corvette90

Hi all

have a question about spring rate/spring length/ ride height

it seems to be a well accepted setup on the C4 with 400lbs/10" springs front and 275lbs/10" springs rear, ZR1 425lbs/10" front

friend of mine runs the first setup on his C4, the threaded collar in the front is about in the middle, the collar back in the upper quarter of the threaded sleeve, and the car still sits rather a bit low

i want to upgrade to a coilover setup, mainly to restore (leaf springs are 25 years now) and of course, upgrade ride quality and level the car.

my question is, should i try 12" springs in the rear, i want a near stock, maybe a bit lower ride height and still have room for adjustments..

maybe its just a brain bug, but i like things that can be adjusted to hoover around a center..

thank you

WVZR-1

The branding of the coil-over shock will generally require a specific spring height. I'd suggest not deviating from that. Rates for sure can vary widely and I don't believe the rates you mention could be considered "gospel". Rates would be very dependent on the use of the car. A coupe or a 'vert?

The length of the threaded sleeve and the placement of the snap-ring locating it is likely what is responsible for the "visual" on your friends car if it's done with modified Bilstein product. Some coil-over product is supplied with shocks already threaded.

corvette90

Hi Dave!

you are right, modified bilsteins, the thread sleeve sits about 1" above the lower shock end.

car is a coupe!

im also with you, that the rates are tested and proven to work, so i wont alter that.

i also want to use my Bilsteins, as i haven them overhauled a time ago...and would overhaul them again if necessary

thank you!

WVZR-1

It's been a while for sure!! Reinhold

How go things?

I have a set of these that are very low miles and I don't recall the spring rates but I've considered selling them recently and likely just doing my FX3 shocks for the same package. If these might interest you send me an email and I'll check the spring rates.

I believe maybe you'd just require the sleeves and hardware so maybe you wouldn't use the typical branding used here. You might even have a wider variety of options than we do. I believe you can do your own "grooving" for the sleeve snap-ring, I'd think the proper I.D. sleeve is likely available also. You could likely assemble the needed parts locally and not be interested in my package.

If you need any information drop me an email!

aDigitalPhantom

I changed the rear spring mounting and use 8" springs, but my car also sits low. I'm useing 450lbs/10" springs front and ~350lbs/8" springs rear. The rear springs are too stiff and I'm planing on changing them to something around 300lbs/8". The front springs are great IMO.

corvette90

i´ve read and heard from someone who had also installed rather stiff springs in the rear, the car begins to hop/bounce, 275 in the rear should be a good setup for street driving...

i plan using 425 in front like the ZR1, as my engine is heavier than stock..

regards

WVZR-1

There's considerable calculations required when determining "spring heights" It's not as simple as "experimentation" which it seems you may have attempted. The 10" height is a reasonable calculation based on the shock stroke of the Bilstein OE package. To achieve ride/handling or any compromise of the two requires an installed height that utilizes the total stroke of the shock. Not being familiar with your install it's likely you've got something "compromised". There's a multitude of coil-over calculations out there that deal with very accurate calculations and explanations as to how to measure.

It would seem that to use an 8" coil height you would need some "specialty" shocks. You didn't mention what you've got so if you've other than OE maybe the set-up is correct with an 8" spring height. Do you have maybe QA1 or an older Carrera package maybe?

When we did our first coil-overs there wasn't the luxury of the Internet and research was much more difficult. It was often a "for hire" project and you used what was the result of someone else's calculations. It wasn't for a C4 Corvette.

aDigitalPhantom

WVZR-1 other then the rear shock mounts this is the page I used, and have said it before. http://www.ndneyes.com/page5.html

The lower mounts, I'm using these. It was not adjusted when I took this picture.


PS
It corners far better then it did with the mono-leaf. I have not hooked up the front sway-bar, and IMO it was better before re-connecting the rear.

corvette90

that looks an interesting construction and may explain, why you are lower a good bit..the center of the shock mount NOW seems to be about 1" lower than the STOCK mount position..also, your spring adjuster is at the bottom

you also changed the axis of possible shock movements...transversal now vs longitudinal stock...