First thing you'll need is tires & wheels. This is the key to a good handling suspension. Buy the absolute best tires you can afford and get a good quality wheel for the tire. If they are street tires, you need to look at Goodyear Eagle F1's, Michellin Pilot Sports, Pirelli P-Zero's (make sure they come from Italy, the US made ones aren't worth a dead dog) or another comparable tire. These are the best street tires you can buy and are about $250-$300 a tire and most of those tires need a 8" wide wheel 16" or larger, so a set of wheels will be about $1k new depending on what you get. Now, if you go to a junk yard and get a used set of 16x8 IROC wheels, you'll have saved a ton for other parts.

The second item on the list is struts/shocks & springs. The best struts/shocks are Bilstein or Koni. They run about $300 for a front strut and $100 for a rear shock. Your Tokico's look to be about a mid range item that is more geared toward drag racing rather than corner carving. As for springs, if cornering is what you want to do, Ground Control Weight Jacks are the best & only real option for corner carving. They work only with Bilstein or Koni shocks (theres one or two others I can't think of right now they work with) and the spring rate is set based on you use and what you want it to be. They are ride height adjustable and make it really easy to dial in you ideal setup. For $500, they are expensive, but if you really want to turn, there aint nothing else that does anything close to what they do.

Third item on the list is changing from a bushing to a adjustable rod end or ball & socket joint on the LCA's, TA, & PHB. Bushings bind, a serious issue for cornering. Rod ends & ball & socket joints don't bind which allows for a smooth operation through the suspensions entire range of motion. Also, having an adjustable piece allows you to dial in the suspension perfectly, especially if you lower the springs. And if you really want to go all out, throw out the PHB and get a Watts linkage. It locks your roll center in place and completely changes how the car's rear suspension operates. Its the ultimate corner carvers item.

Fourth item would be sway bars. Switching to aftermarket solid sway bars will greatly reduce body roll and stiffen up the suspension.

Fifth item is steering & front A-Arm bushings. Find yourself a good steering rebuild kit, get yourself a good set of spherical strut mounts (you already have too, J&M mounts are one of the best out there) and get Delrin bushings for the A-Arms. Delrin won't deform like poly bushings do.

Last item would be chassis stiffening: inner & outer subframe connectors, strut tower brace, wonderbar, and front lower trans tunnel brace. This should be done first before the suspension work IMO. The only other thing to be done is get a make the suspension lighter as that will make it more responsive.

Brakes are a good upgrade. Most kits out there out do the stockers with ease. Look into upgrading the rears from drums to discs. I've read that you can save a good bit of weight by doing just that.

Here's my corner carving build list. Its a work in progress, but this is what I am for sure going to use:

UMI & Alston SFC's $200 for each set
Edelbrock STB $150
TDS Wonderbar $50
Spohn 4130 TA with Del-Sphere Joint $517
Spohn RLCA with Del-Sphere Joint $239
Fays2 Watts Link $650
Spohn Sway Bar Set $329
Spohn 4130 A-Arms with Delrin Bushings $575
Spohn Steering rebuild kit $300
J&M Caster/Camber Plates $218
Ground Control Weight Jacks $459
Bilstein Front Struts $280x2
Bilstein Rear Shock $90x2
SLP ZR1 17x8 Wheels $900
Goodyear Eagle F1 Tires $250x4
Baer Track 4 Front Brake Kit $1550
Hawks Rear Disc Brake Conversion Kit $1300

All told thats $9377 without shipping, consumable small parts, the last minute I need one of this and that things, and the cases of beer for that second set of hands

 

You can do a lot of that stuff MUCH cheaper.

I got my 9-bolt with disc brakes (the 89+ disc brakes) for $350 and you can get them MUCH cheaper than that. Which remidns me, you need to add some sort of posi to the list, that's important. you cant have a corner carver when your car goes instantly into one-wheel-peel mode out of corners. You also dont make any mention of sway bars...

To the OP.... to fix the understeer I'd look into getting a larger rear sway bar. Most of the time these cars are actually prone to oversteer from what I hear, so that's a bit unusual to hear. My car is, but I run a pretty big rear sway bar. Also be careful about cutting the rear springs, they are, from the factory, progressive rate, and the spring rate goes up VERY fast compared to the fronts. It's hard to cut off more than a half coil off the rear springs and keep them in any sort of balance with cut front springs.

 

There is an ultimate handling guide on the suspension board sticky. You can down load it from somewhere.

 

He was asking about suspension, not drivetrain. That is a seperate list on its own and you can build a 10-bolt for cheap if you follow the tech article on the front page of the forum. A Truetrac, 28-spline axles, a DTS install kit & solid pinion spacer, and gears are a needed item, but then again what isn't in need of an upgrade on our cars. And I agree, you can save money on my setup, but then its not the ultimate setup. I guess the real area that is a money saver is the A-Arms & brakes/wheels/tires, but a poly bushing is not anywhere near good for AX/RR. The bushing binds well before you're get any useful range of motion out of the suspension. I chose the tire I wanted and went from there. The key to good suspension performance is tires, not how much hardware you have under the car. Also, bigger wheels allow for better brakes, which are needed for the serious AX/RR car.

