Stock leaf springs preload when lowered

[zteve06]

Hello all, I hope you and yours are well. Is there a way to keep the stock leaf spring preload at the stock ride height preload even though it is lowered? As you lower the car the tension on the springs dimenishes. I did look for the answer in the past forums but didn't see this. Best answer gets a two dollar bill.
Zteve06
Blk 02 Z06
Austin, Tx

[jub jub]

The spring pre-load is inherent to the spring itself. The adjusters just move the car in relation to the spring. It's not the same as a coil-over where you actually compress the spring to increase pre-load.

[XFordGuy]

You owe Jub $2 The ride height adjusters are just variable spacers.

[zteve06]

I figured I'd have to explain this further. As you tighten or loosen the top bolt (rear), the tension on the spring changes. This spring is a "fast bump" spring, one you need on a race car. It pulls down on wheel and pushes up at it's center, at normal ride height, this spring is bent or preloaded x amount, but is changed with ride height.
There was a thread a while ago about a guy asking why his vette "washed out" in a turn after he lowered it. I don't know if he got an acceptable answer, most peeps talked about an alignment, but I believe it is becuz when you lower the car you soften the fast bump, and your tires will chatter or skip over uneven surfaces instead of staying planted.
I need to keep or even increase that deflection even though it's lowered, I can't figure how to do that.
It seems you have to go coil over to lower without affecting suspension performance.
Zteve06
Blk '02 z06
Austin, Tx

[PerforminNorman]

For the life of me, I'm not seeing this in my mind.

[racingvette]

Originally Posted by zteve06

I figured I'd have to explain this further. As you tighten or loosen the top bolt (rear), the tension on the spring changes. This spring is a "fast bump" spring, one you need on a race car. It pulls down on wheel and pushes up at it's center, at normal ride height, this spring is bent or preloaded x amount, but is changed with ride height.
There was a thread a while ago about a guy asking why his vette "washed out" in a turn after he lowered it. I don't know if he got an acceptable answer, most peeps talked about an alignment, but I believe it is becuz when you lower the car you soften the fast bump, and your tires will chatter or skip over uneven surfaces instead of staying planted.
I need to keep or even increase that deflection even though it's lowered, I can't figure how to do that.
It seems you have to go coil over to lower without affecting suspension performance.
Zteve06
Blk '02 z06
Austin, Tx

Lowering the car only about an inch should not change the spring rate that much when the full weight has not changed.

Wash out, or whatever you call it, the biggest foul up is people totally ignore the shocks design.

With less shock travel no longer matches the valve setup the stock shock has that was designed for more travel which wipes out not only down but also up rebound.

As I did lowered the Vette the maximum, replaced shocks that were designed for shorter travel, valved for that, mounted them upside down to reduce un-sprung weight and added bump stops to bottom of travel.

Added using 12" wide rear wheels, mini tubbed and clipped ends of spring to not hit sidewall and zero suspension issues even above speeds of 230 MPH.
Point is select the correct designed shock for travel, valving and multi adjustable type and zero washout.

[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

[XFordGuy]

Something doesn't sound right. Mine is lowered 0.75" and I had to use a floor jack on the spring to get the nut on the stock rear adjusters when I had the control arms off recently.

[racingvette]

For safety I would fully check that spring has not cracked

[RocketSled]

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.
Zteve06

The weight of the car is the same no matter how high or low the adjuster is. If the bolt is retracted so far that the spring is unloaded, something else is taking the weight. You don't say if the rear suspension is bottomed out. But if you're not sitting on the Stops, the car must be hanging on the Shocks (which are pressurized).

My 02 is lowered all the way and it doesn't do this. The Spring is still under load. And I've never had the car bottom out on me. But I have '04 Shocks, which were different (I think, maybe a little shorter).

You definitely don't want to be driving the car with the spring like this.

[racingvette]

I would check the spring real closely for being cracked or due to exhaust design has overheated the spring

[zteve06]

I dont think you guys are understanding the problem. I have it lowered about an inch in the rear and there is pressure on the springs, this is where i had it when i started the thread. I want it lower than that but i need the spring to work. Ive inspected my springs and they are fine.
The point of this thread was to figure out how to offset the ride height preload change--i have found the answer in an article from hot rod magazine, which states that in order to adjust leaf spring preload after lowering the car, you must do one of three things: change the mounting points, or shim the springs, or have the springs re-arched.
I was already thinking shims, and that's how i found the article. Placing shims between the spring and the car will move it further away and when the car is lowered the spring will be bent the same as it was as stock ride height. The idea i had was to try to increase this preload to max with the car lowered to see if it will help my 60ft.
Most likely i will get coil overs and this wont matter, but i will look into shims, and let you guys know. I'm afraid ill have to keep that 2 dollar bill...maybe next time. thanks for the input...next time ill use pictures.
zteve06
blk 02 z06
austin, tx

[jub jub]

Get some coil overs that are fully adjustable and be done with it.

[racingvette]

Point I was making is my C5 is as low as it can get requiring shorter shocks,
as shown in image below
Mounted upsidedown, with bump stops and with 12 inch wide wheels the ends of springs shaved and have no preload problems as car handles at high speeds even in tight S turns with decreasing radius corners

It is all in the wheel alignment, shock valving and settings.

Originally Posted by zteve06

I dont think you guys are understanding the problem. I have it lowered about an inch in the rear and there is pressure on the springs, this is where i had it when i started the thread. I want it lower than that but i need the spring to work. Ive inspected my springs and they are fine.
The point of this thread was to figure out how to offset the ride height preload change--i have found the answer in an article from hot rod magazine, which states that in order to adjust leaf spring preload after lowering the car, you must do one of three things: change the mounting points, or shim the springs, or have the springs re-arched.
I was already thinking shims, and that's how i found the article. Placing shims between the spring and the car will move it further away and when the car is lowered the spring will be bent the same as it was as stock ride height. The idea i had was to try to increase this preload to max with the car lowered to see if it will help my 60ft.
Most likely i will get coil overs and this wont matter, but i will look into shims, and let you guys know. I'm afraid ill have to keep that 2 dollar bill...maybe next time. thanks for the input...next time ill use pictures.
zteve06
blk 02 z06
austin, tx

[zteve06]

Thanks again RV, but what im hearing from you is that you are happy with the handling of your car, but that doesn't mean your fast bump preload and/or rebound is where it should be, b/c it is lessenned with lowering the car without modifications.
I think your revalved or hieght spec. shocks are doing the work, but ive seen many posts of people keeping those springs on even with coil overs because they are doing something, and i believe they do less with lowering the car without mods.
When I finally put my aftermarket lowering bolts on the car I was quite annoyed that i hadnt seen any posts about this-- maybe this isnt fair-- but it seems that people lower the car for its appearance without having a clue as to whats happening in the suspension, and i'd bet my last two dollar bill that some people have wrecked on the street and track because of this issue...that's why i started the thread, better late than never.
zteve06
blk '02 z06
Austin, TX