thickie wanting info......

[magpies]

am I correct

2000lb (900kg approx) car with equal corner weights = 500lb at each wheel.

front springs are 400lb/in and near vertical. 4/5 of distance from chassis mounts to hub mounts.

using height adjustable coilovers.

with no pre-load on the spring does the damper compress (each corner) by 1"

If the above is correct then.....

If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper (2000lb total at the wheels) and so statically the dampers do not compress?

If pre-loaded between zero and an inch then that allows the static ride height to be adjusted between the two extremes.

Is this theory correct?

then what is the vertical load through the dampers if they are set at 30deg from vertical? presume this would be as per triangle where horizontal vector pushes but has no-where to go?

Edited by magpies on Tuesday 1st October 19:56

[autosportgpeng]

magpies said:

am I correct

2000lb (900kg approx) car with equal corner weights = 500lb at each wheel.

front springs are 400lb/in and near vertical. 4/5 of distance from chassis mounts to hub mounts.

using height adjustable coilovers.

with no pre-load on the spring does the damper compress (each corner) by 1"

If the above is correct then.....

If I now wind up all the spring platforms by 1" does it give 400lb preload to each damper (2000lb total at the wheels) and so statically the dampers do not compress?

If pre-loaded between zero and an inch then that allows the static ride height to be adjusted between the two extremes.

Is this theory correct?

then what is the vertical load through the dampers if they are set at 30deg from vertical? presume this would be as per triangle where horizontal vector pushes but has no-where to go?

Edited by magpies on Tuesday 1st October 19:56

Pre-load is the condition where the damper is at full extension and yet you've wound the spring platforms up further compressing the spring, such that in order for the damper to compress at all you must first exert a force more than that stored in the spring. So 1" of pre-load in your example means that there would be 400lbs stored in the spring which would have to be overcome before the damper would move.

If the damper is not at full extension then you are not pre-loading the spring, all you are doing is increasing the ride height of the car, and the spring will react to any loads put on it the same as with a lower spring platform.

I just make that point because so often this confuses people.

So yes a 400 lb/in spring will compress by 1" if the corner weight of the car is equivalent to 400 lbs at the damper. If there is 1" of preload in the spring then there will be no movement, until it sees 401 lbs. In your example your maths is a bit wrong though. It's the other way around. With the damper at 4/5ths of the length of the arm and if mounted at an angle the wheel/tyre has a mechanical advantage over the spring/damper therefore your spring rate will be something like 625 lbs/in for 1" of travel to take the corner weight of the car.

As soon as you have spring preload, then statically the ride height of the car will not vary at all, as you've used up all the dampers travel in order to preload the spring. On coil overs you can only adjust ride height with a zero preloaded spring, or a mechanism that allows the installed length of the damper to be changed (like in a pushrod system).

[magpies]

cheers, yes not realised that ride height only affected up until start to preload the spring.....but obvious once thought about.

and yeah I had realised my maths were incorrect ......loads on a balance beam