And I did mention sway bars. Solid aftermarket sway bars are far stiffer than anything that came on the stock cars.

The guy who made both threads deleted all the info on them. If you can find a cached version of the thread on Google, its worth doing a copy paste on it.

 

Linear vs Progressive springs.....the trouble with progressive isn't so much bouncy while driving straight. It's during quick left/right/left/right where the weight is being shifted from side to side. Progressive springs have more of an "accordion" style, while linear are fixed....More predictable would be the word to use.

Don't worry about the front being too stiff and the rear being too soft. You'll find it's just the opposite. With Koni Yellows, I'd say 90% of people leave the rear setting in the full soft "0" position. Probably 40-50% of people end up turning up the front settings to something above full soft. I myself have so far run full soft up front as well as 1 full turn above full soft. Just a few days ago, I turned it back to full soft. There is no perfect setting for the fronts, as it depends on road conditions, personal feel, daily driver/non daily driver, springs.

I run my rear Konis at full soft "0" and have no desire to change that.

If Go-Kart like response is what you want, go for the Global West Del-A-Lum setup for the A-arms. With those there will be no delay between when you turn the steering wheel and when the car turns. Handy for those times when you need to crank the wheel to avoid something on the highway too. I see no point in replacing rubber bushings with rubber bushings. And Poly aren't going to last as long as Del-A-Lum nor will they have the performance.

Koni Yellows....Front and rear. I can't tell you how much these really transform the car. If Bilsteins are like a Corvette. Konis are like a Z06. Even for situations where you're not out for all out handling. Times like when you spin the tires and the car wants to slide around when you start to regain traction, the Konis just hold you where you want to go. It won't slosh around. They're comfier than my stock struts/shocks were. And my car only has 50,000 miles on it. Not cheap. But worth every penny. Heck, buy the rears and do them first along with springs if budgeting is an issue.

Get the 36 mm front sway bar and new bushings. You "may" want to go down to a 22 mm rear bar at some point in the future. But for now the 24 mm should be fine.

Aftermarket A-arms seem to be expensive, troublesome fit, not of much benefit (from what I've seen). Stick with stock A-arms.

For the cost of Ground Control Weight Jacks, I'd stick with Moog springs and put that money into Konis and/or a 2nd set of SFC (inner and outer)

TDS Wonderbar fits like a glove. Recommended for any 3rd gen.

Alignment looks pretty good. But you should be able to get 5-5.5 degrees with the J&M mounts and a slightly lowered ride.

I like stock height Moog springs myself. But that's up to the individual. Better ride, less risk of hitting the bumpstops, still a good performance with good struts/shocks.

Skip the poly setup in the LCA and PHB. Go for Del-sphere (Spohn) or Roto-Joints (UMI)

 

yeah the main thing i was going to point out.. was that you "chose" Tokico illumina's over Koni yellows... man.. Koni Yellow's or nothing...

 

The point Iw as trying to make is he is listing $1500 or whatever for rear disc brake conversions - he can buy a whole different axle with good disc brakes already for a fraction of that.

And you're not going to be able to plant the car out of ANY corner without a posi. A good limited slip differential is a huge part of getting traction out of a corner - if you cant get out of a corner under power you're going to lose every time. The earlier you get on the power in a corner, and the more power you put down the faster your car is around a track. Pure skidpad ability means nearly nothing in a racing context. But if all he wants to do is just coast through sharp corners at medium speed and just cruise to the next one then an open rear end is just fine.

Also, I agree with the primary investment being GOOD shocks/struts. I have Koni yellows. They, along with my T56, are probably the best single investments I ever made to my car. I would consider tubular A-arms a relative waste of money. Only reason to go with them is if you are in a situation where you're getting a tubular K-member. With some manufacturers you're required to run their A-arms with their K-members.

Also, skip the SLP-ZR1's. They look excellent, but 8 inch wide wheels are a waste. What you'll want is something 17+ inches and 8.5+ (ideally 9inches) wide. A 17x8.5 wheel cant run tires any wider than stock 16x8's, so 9+ inches is preferable. I dont have the money to spend on wheels and tires, so I havent been able to compare, but it seems like from what I read doing my own research, you want wheels/tires the same size on all corners. Going with 17x11 or 18x11 for the rears seems to give you too much of ag rip imbalance in favor of the rear end, which is great for straight line racing, but we're talking about cornering.

Some of the best, cheap lightweight/wide wheels are going to be FACTORY OEM C5 Z06 wheels. You can get them for reasonable prices... avoid the reproduction aftermarket copies. They're much heavier.

 

Very bizarre that you are experiencing severe understeer. That is not common for these cars with a factory setup, especially an IROC. I can tell you with my setup, I have very slight oversteer at the limit. This is only noticeable on the track. This may be a good place to start.

