Best Coilover Shock Spring Compressor

[TheJDMan]

The rear suspension is the Alston Chassisworks G-Link. The shocks are around 5deg from vertical. I don't have any actual weights at this time. It just looks to me like a 10" spring would be a better fit. To keep the same load as the 12-200, should I go with say a 10-250? I looked at the ridetech online coil sping calculator but without actual weights I'm just guessing.

[darren@ridetech]

I thought the G-Link was designed w/ for a 5" stroke shock tho?
What are your compressed/extended dimensions?

[jorge]

Sorry to sneak in here, but I think this can help you find you’re a number close to your corner weight: If the shock stroke is in fact 4.1, you could just multiply the shock compression of 60% that you said the car had when dropped and multiply that times the total stroke.

.60 x 4.1 = 2.46” of compression

Since you said the spring rate was 200 lbs/in AND assuming you don’t have any preload on the spring when you measured AND if the coilover is close to vertical AND since the rear has a motion ratio close to 1, you can just multiply the spring rate times the compression of the shock.

2.46” x 200 lbs/in = Sprung corner weight around 500 lbs

If you plug in 500lbs in the ridetech calculator under corner weight and 0 for unsprung weight (since sprung weight = corner weight – unsprung weight, and since you can’t enter the sprung weight directly think of it like this: 500 sprung weight from above = 500 – 0)

Then plug in a 4.1” stroke shock with a 10” spring and shock angle 85 degrees. The spring rate will come out to 163 lbs /in that’s WITH a preload of .62”. Since you don’t have a spring compressor, enter a custom preload of 0 and you will get a spring rate of 200 lbs/in.

200 lbs/in sounds right since you said that your 12" 200lbs/in spring gave you around 55-60% shock compression which you were fine with, if you were to get a shorter spring and use the same spring rate you would get the same amount of shock compression. Only your ride height and spring compression compared to total spring length would differ. And if the shock is compressing around 2.46" and 60% of a spring is usable without coilbind, then that will leave the spring around 40% compressed with 60% compression left which is pretty good. Math:(10" spring * .60 = 6" of usable travel, 2.46 / 6 = .41 or around 40% the spring compression). I'm thinking if the 200lbs/in feels fine, stick with it and go to the 10" spring with the same spring rate. This is all assuming the stroke is 4.1"

This is at least what I'm thinking personally