Cavi

so next on my list is the upgrade from base springs to Z07 springs. Who has had both? Is the Z0 going to be way harsher ride? I know I need them for autox but still I am loving how the car feels right now.

PLRX

Cavi, if you scroll down you will find this Z07 monospring stuff already discussed. You will not need to search it.

Members use them, swap them, soft shocks, HD shocks, big sway bars etc. All of it.

Cavi

Okay I have a 94 with base suspension, so I have 73.2 up front and 39.9 in the back. I plan on doing autox and want to firm it up a bit for this. the Z07 uses 90.1 in front and 57.2 in the rear.
Someone offered to sell me a set from the base of a 91 which uses 93 up front and the same as I have in the rear. This would be basically the same in the front as the z07 but the rear would still be stock and softer. I am not sure this is really good to have or not. Anyone here try this type of setup?
i am also considering the vbp sport springs, the only thing that is holding me back is that going with the 93 up front would be deffinitly be less $ so I could do that now vs waiting.
Ideas? By the way, I did buy a set of larger sway bars a 30 up front, though they are not on the car yet.

leesvet

I'd be more concerned with the rear myself...
the fronts matter, but its the rear where the majority of the body roll happens and where traction is lost under power and in corners under power, so thats where you want a fast spring rate to get the tire back on the road asap when there is a suspension compression. Of course that means its gonna be what most folks call "stiffer" or harsher, and it IS, but you want less compression of the drive wheel suspenion so they are firmly on the road to transmit power into motion. A wheel thats rebounding and reacting to every little dimple in the road can;t do that.

There is an adjustable available for some $$$ and there are lots of places that sell springs as singles. Get a step up for the front when you can, but I'd focus on the rear for more control. You'll hate the car if you go too stiff/fast on the front and drive it on the street. Besides, the front is way more hassle to swap springs out. Rears can be done in 30 minutes with a jack. Be sure to have some shims because no 2 springs are shimmed the same way. This also helps lower the frame by a few mm if done correctly.

There is also the coil-over option, but being a purest I won't go there no matter how convenient it is to adjust or service. IHHO the transverse monospring also helps keep the car level and resist body roll with spring tension against the lateral motion, assisting the roll bars. Like roll bars with the opposite pre-tension. With coil overs there is no continuity to the lateral suspension action. The body could sit anyway it wanted to. If one spring got weak, that corner droops. With the monospring that end of the car is going to be the same unless a spring breaks and its over at that point anyway.

Cavi

So, other than the different springs what else was different on the Z07 package? I am looking mainly at 1994 if it matters

mashinter

bigger sta bars
stiffer lower control arm bushings
larger front brakes
FX3 shocks
275/40 17 tires all around

93Z07

The 93 Z07 came with J55 13" brakes, sport seats, adjustable suspension, solid thicker anti-sway bars, stiffer springs and P275/40ZR17 tires all the way around.

Cavi

thanks!

Alan777

I thought non- z07 cars came with 275's the whole way around too.

And did all Z07's come with sport seats?

c4cruiser

Starting in '93, base suspension cars got 255/45-17 tires on 8.5" wheels in front and 285/40-17 tires on 9.5" wheels in back. The 89-92 cars had 275/40-17 tires on 9.5" wheels regardless of suspension.

Cavi

okay, my 1994 coupe came with the base suspension. I am going to use it as a DD and for autox. In order to remain in the B stock class I need to run spring rates that were available in my year. My base setup has 73 front and 39 rear. The Z07 had 90 front and 57 rear. I managed to find a 93 front and a 57 rear. I know the 93 is 3 over the 90 that would have been on the z07, but I figure it is close enough.
I will also be running the heavy front and rear sway bars. For shocks I will run QA shocks. All this should be okay with my club and me remaining in stock class.
A couple of questions, will the stiffer springs make my car sit higher? VBP sells both a 10 inch bolt and a 12 inch, I am guessing the 12 inch would drop the height of the car. I do not really want to drop the height, but will I need to in order to maintain the current height after I swap the springs?
Last, I also want to know if there is any difference in shape of the springs from the 90 that is the correct for the z07 in my year and the 93 that comes on other years?

leesvet

No.