Front:
850lb springs
koni struts about a turn stiffer than full soft
stock 34mm sway bar
245/50/16 Goodyear GS-D3 tires

Rear:
175lb springs
koni shocks on click stiffer than full soft
stock 23mm sway bar
245/50/16 goodyear GS-D3 tires

 

Thanks guys LOTS of good advice here.

Couple things, someone mentioned I was going to spend 1500 on rear brakes? where did I put that. Basically the whole rear of the car drivetrain wise is taken care of. I rebuilt a 3.45 9 bolt last year with welded tubes and a girdle.

Infernal: I got my 9bolt with 3.45 for 200.

I have been reading about the Konis but have heard that lots cant really tell the difference between the Tokicos and konis, so why spend 200 more. I guess I was wrong, I may have to re think my shock choice.

87350: Yeah, its weird that my car understeers, but it does. I have attributed it to my worn out shocks, springs and steering components. The shocks were replaced at one point from the previous owner, but they are carquest shocks that are pretty much shot. It could also be that my other rear end had the 23MM sway and this one has 24. Wouldnt that play into more understeer? Maybe I will change them out.

 

Is this the ultimate handling guide? I had this saved in my favorites.


https://www.thirdgen.org/forums/susp...ng-f-body.html

 

I think it was but I think it was scrubbed by vettruck. Someone saved most of it on some download site. I'll see if I can find the link.

 

Dude I blatantly confused your post with another I had replied too. Its like the third time I've done that the past 3 days. Sorry. Ugh...

 

Not a problem, figured it was something like that.

 

I just figured I'd add this, if you really want to go all out and build the best handling car possible, look into unbalanced engineering's torque arm. BIG_MODS has their torque arm on his car. Requires some modifications to the car to make it fit, though.But it's basically the best of both worlds when it comes to a short torque arm for launches and a long torque arm for stability under braking. Otherwise I would suggest you stay with a stock, or at least stock length torque arm. My front control arms and my torque arm are the last stock suspension pieces I have on my car. Some of the other parts are stock for some F-bodies, but not on an RS, but Im sure you get the idea. Also, if you lower the car, you're going to want to get LCARB's, but I would suggest you try to avoid it unless you have wheel hop issues. You want an angle close to stock, but some LCARBs automatically set your LCA angle at an exaggerated, overcompensated angle which is great for hard launching which is what most of these cars are used for, not so great for handling. If you have wheel hop issues then you should go ahead and get some, though. But if you dont have wheel hop, leave it alone.

You may not consider braking important for handling (some dont consider the posi important either I guess) but if you're going around a track, cornering ability is all about not wasting anymore time than necessary going slow. You brake as late as possible and get back on the gas as early as possible. Cornering ability just facilitates that.

 

Here is the link to the suspension bible document.
http://www.megaupload.com/?d=HVD8N1LL
Download it, read it, read it again and maybe another couple of times. Some of it is simple some of it not so much but it'll help you understand suspension and what can be done to our cars and in what bang for buck order. eg there's no point having giant expensive sticky tires if you can't keep them on the ground. A big issue can be money. There is almost no end of aftermarket stuff you can buy. You could easily spend $10k on suspension etc. and still not be done. I'd recommend you decide on a budget and build/replace in a balanced way to fit your wallet. And look for bargains.

 

His is based of the UE piece, but he built his own.

but you are correct with the UE piece requiring modification, as well as the car, to fit in a 3rd gen. Unless you have a cage and use the "race" version that has no under car bracing.

 

And where I can I find replacement parts for 300+rwhp on a 9 bolt if something breaks in it? Local auto parts store? Nope. Try Australia. I'm serious, theres a company down there that sells pretty much the only performance 9-Bolt parts out there. They are the same prices as they were in the states, but do you even have a clue how much international shipping is for the be there in two weeks option?

I can buy any part for a 10-bolt here in the states & have it within a week and make it almost as beefy as a 9" rear. The weak point in the 9"/10-bolt rear is the C-Clip, not the diff. The S60 is a non C-Clip axle with an almost 10" diameter ring gear. Far beefier than any axle out there and you can buy a bolt in one at any website. But I'll spilt the $3k for an S60 between a built 10-bolt and a brake kit that meets my needs for a 10-bolt.

Theres about 5 far better LSD types out there than a posi. The Truetrac/Torsen style diffs are about the best you can buy under $400. They are geared LSD's. No clutches, springs, or other wear items. You'd have to strip the teeth off the gears in order to break one and you'd need more power than an LS9 powered Vette to do it. The next step up is electronic locking LSD's. They are like an ARB locker, except instead of being open when unlocked, they function as an LSD. But since they cost between $1k-$2k for that level of function and no one has room on an AX track to engage one, you hardly see them used.

Funny you bring up skid pad tests. If you have crappy tires, you won't be able to turn worth a darn on the pad. Sorry, but all you hardware is for not if you don't have the best tires you can buy on your wheels. For street tires, you're looking at $250+ a tire for the best street tire out there. For racing tires, you're starting at $250 a tire and going up from there. However, for a 1sec gain and loss of street functionality, I'll stick with the top end street rubber.

