Stock leaf springs preload when lowered

[racingvette]

Originally Posted by zteve06

Thanks RV, maybe my springs are just old, but at one inch, there is very little pressure on the springs, and lowered all the way on aftermarket bolts, the spring is so loose I can push it up with my hand with the car on the ground.
I agree about the shocks, it seems you can't lower the car without affecting the suspension's performance.
Zteve06

The distraction is your comment that spring is loose and can be pushed up by simple hand movement.

As mentioned lowering the car only like a inch is not going to have the effect your having as the natural state of spring shown below would take a lot more load taken off the spring by the length/distance of the 2 end bolts.

As I stated my 2001 C5 has been lowered since almost new and it takes a floor jack pushing spring upward to even relax spring off the head of end bolts.

[racingvette]

Fast Bump ?
Jack the car up, leave it there for couple hours and then put car back down and it takes some time before car height even settles so I see no fast bump

In fact if you look at the spring ( examples below) the ark of natural shape of spring would take a lot more loading of spring to even get it close to being totally horizontal

I think many of use who have been racing C5s or C6s for decades know a lot more then your letting on as "peeps" not having a clue.

If shims were installed between the top of spring and cradle I think would only cause rear end to raise up again UNLESS the spring in your case is cracked or reduced tension due to heat.

No way to see if there is any crack on top as shown below

Most wheel hop on C5/C6 is the left half shaft winding up and then unloading like a spring and why GM starting with ZR1 uses larger diameter half shaft on left then right side has

Also consider both swaybars as stocks are bit to small in diameter where 3rd party ones for racing force more pressure into tire patch and keep other side from lifting

[XFordGuy]

I was trying to let this go, but I'll take another stab.

When you assemble the rear end control arm assembly, you can put everything back together without installing the spring. This includes all the other limiting factors such as the shock.

When you install the spring with the suspension fully unloaded, you have to compress the spring to get the stock ride height adjuster to reach the spring. In theory, you could put a bolt there that is so long that you didn't need to compress it to reach when unloaded. I believe this is the "preload" that is being referred to.

But once you sit it on the ground, the spring is going to be under load despite the bolt length. You can shift the weight around using the height adjusters, but you can't remove it.

[zteve06]

Look, this isnt all theory, I have torn hell down my favorite twisty with the rear in different ride heights, and i have felt the difference. In a turn, under throttle, with the car lowered, the rear tires take longer to regrip after a bump, than they do at stock ride height. The shock travel is certainly an issue, but the shock pushes from the top, and the leaf spring pulls from below. Also, the spring has quite a bit of leverage on the cradle, as opposed to the shocks which fight leverage coming from the cradle. (wrap your big brain around that one)
and hey rv dont shoot my solutions down, they come from hot rod magazine, i didnt make them up

zteve06