radar502

I researched the handling set up on the C-4 for 3-mounts and this is what I cane up with .Put the biggest stuff in the front you can find the back is the problem and is the sway bar if too stiff will not let the back of the car move and bite .. The rear has to move to work right,, fine line too soft too stiff ..This is what I came up with all NOS parts..and love it can run turn for turn with any stock C-5 C-6 can't pass don't have the power I can push them in the turns..Track vett sunday vett club vett just very good alaround ride..Rides a little stiff..It's a 86 style Z-51 set up 1 1/8 F.sway bar Front spring FHA F/RATE 93.1 Rear Spring NYC R/RATE 57.2 .. No poly on rear bar will not let it work right. Had Biletein rebuild the shocks to mach Sup. The alignment a cross between road race and street works great for what I do.. GM knew what they wer doing when they build this C-4 just have to put right parts in right place..This is not my set up I didn't come up with it ..Guys that have raced these for years cane up with it.. I just called and asked lot's how to and what to do stuff.. It's not fancy stuff I can go into a turn at any speed if the tires will hold I come out on other side.. What I like best it stays were I point it, stays in track... I put lot's into this just trying to help good luck..

jaa1992

Let me get this straight - you were able to use a z51 spring from an 84 on the front? or just an FHA spring from an 88 and up?
so 1 1/8" is a 28.5/28.6mm bar? what year and suspension was that off?

What does this mean "Had Biletein rebuild the shocks to mach Sup."

I realize you typed it out fast, but some clarifications would help those of us searching for a decent track setup without going to coilovers.

TIA!

USAsOnlyWay

This sounds similar to the setup I am going to run, obviously haven't run it yet and also have pst bushings all around.

Sway: 30/26
Spring: BMB (84-87) or (88+) FHB/NYU
Rates: 102 or 115.5 / 57.2


There was never a 28 or 28.5mm bar offered by GM...
http://www.corvetteactioncenter.com/...usp_chart.html

Cavi

Just fyi the vbp sport springs are the same rates as the z07. And ecklers sells a set that are the same rates for the z51. But that fit the latter models. Keep in mind the c4 should run b stock by scca rules and if the z51 was not available in your year you cannot use those rates only the z07 rates

radar502

84 Z-51 stuff will not fit on the 96 ..The 84 Z-51 Front Spring is around Rate-105.0 and the rear is around Rate- 100.5( Too Stiff for me ) I don't have the numbers in front of me and it's been a year I was looking and talking to people The FHA spring is off the earlest that will work on the 96 and the rear also ..The bars are VBP 1 1/8 Front and the rear is 26mm S. no poly in the rear has to be new rubber bush and all in good shape and not worn can't be 10 year old stuff and be right on for it to work right ..Lot's of people want to put poly in the rear and bind the rear up it has to move with the road ..The big spring in the rear helps with the swy bar but has flex in it stiff but moves.. My springs were NOS in the box ..What I came up with is the same set up as in the 86 Z-51 set up ..The 95 ZO-7 has the same bars but the springs are the same rate as 86 Z-51 stuff ..Go the the spring chart an look at the 86 Z-51 Corvette will see it.. If using used springs have to know what year vett all are not the same may have the same letters but different rate .Need the year and the chart to know what you got ..Not easy I worked on this for days..This combo handles with any stock vett my friend has a older ZO-6 cruve to cruve I'm right there..Need more info be glad to help . Spazianimike@aim.com we can talk... Hope this helps...

radar502

Forgot Biletein will rebuild old shocks .You have to tell them what you got and how you going to ues the vett ...There on line look them up...Like I said it's been a year I have the info somewere ..Not hard to do.. The price not too bad for the rebuild... and work great..it's a combo thing can't just but parts on and have a good handleing ride have to work at it ..The parts have to work together..Lot's people just give me the big stuff and think I got it or lesion to the young sales guy..NOT THE DEAL ...

radar502

I went back and loked at the chart..If you can olny go stock what 92 ZO-7 set up looks like a good one ..The alinement is the key with the C-4 may have to try two or three times to find witch one it likes .Mine gets a little off from what it likes and will not handle as good have to keep it right took me three times to find the right one for the Sup... you know when you get it ..Drives very good half a turn here and there dig deal with the C-4..

radar502

I went back and looked at the chart I was off ..It'd been a year I thinking that 115.5 is very big and is ok ..Guys told me can't go too big in front .You should have a good set up.... a 28mm ???? I went in in. with the bar in front and mm in the back that's how VBP has them listed ..Just read what i said about the rear it works and good luck...