If your car came equipped with 16x8 wheels or you can find a set in a junkyard, go for it. However, not all of us have that option. My car came stock with 15x6 wheels I've yet to find a U-wrench it place within 300 miles of where I live that has 16x8 IROC wheels. The SLP's will fit without modification and are about the cheapest wheels you can find. Also, keep in mind that you need proper backspacing on a wider than 8" wheel or your tires will rub. Theres an excellent thread in the wheel & tire board that lists all this info. While you can use C5 wheels, you eat up the weight savings with spacers to get proper backspacing. So which is it: stock IROC wheels, SLP's, or another type of wheel that weighs less and needs a spacer to make it fit?

https://www.thirdgen.org/forums/whee...er-wanted.html

The same size tires on all corners is a must for AX. You'd have asymmetrical kinematics if you ran one size tire up front & one size tire in the rear. Again, tires are the most important suspension component. As to the lighter weight parts like tubular A-Arms, the less unsprung weight you have in the suspension, the more responsive it will be.

As for the de-coupled TA, yes it will fit our cars, but you need a roll cage or some awesome fab skills to make it fit as it comes from the factory. If it wasn't such a task to make it fit, I'd have it on my list. It allows the instant center of the car to move: forward under the front wheels during braking which increases the anti-dive of the car, and rear under the rear wheels during acceleration which increases the anti-squat of the car. Both of which are extremely desirable to any car, but can you make it fit? I've built 3 racecars from scratch before (as in there was steel plate with holes in it and a CAD model) and unless I want to wait 20+yrs to acquire the tools to build anything I need ever again, I'll opt for an off the shelf item that is the next best thing.

Base91, that is Deans threads right there. TONS of really good info there.

 

It was great. Sadly it looked like Dean deleted a lot of stuff when he stopped posting here. I learned a huge amount about suspension form those threads.

 

Yep, Dean had great advice.
I followed his ultimate guide in my build: https://www.thirdgen.org/forums/susp...g-vetruck.html

Agree, Koni's are best. The swivel weight jacks are great and very inexpensive and you can turn the bolt inside the engine bay! Lots of work & welding to get them in, though.

 

I got gears for $200. Ratech sells gaskets, bearings, shims, solid spacers, etc. Even the carrier can be machined if the cones bottom out, but at the end of the day it's still a $200 junkyard rear end... you can get a whole new one easy if you dont want to spend the money replacing broken parts. Australia isn't the only source of 9-bolt gears. My 3.70 Yukon gears were I think... $190? Around $200 shipped I believe. 10-bolt gears are cheaper, but I didnt want to risk blowing up a 10-bolt with a T56. At my power level a 9-bolt will hold up a little better, but Im not making enough power to need a 9 inch/12bolt etc. The only thing I think you'd have to go to Australia for is new carriers and NEW posi cones. But as demonstrated, it's unnecessary. But you can get a 10-bolt too, I got nothing against those. I just mentioned 9-bolt because they're a little rarer, a little more expensive, and I got the one year they were available with the decent rear disc brakes, and I paid a lot for a lower mileage one and paid a fraction of your budget for rear disc brakes. A 4th gen 10-bolt will have basically the same brakes on it unless you get a 98+ 10-bolt. So a 4th gen rear is just as viable, I just wouldnt be as confident with it with ratios near and beyond 3.73 with a manual trans.

This again? A posi is just GM's branding jargon for a limited slip differential. I say Coke, you say Pepsi - it's the same thing. There's a lot of different ways to do it, most people just aren't exactly sure what "posi" means, so it's easier to just say "posi" instead of saying limited slip differential because for some reason a lot of people think an LSD is somehow "less" than a posi, even though they're essentially the same thing. I think Eaton lays claim to the "posi" label these days, but most people, due to GM's apparently successful marketting during ye days of olde, people think "posi". https://www.thirdgen.org/forums/tech...n-limited.html

Stock 16x8 91-92 wheels (yeah, I think they're ugly too, but they're not as bad as some of the C4 wheels) are cheap. You can get a whole set for less than $100 and fit the same tires you can fit on IROC wheels. Speaking of those, there's a set of C4 wheels on craigslist for $100. 16x8's are cheap. Period. Whining about the cost of them is kind of silly. They cost less than a single tire.

Ideally you'd buy a set of wheels that didnt need spacers, unfortunately that costs a lot of money. If you want affordable wide wheels with shorter sidewalls (which as you well know are an advantage within reason. And since you're gonna try and call me out on it, I'm not talking 26" wheels with a hellaflush setup stretched across it) you're pretty much limited to factory 4th gen F-body and Y-body options. Just so happens factory Corvette wheels are affordable and their larger size offers a good performance advantage. You're right in that the spacers add weight, but if you want 17+ inch wheels with anything wider than a stock tire AND you're on a budget, dealing with spacers is a necessity. So that makes it even more important to seek out a lightweight wheel - which again leads us to C5 Z06 wheels. They're very light, and the spacers add weight, but unless you can afford to order a set of lightweight racing wheels, they're a good option. If you know of any decent lightweight 17+ inch, 9+ inch wide wheel that fits our cars without spacers, feel free to share.

