General Suspension help.

[BlitZ]

Spring Pre-Load - Compressing a spring in advance of adding a load.
Example: Using a 100 pound linear-rate spring, preloaded one-quarter inch, would take twenty-five pounds of force before it would further compress. In effect the spring will not compress until 26 pounds of force were applied. The spring in this instance will only move one-quarter inch when 50 pounds of force were applied, as opposed to the half inch the spring would have normally moved.

its interesting .. the question is : -

if the spring was 30cm high would the force at 30cm be the same if it was already compressed to 25cm...(where are the engineering students)

considering it was linear i thought it would be the same (as suggested its hooke's law)-


EXTRACT from HONDA-TECH

"sounds like both of you are confused about Hooke's law and how a linear spring works. "preload" doesnt affect anything about a springs function. a linear spring exerts the same amount of force from being compressed 0-1" as it does from being previously compressed at 2" to being compressed another 1", basically 2-3". what is effectively changed is the ride height when you adjust the amount the spring is precompressed and the static cornerweights of each wheel. the fancy shocks that allow you to separately preload the spring allows the adjustment of ride hieght independently to cornerweights. "


Also refer to the link u gave... They are talkain about a progressive spring in a coilover... not a linear spring

So basically u cant preload linear

[Muzz]

(where are the engineering students)

haha strange u should ask but im studing mechanical engineering.
Heres my opionion...

lets say we got a spring of 30cm with a 10kg/mm linear spring rate.
for now consider it OUT OF THE CAR.

lets say the spring is preloaded to 28cm, this is the same as compressing the spring with 200kg of force (2cm x 10kg/mm)

this in effect will mean the spring is pushing up with 200kg of force
(but it wont extend cus the shock/watever stops it from extending).

because the spring is pushing up with 200kg force, it wont compress at all until that force is equaled and exceded. 210kg of force will compress the unit 1mm, without the preloading, the unit will be compressed 21mm by a 210kg force.

After 200kg of force is reached on the spring, it will compress at the exact same rate, as usual.

consider 400kg force:
preloaded spring - unit compresses 20mm
unloaded spring - unit compresses 40mm

this is exactly what ek slut was saying

EXTRACT from HONDA-TECH

"sounds like both of you are confused about Hooke's law and how a linear spring works. "preload" doesnt affect anything about a springs function. a linear spring exerts the same amount of force from being compressed 0-1" as it does from being previously compressed at 2" to being compressed another 1", basically 2-3". what is effectively changed is the ride height when you adjust the amount the spring is precompressed and the static cornerweights of each wheel. the fancy shocks that allow you to separately preload the spring allows the adjustment of ride hieght independently to cornerweights. "

sounds to me like this guys confused
preload does effect a springs function, it causes the spring to push up with a force, which has to be equaled before its compressed any further.
I believe what ek slut was saying is correct.

to compress a coilover unit 2in, the spring will be compressed 2in.
to compress a coilover unit 2in with 1in of preloading, the spring will be compressed 3in, which obviously needs more force.

preloading a progressive spring, is exactly the same as preloading a linear spring, in that no compressin will be achived until the compressive force is exceding that which the spring is pushing out with. both springs work exactly as usual when the preload is met and exceded.

so yes u can preload a linear spring.
The efect is the same as preloading a progressive spring.