Side Notes 3

The basic suspension theory may be describe as: -

ma+kx=0     [the a should be written as x with a double horizontal dot above]

The entire term is coolly pronounce as m x double dot + k x = 0

where: -

m = mass

a = acceleration

k = coil spring's stiffness

x = displacement (travel)

m times a = force - therefore: -

force + kx = 0

Now imagine we have a 4kg/mm coil spring and it travels 10mm - therefore: -

force + (4kg/mm times 10 mm) = 0

This would be the normal conditions. However for other coilover users who did not upgrade properly, assuming they don't have enough height. Often the coil will be compressed to give strength to uphold the car's weight and so push it higher till requirement. In this case say the compression of the coil is 10 mm.

This will ultimately make the entire suspension behave like: -

force + (4kg/mm times 20 mm) = 0

Notice the top 10 mm has become 20 mm?

It is no wonder why so many coilover users complain their setup is too hard and not comfortable. This is highly unfortunate, if only consumers will make some effort to study the fundamental science of what they are trying to do / buy.

The mathematical term above does not take into account of gravity, lost of kinetic energy from the coil, damping (absorber), cornering G forces application to actual mass altering weight, un-sprung mass, and lots more.

However the simple formula already settle the 1st two most important parameters, which is initial_condition = resting condition and 2nd the traveling stroke. From this we know how strong a spring rate is required for how heavy car's corner mass going through which corner at how fast and experiencing how much G-force. Aren't science cool :)

back to Day 2 - Deliver the front strut

This understanding was explained to a friend, who understood immediately and made provisions for modifications to improve his situation.

He managed to increase his ride height without compressing the coils now. He simply machine a tough Nylon and insert it above the coil.

However this solution causes the absorber travel stroke to reduce by one inch. This is not desirable as the total absorber travel is only around 3 inch. Taking one whole inch away has reduce it's full effectiveness by 33%.

I suggest to him to machine another bolt as an adaptor to compensate for the lost of absorber stroke.

I'm no suspension expert, just trying to learn along the way using fundamentals from School of Acoustics and Electronic Engineering of Salford University in their course of B.Eng. (Hons.) Electroacoustics. The course is now ceased and replaced by B.Sc. (Hons.) Acoustics. It's the same anyway.