So you want to spend $250+ per tire and you advocate limiting yourself to factory widths? You want to spend big coin on rubber and cheap out on narrow wheels? Do you not see the incongruency here? If I were on a budget I'd much rather invest in some good wide wheels and get some cheap, affordable summer performance tires like some G-Force sports. I'm very impressed with the G-force sports I have on my 16's.

 

Ratech is junk period. I used to think they were a bargain buy until big gear hear (memeber here) pointed out the differences between them and Drivetrain Specialties (DTS) items. DTS items are slighty more in price, but far better in quality. However, they don't make anything for a 9-bolt. I've got a stock 10-bolt and they under my car and they happen to have every part needed to beef one up.

Believe it or not, there is a monster difference between how a posi setup works compared to an LSD. While both do limit slip, the posi is the reverse of most all other LSD's out there, except for Auburn (clutch cone) LSD's. Posi's and Auburns both use springs to push clutch plates together or clutch cones out to engage the carrier wall:



Therefore, the axles are never truly linked to one another and can function more like an open diff than an LSD because its all based on how your clutches work. Unless you have a dedicated racing car that needs the level of tunability afforded by this kind of setup, geared LSD's are the better way to go. Now, an Auburn diff is nice in that you can machine a couple thousandths off the cone to reseat it but your carrier will wear out before the clutch cone needs to be replaced. Auburns aren't known for long life spans or handling lots of power well.

Geared LSD's operate in reverse of this. The axles are always locked together by gears that touch both side gears. The Truetrac & Torsen diff (with the exception of the T2) have no spring to set load, they are forever & always locked and will only allow slip to the extent of the gear ratios of the gear teeth:






You rebuild the diff with the gears installed backward to reduce rolling resistance & change the amount they allow slip, but other than that they are set in stone how the operate. With no load on the diff, if you turn the left wheel forward, the right wheel will turn in reverse at the exact same rate. The axles are locked together, but not like a spool or locker, and allowed only to differential by the gear ratio of the gears in the diff.

The T2 is a combination of a posi & geared LSD to allow for pre-load torque settings to allow the diff to engage & allow slip longer than a straight geared Torsen or Truetrack would:





Where are you getting me whining about them? I've got stock 15x6 wheels on my car right now. Anything that is bigger than that is an improvement. The IROC are the best value for your money (lightweight, fits without mods, and cheap), but you also have limited tire packages to choose from in a 16" wheel. I chose the kind of tire & brakes I wanted first and then looked for a wheel that would fit the tire, brakes & the car without mods. As I've said repeatedly, tires are key to a good performing suspension. You can have every piece of hardware in the world under your car, but if don't have the same kind of tires under the car as your suspension, you're not getting your money's worth out of that hardware.

If you have a DD, having a 26" diameter tire is critical to not getting a ticket for going to fast or slow. Tires under 26" cause the speedo to read faster than what you're driving, so you are actually going slower than the traffic around you. Tires over 26" cause the speed to read slower than what you're going, which means you're driving faster than the traffic around you.

Define lightweight & cheap? Since you asked, I consulted a thread that I linked earlier (and since SLP's are now the same price as these, I think my wheels are going to change so that I can get that next size larger tire as well) to get some good info:

http://www.summitracing.com/parts/CRR-617934P/

17x9 Cragar SS wheels with 5.5" BS and the 5x4.75 bolt pattern. The only wheel that Summit lists that is the biggest 17" wheel you can fit to our cars according to the mentioned thread. $250 per wheel. If cost is an issue, I suggest patience and saving up for the wheels. I'm going to be waiting a year for these puppies and another year for the tires to go on them (assuming my pay level is static forever and I never pay off my student loans). I'd much rather wait and buy the parts I want than buy what I can afford right now.

Like I said before, I have 15x6 wheels and can't find a set of 16x8 IROC anywhere around here. When I was looking for wheels, SLP had the ZR1's in a plain jane finish that was about $500 for all 4 wheels. They now only sell the chromed version, which is the same price as the Cragar wheel I listed. So for the same type tire & price, I can get another 8" overall of contact patch on the pavement. There's tons of options to work with in a 17" wheel & 26" tire and thats why I'm sticking with a 17" wheel.

 

Ratech sells junk? I'm talking about buying shims, bearings, gaskets, pinion spacers, differential gear bolts, etc. If you're afraid to use their junk gaskets and shims then I guess that's your call...