The stiffer the spring the less ARC it has...so the body sits lower on the chassis.
The softer the monospring the more ARC so its tends to lift the body up off the chassis. You can also get some adjustment by moving the shims from over to under the spring. This is only a few mm but it makes a difference.
My 1984 419 lb rear is almost flat (maybe 1-2" arc) while the stock 240lb spring had a good 6" of arc.
The 499 lb rear IS flat and like a steel beam across the rear end..not much makes it move. Hell, I can jump up and down on my 419 lb and not make it flex while laying on the floor...and I'm 230 lbs of lard hopping on the thing...its stiff. I cannot imagine how harsh the 499 would be on a DD...mines pretty near miserable.

Cavi

What are you running on the front of your with the 419 in the rear?

leesvet

Front is the stock HD z51 for that yr...since its more prone to have washout from steering skidding, the rebound is not as important as the shock and the solid roll bars. Its the *** end that wants to roll and shift weight to the other side suddenly causing the *** end to break away and go elsewhere.....so, preventing ***-roll, by a good firm plant on the ground solves this issue. Rear will try to roll out if you oversteer. Thats where you can use the flat stiff spring to help keep it level and stable even under hardest of cornering where it wants to break loose so bad that you can hear it beg....just hold it an make it take the corner. It WILL>.

I like keeping that rear glued to the road and allow the front to wander a little. If ever out of shape the front can be so easily corrected and planted in a course that YOU like. The car will follow well.

PLRX

http://forums.corvetteforum.com/c4-g...e-springs.html

http://forums.corvetteforum.com/c4-t...-question.html

http://forums.corvetteforum.com/c4-g...z07-specs.html

JrRifleCoach

Who's gonna check your springs unless you've gone and told everyone?!?
Unless Roger Johnson is in your class, then springs aren't your only problem.

Aurora40

All versions of suspension have the same target ride-height according to the FSM.

The softer springs have more arc because they are softer. The weight of the car will compress them more until the spring has enough compression to offset the weight.

dizwiz24

man, if you've ever raced with the akron sports car club, someone would notice.

Ive never heard more 'bickering' and 'complaints' on suspected 'illegal mods' when one member gets beat by another member.

Alan777

Anyone confirm what spring codes are on a 91' Z07? I'm seeing FHB front and NYU rear.

OP, Assuming I am a Z07 car the ride isn't harsh at all. Granted I've got adjustible, but even on sport/perf it's nice on the highway. The only irritating thing is when the road is REALLY bumpy the car rocks back and forth. I don't find it that much worse (as far as ride quality goes) than my base 88' was.

dizwiz24

this is the first ive ever heard of someone not wanting coil-overs vs. transverse leaf spring.

Most race courses are flat, and in good shape. The whole course usually has with both halves of the lane level.

But consider in street driving this scenario:

Buddy (on his cbr600) and I are messing around on some country roads. Farm fields everywhere.

There is a 90 degree turn left with a dip right before it. This slight dip is only on the right half of my lane of travel. The way that dip is set up effectively creates an 'off-camber' situation going into this turn.

This dip should have only affected the right side of my car, but thanks to transverse springs, now telegraphs itself to the left side of the car.

Yes, I realize that the right side of my car is generating 85% of the turning in a hard left turn, but I still want that 15% from the left side.

I took this same turn in my bmw 330i, a few weeks later, and felt much more planted and stable due to its truly independant suspension.

In fact, that bmw 330i feels much more 'buttoned down' on a slightly rough, patched rural road at extra-legal speeds than my corvette.

The corvette bounces all over the place. Bilstein z51 shocks helped a bunch, but if I were to go to stiffer springs, I think Id be bouncing more.

So my thought is:

racetrack: a well setup transverse spring setup is fine
street: cant beat coil-overs - for situations like I describe. .