Cavi

yeah, the z51 is 115 while the z07 is 93, the vbp sport is also 93, and since the OEM springs are no longer available, most clubs should be okay with using the vbp as the rates are the same as the z07 so there really would be no performance advantage. Personally this is the setup I will be using I will be buying in the next month. I would reccomend doing the front and rear matching models. In other words if you go with the vbp in the rear go with their mathing in the front also. I would also reccomend waiting on the shock rebuild until you install the springs, keep in mind with a harder spring you might actually want a more compliant shock with a slightly different rebound setting.

jaa1992

Luckily mine came with the Z07 option, so I have those springs and bars. I'm just not having good results with the revalved bilstien shocks I purchased several years ago. The main issue is the most I can get is 0, thats right zero front camber. I've got the adjustable lower bushings to install this winter and that should get me a little camber, I'd love -3 but anything around -2 is workable. Of course I'll need to learn to drive the car all over again

I was thinking a heavier front spring might be helpful. I can go aftermarket without changing classes, but coilovers are not an option because it starts throwing me in unlimimited classes. They are only governed by adjusted hp/wt formulas and then the cost is thru the roof to be competitive.

USAsOnlyWay

Ah I see, I thought you said all your stuff was GM. I see now, springs are GM, front sway is VBP, got it.

Yeah, I think the setup will be good. I have custom valved bilsteins for spring rates that are pretty similar (a little stiffer in the rear.) I ran it last year on stock springs as that was all I had and didn't have time to change it. It didn't do too bad, but it needed more!

radar502

We had play day at the track this weekend and was runing with a 2005 ZO-6 all stock get in the strate he would leave me by 3-4 cars about medway in the trun I was right there and stayed untill we hit the strate he would pull away..We way I see it he was runing 120mph I was doing 105mph he had to slow down I just powered through it .Have to have VERY GOOD brakes to set it in the turn .If when going into turn ..The C-4 with the twist sometimes get it a little off I just hard on brake jerk it back and hit gas ..If you got stock stuff and got power drive hard you better be up on the wheel and brake steer stab to get it to work for you I was told by people who know " Can't go too big in front bars springs if the back is bound up the C-4 will not turn and will try to go home if you want it to or not.. You need all the ajustment you can get in the thing it's a big deal in a C-4.. Stock have to be right it all has to work togeather .. 26mm bar in the back big spring will come in when the bar gives out and works with bar to keep keep tire on ground but will has fex to let the tires move with road ...I was just lucky to hit this one without too many trys..I have parts Iv'ed tryed and did not work have three sets shocks poly bushing all over the place alinement numbers to fill a book are in a book ..The place to start is big in front and small bar and big spring in back and lot's adj. it to it's right and show it who's boss got to have good brakes that's for the OOP's thing hit brake start over change BVDs.... The ZO-7 a good set up the shocks not if not already take that button off and get a good set without that button thing useless those shocks useless ..Get some good shocks that go with what you have .. Make way better ride....No FX...Good luck

Cavi

Jaa1992
Truth be told, if you could get -1 you will probably be estatic, I personally feel that -3 is overkill for a c4

Toy90

I got -2 on the left side and -2.3 on the right with no shims and I don't even have offset bushings. The wheels tucked up under the fenders quite a bit and it looks mean. I didn't do it for looks but for road courses. I can tell you more is better because the tires are still wearing on the outside couple inches and the tires need to be flipped on the wheels. With this setup using 1990 Z51 springs that are lowered and 32/26 sway bars/camber brace/Nitto NT01 tires I can run a 2:43 at Road America with stock pads and brake cooling ducts. I brake very early because I don't trust them and never upgraded. I know I could be in the 2:3X's with good brakes. As it is now I am passing cars with over 100hp on me just because I can take corners that much faster with confidence. People with faster cars would come up to me and ask what they heck I did to my car and for the most part it's a stock LT4. Now I'm going to sell the car and will have the sways/camber brace for sale if you want them after I get them pulled in the next week.

Cavi

let me know how much on the parts, I might be interested

dan_t

I didn't read the whole thread - but let me give my 2cents on the springs.. IMO what made the 84 Z51 the stiffest car was the Spring and Shock COMBO.....

I replaced my 85 NON Z51 springs with 84 Z51 and was very supprised at the little difference they made - other than making my shocks feel like they weren't able to compliment the springs.

I have a solid 30mm front bar and stock rear - I already cornered pretty flat but wanted to control Accell/Decell motions a little better.