So, I was reading this page, looking randomly for anything related to ARBs, springs etc. http://www.iwsti.com/forums/su ... ometimes-do-too-much.html

I noticed the values for the ARBs ('K'). If K = 467 lb/in, is that equivalent to (467 * 4.448) / 25 = 83 kN/m? Didn't realise stock ARBs were that stiff :\

It's because in real life manufacturers have to take into account the comfort factors. So as not to shake the fillings out of the passengers teeth. If real road cars had the same stiffness springs we put in our setups in LFS the driver couldn't see because of the jarring ride.

As there is need to put softer springs in the car in terms of comfort the ARBs need to be stiffer to give the handling charasterics we desire.

I understand the reasoning behind large stock ARBs, but since all I've ever seen quoted is the diameter of the ARB, I haven't had a real idea of the N/mm values involved.

Well if you consider a one ton car cornering so hard that its inside wheel is just about to lose contact to the ground them you have about 6 cm (500kg/8.3kg*mm^-1) of travel due to the ARB. Doesn't seem that stiff to me.

You have to consider the installation wheel:arb ratio. For an MX-5 this is about 1.85, so you're ARB wheelrate is 83 / 1.85² = 24. Which will be fairly stiff in comparison to the springs (possibly about the same figure for the front).