All you're talking about is different ways to make an limited slip differential. Still doesn't change the fact that a posi is just GM's old school name for a limited slip differential.

http://www.ls1.com/forums/f8/posi-vs-lsd-13054/

https://www.thirdgen.org/forums/tran...d-vs-posi.html

And here is big gear head saying exactly what Im telling you:

https://www.thirdgen.org/forums/post...050-post3.html

16 inch 91-92 wheels are lightweight (at least they weight as much as IROC wheels.), fit without mods, and are even cheaper than IROC wheels. If you can't afford IROC's easily, a set of 91-92 16 inch wheels are a functionally equivalent alternative. That's all Im saying. I'd stay if you're going to spend that kind of money on wheels you should get a wider set than factory 16's. But that's your call.

 

Arg… I wrote a longer response and the web page crashed when I tried to post it. Short version- I disagree with or don’t feel that a lot of what’s posted here is helpful for the original question.

First, yes, these cars (and most cars) understeer stock, it’s a fact of life, that is safer for most drivers on the road. It’s also easy to fix, heck, if everything is right on the car just a non-factory alignment could take it from understeer to oversteer.

Second, a lot of the info posted is either parroting back what people have read and haven’t experimented with- yea, people like X, but that doesn’t mean it answers the question. The problem is that you’re not asking what setup works best for autox or rr- that is typically not the best setup for handling overall but one that fits within some specific rules which results in some compromises that you wouldn’t want to make normally. I also don’t think that you’re looking for the best handling 3rd gen, you’re looking for a killer handling street setup, which is different.

First worn out/loose parts, linkages… need to be fixed

Second, to make the rest of what you’re going to be doing work best you need to stiffen the chassis. Some good “outside” SFC will get you most of the way there, make sure that they are positioned so they can be stitched to the rockers, that adds a lot of rigidity. Skip the inside SFC, they add more weight than stiffness, especially once you have traditional ones installed. If you feel you need more stiffness there then add diagonal braces from the outside bars tying the tranny mount end of the subframe in, or if you’re going to go more serious, tie in a roll bar/cage (that will add much more stiffness, also get in the way on the street). Wonderbar is simple, quick and works, I’m not sure strut tower braces do much in this kind of application (many of the designs are marginal and add more weight than stiffness)

Oh, you’ll see a trend here- weight is the enemy. Put enough tire on a light enough car and it could flex and have a crappy suspension and still handle awesome (look at the ford cobras, small light chassis with a lot of tire and engine=fast).

Brakes- massive brakes are nice- on a road course. Big brakes don’t buy you stopping power, that is brakepad compound, balance…. All big brakes buy you is repeatable stopping power. They prevent them from overheating and fading. Something that you will honestly never use on the street (If you drive so you do you’ll probably kill someone), and generally an AutoX run won’t tax them very badly either. Big brakes are heavy, cause you to use bigger, heavier wheels… all of which cost you unnecessary money. If you ever get serious into road racing you can upgrade brakes, wheels, tires… to something more appropriate then when you know what you need. In the meantime get a good performance pad and if you’re worried about fade run some brake ducts. BTW, for street use aluminum factory drums work well and are lighter/have less drag and are a better design then the factory disks. If you want to run close to factory disk sizes in the rear swap some LT1 rear disks on it, they’re a better, more reliable design..

Tires- good tires are important, but balance that with your intended use. Super sticky track gumballs are great- at the track, suck on the street where conditions aren’t perfect (even warm weather Z rated tires can suck on a cool day, throw in a little rain…). Figure out what will work for what you want it to do. Tires will decide the rims since available sizing tends to be a limiting factor.

Wheels- go as small diameter as you can get an appropriate tire for. Going from 15 to 16” factory firebird rims, same style could mean almost 15-20# difference PER wheel/tire. If there were good, serious performance 15” street tires available that’s what I would be running. PERIOD. There is some good 15 and 16” race rubber out there, but if that’s appropriate then you might need bigger brakes… otherwise current street tire availability will cause you to make some unpleasant compromises here, shop around, I’ve seen some good stuff show up for cheap recently, some cheap, light circle track rims and street radials intended for classic muscle, but the last time I _really_ looked I ended up buying some Z06 17x9.5 and 18x10.5’s because I got them new with appropriate tires for less than $1000. I don’t like the combination but it was cheap and works. It’s also heavier than it needs to be and the short sidewalls compromise ride quality (the whole “tall sidewalls hurt response” thing is complete crap, put a set of 26” tall race tires on 15” rims on the car and go for a spin and you’ll never have that reaction again, OTOH, put a set of tall sidewall street radials on an all-out race suspension car and drive it on the street, you’ll find that it actually works quite well and will have a surprisingly civilized ride)

Try keep the wheel width as wide as you can fit without hitting things and on the wide side for the tires that you’re running. It will better control the tread and keep it in contact with the road. A wide tire on a narrow rim sort of works at the dragstrip, it doesn’t work in the corners.

