CoilOVerKid Posted January 19, 2012 Report Share Posted January 19, 2012 Re doing my suspension front and rear and need some basic spring length and diameter. For the front coilovers I should be using a 8" long 2.5"ID spring? And rear should be a 8" long 3"ID? please correct me if mistaken thanks for your time. Quote Link to comment
Uber Deaf One Posted January 19, 2012 Report Share Posted January 19, 2012 Fronts are 2.5" ID rears are 3" ID, yes. 8" up front seems to be a pretty good height with coilovers. Rear spring height all depends on what you want your ride height to be. An 8" spring is little on the low ride height side but will work fine. Quote Link to comment
CoilOVerKid Posted January 19, 2012 Author Report Share Posted January 19, 2012 ......... An 8" spring is little on the low ride height side but will work fine. How low would it sit compared to a stock non sagging spring?? And thanks for the quick reply Uber. Quote Link to comment
Uber Deaf One Posted January 19, 2012 Report Share Posted January 19, 2012 I can't upload any pics right now because Photobucket thinks I'm on a mobile browser (lol) but if you have Facebook here's a pic of how my car sits right now. The tires are 205-50-15s, and my rear springs are 9 1/4" tall with a 1/4" spacer. An 8" spring will be tucking a fair amount of tire. I personally will be going to 8" springs soon. http://www.facebook.com/photo.php?fbid=10150539905514525&set=a.10150148195504525.300929.663924524&type=3&theater Quote Link to comment
datzenmike Posted January 19, 2012 Report Share Posted January 19, 2012 Height of spring means nothing. Your ride height is a function of the weight supported by the spring in question. If your right front corner weighs 650 pounds and the spring rate on that corner is 350 PSI then it will settle down 2inches. The spring rate in PSI per inch can be roughly calculated if you know: the thickness of the wire, diameter of the coil from center line across to center line, the number of coils and the modulus of spring steel (a constant that very very roughly described as the elasticity of a material) For example my stock 710 front strut springs are 0.50" thick,. The diameter of the coils is 5.0625" across the centerlines and there at re 6.5 coils. spring rate = modulus of spring steel X wire diameter4 -------------------------------------------------------------------- 8 X number of active coils X mean coil diameter3 11,250,000 (a constant) X (0.500" X 0.500 X 0.500 X 0.500) _____________________ 8 X 6.5 X (5.0625 5.0625 X 5.0625) 703125 ________ = 6746.80957 104.21 PSI The stock 510 front springs are about 100PSI so I would guess that the 710 must be very close. Generally 510 guys run 200 to 300 PSI springs in the front but don't get carried away. These are very stiff for the street. I removed one coil and this increased the rate to 123PSI or about 20% Quote Link to comment
docbainey Posted January 20, 2012 Report Share Posted January 20, 2012 Height of spring means nothing. Your ride height is a function of the weight supported by the spring in question. If your right front corner weighs 650 pounds and the spring rate on that corner is 350 PSI then it will settle down 2inches. The spring rate in PSI per inch can be roughly calculated if you know: the thickness of the wire, diameter of the coil from center line across to center line, the number of coils and the modulus of spring steel (a constant that very very roughly described as the elasticity of a material) For example my stock 710 front strut springs are 0.50" thick,. The diameter of the coils is 5.0625" across the centerlines and there at re 6.5 coils. spring rate = modulus of spring steel X wire diameter4 -------------------------------------------------------------------- 8 X number of active coils X mean coil diameter3 11,250,000 (a constant) X (0.500" X 0.500 X 0.500 X 0.500) _____________________ 8 X 6.5 X (5.0625 5.0625 X 5.0625) 703125 ________ = 6746.80957 104.21 PSI The stock 510 front springs are about 100PSI so I would guess that the 710 must be very close. Generally 510 guys run 200 to 300 PSI springs in the front but don't get carried away. These are very stiff for the street. I removed one coil and this increased the rate to 123PSI or about 20% +1 Everything that he said, but coil springs are generally rated in inch pounds not pounds per square inch. Quote Link to comment
Uber Deaf One Posted January 20, 2012 Report Share Posted January 20, 2012 Height of spring means nothing. Your ride height is a function of the weight supported by the spring in question. If your right front corner weighs 650 pounds and the spring rate on that corner is 350 PSI then it will settle down 2inches. Assuming we're all talking 510s.... weight is roughly the same, especially in the rear. And I'm sure everyone knows springs compress a little bit when the springs are supporting the weight of the car, with softer springs compressing more than stiffer springs. When I say this spring will give you this ride height, I'm not saying it'll be EXACTLY like this, but will be pretty close. Just wanted to clarify... I don't like to get all technical because most people don't understand those kind of posts. Quote Link to comment
CoilOVerKid Posted January 21, 2012 Author Report Share Posted January 21, 2012 I understand what you mean Uber, I was only asking to get a rough idea of potential ride height I know it won't be exact. But thanks for clarifying Quote Link to comment
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