Originally Posted by yessamgerg

Your misconception is that 0.6" is anywhere near enough clearance to the bumpstop. You measured that without a driver in the car, the driver sits almost entirely over the rear axle so let's say 125lbs on the rear axle. You probably didn't have a full tank of gas so we will say another 60lbs, entirely on the rear axle. You claim your car is 130 lbs lighter than stock, let's say 65 lbs is on the rear of the car. That means while driving a stock car you have 125lbs more on each rear wheel. To correct for load at the spring 125/0.575=217lbs. An 8k spring is 450lbs/in meaning 0.47" of compression vs your value. Through in the fact that most people forget to relax their control arm bushings and that equals most people are sitting on their bumpstops while actually driving their cars. Additionally on your car will hit the bumpstop with only a 1.25G bump (in industry 1G is the car sitting still), this is a tiny bump at which point your 450lb spring becomes a 2000lb/in spring. Unless you drive around on glass you are going to be constantly hitting the bumpstop. As you go closer to stock weight with a driver and topped off tank you will be riding around on the bumpstops the entire time.

Originally Posted by B serious

Like I said...I'm not insulting you. I just don't understand it the way you're explaining.

Can you please explain what you're saying from the top?

I'm willing to agree with you if you can explain it.

Originally Posted by B serious

I clocked my bushings.

what does the airspring charge of the DFV equate to in LB?

Originally Posted by DavidNJ

It depends on the diameter of the shaft, the diameter of the piston, the height of the air chamber (as a proxy for volume) when it is charged, and initial nitrogen pressure.

For a 5/8" shaft (probably larger than the DFV), 36mm piston, 5" of travel, 5" height of the nitrogen chamber and an initial charge of 180psi you would have about 50# of initial force and a rate at ride height of about 6 lb/in. With a 550 lb/in spring (10 kg/mm), That would mean maybe 1/10th of inch static ride height and about 1% change in spring rate...neither really noticeable.

Originally Posted by SakeBomb Garage

@B Serious

yessamgerg is correct. I understand that its confusing that the spring force is more than the weight of the car but think about the lower control arm. The entire unsprung mass needs to be supported by the outer ball joint right? The lever arm of the ball joint is longer than the lever arm of the damper. Therefor the damper force is higher due to its shorter lever length. The reason that the shock tower force is greater than the weight of the car is that the lower control arm actually pulls down on the chassis due to the lever effect.



If you check out our post on motion ratios we derive the steps for how to calculate spring force from wheel loads. Its also important to take into account the gas preload which is about 50+/- pounds on the DFV.
https://www.s2ki.com/s2000/topic/116...motion-ratios/