Springs- GC weight jacks are neat toys. Totally unnecessary on a street car, don’t really give you anything over a spring with the correct ride height/rate and put the adjustment in the wrong place. If you insist on adjustable then get some circle track style weight jacks and cut and weld the stock spring pockets for them. The only real justification for going this far is if you’re going to take the time to set corner weights, and those will change every time you fill the tank, have a passenger, carry a load…

Otherwise I’m a big fan of specific rate springs- progressive springs tend to be numb (soft) around neutral, so in transient maneuvers you tend to have less control then you’d like. Generally, something in the 700-1000# F and 175-225# R range works pretty well. I don’t know where the straight line comments about eibachs come from, but the fronts are good, I don’t like the progressive rate rears I run them with a set of cut WS6 rears in my formula, in my ’83 TA I really liked the cut stock WS6 F & R (890# front/210# rear). Cut Moog replacements, eibachs fronts, GW… all are fine and in that range. I’ve tried/driven probably 2 dozen other setups and pretty much anything in that range works, and you can fine tune with sway bars and bushings. BTW, if you lower your PHR or do some other mods that will lower your rear roll center you’ll need stiffer rear springs or sway bars.

Sway bars- Skip the great big solid aftermarket bars. People started using those to take advantage of autox rules. I have the same problem there as I do with progressive rate springs- big bars compensate for not enough spring rate so you can run a softer rate in a straight line to soak up bumps, yea, that’s OK but I feel that you get too much weight transfer f/r in braking and acceleration, upsetting the car. I’d rather run slightly stiffer springs and softer sway bars. My favorite combination is factory 32mm/22mm solid bars (I’d love to try a hollow 34mm front but haven’t gotten my hands on one yet. I have a couple of sets of the typical 36mm/24mm hollow WS6/IROC/Z28… bars and they tend to be a little stiff when I get the spring rates where I want them. FWIW, I usually end up with a little too much rear spring by the time I get the ride height down to where I want it and can usually fine tune by running poly front bushigns and rubber rear on the sway bars.

Shocks/struts- OK, the rest of what I’ve suggested so far has favored the cheap solution… Spend your money here. Koni Yellows are the deal. There are more expensive custom solutions, but the koni’s get it done with the off the shelf setup. Some of the mid-price “performance” shocks/struts are OK, but put them next to some Konis they don’t compare. FWIW, the rears are pretty stiff- for lower speed stuff you may want to consider adapting the softer fox chassis rear shocks, they are a little softer (as the speed you push the suspension at goes up, these cars tend to like a stiffer rear).

Poly bushings work fine in the front LCA’s, derlin work better, but are more harsh. Rear bushings are a touchy deal. Poly work if you keep them well lubed, but can be a problem if you don’t. Bearings are a good solution from a performance standpoint, but they aren’t great in a street application (harsh and don’t tolerate dirt well). There are covers that work, I like taking poly tie rod boots, modify them with a carbide cutter and fill them with grease and assemble them on either side of the joint. I’ve done rubber, poly and assorted bearings- they all work if you account for their differences in tuning and maintenance.

Other rear suspension mods- PHR will make the biggest, easy change, the stock one flexes and can cause the rear to jump around making the car want to loop at the wrong time. A Watts link is probably overkill, and I’d bet that 99.99% of people couldn’t tell the difference, or at least most of the rest of the suspension will make a MUCH bigger difference. LCA relo brackets- great for a drag car on slicks or other, big soft tires, not as good with a stiff tire, and actually hurt some in a cornering situation (optimum position for handling is with the LCA flat or with the front slightly lower than the back). Decoupled TA- yes/no/maybe? They work, there is an advantage to them- better acceleration and braking, no compromises WRT to handling but they’re complicated, a hassle, and just hard to implement well/without adding a lot of weight. I’d seriously consider one for an all-out effort, but wouldn’t bother otherwise. Boxed stock parts work well, tubular parts _might_ save a little weight, depending on your skills.

 

The stuff needed to rebuild a 9 bolt is available, you just have to do some digging. I've used ford 8.8 shims to tighten up the posi, the bearings are standard parts that can be bought at a bearing supply or standard parts house..., and the rear is actually a great design, stronger than a 10 bolt, proper bearing retainers/no c-clips... well, I've have a stack of hard parts sitting around for it in the garage.

OTOH, I've mangled one of them as badly as all the 10 bolts that I've broken...

 

OMG 83, you wrote out a ton of VERY good info that i just quickly scanned, and will have to reread when im not exhausted. Yoi hit the nail on the head, i am looking for a killer street handling car, not an all out race car like what other people thought.
Thanks again.

 

Very cool thread with great info, and Matt, my car had the same issue with the awful understeer. I ended up addressing that with a better alignment. Here's a thread I started about a year ago.

https://www.thirdgen.org/forums/susp...ndersteer.html

 

FYI, anyone interested in getting Koni yellow rear shocks (30-1265 S) at a great price.. PM me.. i got mine from an Ebay seller who has his own shop.. price was $89.99 each with only $9 shipping for the pair.. got mine in 3 days.. normally the cheapest place i have found sells them for $127 each..

 

Amen to that one, know that one first hand. Had a lsd in my 89 and took a 90* to the right on a rainy day. Me being used to my 65 gmc that had a posi, took that corner and started to accelerate with my 89 camaro rs. Big mistake, my luck was that no one was coming the other way, or I wouldn't be writing this two you right now.

