Coil Over Spring Rates??

Skankin · 08-31-2001, 03:54 PM

Actually the coil-over difference is a factor of 4! (for the front).

Torque = force * distance

Force = (spring constant) * compression

The compression is proportional to the radius. ie. circumference = 2pi*r

So, Torque = k (dist) * compression

Since you're doubling the leverage & the compression, it's equivalent to 4X that of the stock location. (Actually is something like 4.1 because the springs aren't vertical... so they're compressed even more than what the arm movement would indicate).

So a 250# coil-over is similar to a 1000# spring in the stock location. Fortunately, the unsprung weight is reduced and the spring's motion becomes the same as the strut's, so the ride is a little better.

So with coil-overs, you have to take the square of the ratio.

------------------
'89.5 5L LX, hatch, Medium Canyon Red, 155K Km (No winters), 5sp, 3.08, GT interior, a/c, Alpine CD, K/N, Crane PS91, Walbro 190 LPH, March Pulleys, Mr. Gasket 180 therm (HP balanced), 3 core rad, MarkVIII fan, Variflow controller, Polygraphite front bushings, FMS-5300B springs, 6 KYB's, 73mm Calipers, Maximum Motorsport 4pt chassis brace, Western Motorsport Racing's Sub-frame connectors. Re-ringed bottom end, conv. motor mounts, melling oil pump, FMS-C50 waterpump, GT40P heads (blended, polli

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08-31-2001, 03:54 PM	#1
Skankin Registered Member Join Date: Dec 1998 Location: London, Ontario, Canada Posts: 1,349	Actually the coil-over difference is a factor of 4! (for the front). Torque = force * distance Force = (spring constant) * compression The compression is proportional to the radius. ie. circumference = 2pir So, Torque = k (dist) compression Since you're doubling the leverage & the compression, it's equivalent to 4X that of the stock location. (Actually is something like 4.1 because the springs aren't vertical... so they're compressed even more than what the arm movement would indicate). So a 250# coil-over is similar to a 1000# spring in the stock location. Fortunately, the unsprung weight is reduced and the spring's motion becomes the same as the strut's, so the ride is a little better. So with coil-overs, you have to take the square of the ratio. ------------------ '89.5 5L LX, hatch, Medium Canyon Red, 155K Km (No winters), 5sp, 3.08, GT interior, a/c, Alpine CD, K/N, Crane PS91, Walbro 190 LPH, March Pulleys, Mr. Gasket 180 therm (HP balanced), 3 core rad, MarkVIII fan, Variflow controller, Polygraphite front bushings, FMS-5300B springs, 6 KYB's, 73mm Calipers, Maximum Motorsport 4pt chassis brace, Western Motorsport Racing's Sub-frame connectors. Re-ringed bottom end, conv. motor mounts, melling oil pump, FMS-C50 waterpump, GT40P heads (blended, polli