 

Now here is a ton of real world useful info.

 

Is this what people mean when referring to Koni yellows?

http://www.summitracing.com/parts/KON-30-1265SPT/

and

http://www.summitracing.com/parts/KON-8741-1030SPT/


Those rears are bearable on price but still expensive... but 272 per shock for the front, no way that I could see spending 544 dollars for two front shocks...

Surely there is something better in price that performs well for the average street driver that might go on a road coarse for fun occasionally?

 

I think Tokicos are a good budget friendly alternative.

Are they as good? Probably not. But does the increase performance justifiyto the cost difference? Probably not for most 'street' cars.

 

That's them. Honestly they are worth the money. They are also warranted for life. So when they wear out, just send them back to Koni for a rebuild.

 

I dunno... I would need to ride in two identical cars (same suspension components) except one with the konis and one with some affordable ones to see what I think before spending that much money on them lol.

I can get a set of good performance shocks recommend by a local performance parts shop for like 80 dollars per shock. I forget what brand they said they were but this is one of those things where I Just can't see there being that big of a difference between what people consider "average" and what people consider "the best".

It's like TV's, Vizio is a low cost average quality TV, and Sony is considered high end usually. If you look at them side by side the differences are marginal and looking at them separately you'll never realize the difference, so why spend the extra few hundred dollars on a Sony.

I suspect a lot of car parts are the same way, and guessing just like Sony, a lot of "the best" are simply name hype with some marginal improvements.

 

I agree with your assesment that the best is often marginal improvemetns, but I would question thoe $80 shocks, if we are talking front sturts any way.

 

That's what everyone says until they get the Konis. Then it becomes immediately obvious that they are worth it. Just read the reviews on here. For me the Konis improved the ride quality just as much as the performance and feel improvements. Car rides great now, instead of like a bucket of bricks.

 

What were they replacing with the Konis?

 

In my case they were replacing 1000 mile Monroe Sena-junks. I believe Twin Turbo has run just about every strut available for these cars. I would ask his opinion if I were you.

 

I'm searching now.

I am not trying to say konis are not good. I know that when replacing a used strut they will obviously feel better. There is also the placebo effect, where we convince ourselves we see an improvement.

I would like to hear from someone who had near new Tokicos or Bilstiens and replaced them with Konis, and how much 'improvement' they saw.

 

A 1000 mile strut is hardly used.

Like I said, talk to Twin_Turbo, he has tried them all.

 

Yes, but a Monroe parts store strut is probably not as good as a Tokico, either.

Anyway, we are getting off topic here.

 

Well I finally got around to ordering a bunch of parts for the car. It has taken a bit of a different turn than the "best possible handling" to more of a "way better than stock" handling. Since we have had snow here already and the streets are covered with salt, the car is officially off the road and parts are about to be installed. Here is the suspension/handling parts I have decided on.

Del a lum bushings
Poly end links and mounts for the front sway bar (rear already has them)
Eibach pro kit
Tokico Illumina Shocks
LS1 Brakes
J&M Strut Mounts
UMI SFC
All new steering components
"Performance" alignment.

That should totally transform the car.

I know how good the Konis are, but read a TON of reviews and between the price being so high (Im also doing a t56 swap this winter along with a FULL exhaust so I had to cut costs somewhere and I want a new DD) and people said they are pretty much a track specific shock. I DD this car in the summer, I went with the cheaper but still very good quality Tokicos.

 

Sounds like you will be very happy with your parts selection.

 

Koni yellows are the single best upgrade I ever made to my car after my T56. They're amazing, and I'll never have to replace them.

You could probably get parto f the way there with some Tokicos or KYB's, but there's a reason Koni has so much cred around here. KYB and Tokicos are just "an okay budget performance" shock. Konis are the best you're going to get without getting something custom tailored to your car by an aftermarket company like Penske.

That said the Koni's arent the best for drag racing, but for handling Koni's ARE the budget shock with marginal returns beyond them. You want racing shocks, and you will pay at least a grand for custom made, custom-valved shocks from a racing shock company. You want the cheap alternative - Koni yellows.

BTW I got mine used. Given how durable and well warranteed Koni's are, I would have no qualms about running used Konis, so just keep an eye out for some.


That said I dont think you'll be unhappy with the Tokicos, I was gonna go that route too until I found my Koni's used.

 

if you never get to compare them side by side, you'll probably be OK with the tokico's on the street. If you do you'll be disappointed that you didn't spring for the konis (they are that good, I bought one of my 3rd gens from a local competitive autocrosser and at the time he had koni's on the front and tokico's in the back, the rear konis came with the car. I couldn't believe the difference just swapping the rear ones made).

Otherwise good combination, the only thing I would add would be an aftermarket PHR, that's what I've always noticed first flexing on the rear suspensions of these things (the car will jump sideways on a hard shift/big tires will rub in a hard turn)

 

Are we talking Koni reds or yellows.

 

yellows, the adjustable kind

 

Thanks i got an adj phb already on the car.