Spring Poundage?

[burr_2000 1]

hey all, i came across coilover springs with no id markings. is there a way of getting the poundage through measuring thickness or a formulae?

cheers,neil

[swordfish210 20]

Yeah we did it at Uni once. Basically we sat the spring on a digital scale (an accurate bathroom scale would suffice) and we mounted a DTI so the needle was on the top of the spring and then compressed it by exactly one inch. Once you have compressed it take a reading from the scale and that will give you a lb/inch for the spring.

[AdamP 0]

There are formulae but they are generally quite inaccurate due to them not having a whole number of coils and measuring difficulties. The method Mark suggested works but can be quite difficult / dangerous / inaccurate with stiff springs.

 

Are there any decent competition car specialists around you? Most will have a jig setup to do the above in a safe, controlled and accurate manner (or a machine that does it all automatically).

[Cameron 16]

I don't think anyone uses a formula to test spring stiffness, if they want to be super accurate they generally use a spring stiffness tester (funnily enough). As Adam said using a formula won't be accurate but it may well give you a ball park so you can make a sensible guess as to what the stiffness is. I imagine you could get it accurate to 20lbs/in, and springs generally go up in 20-25lb increments. I can imagine the formula to be something horrific though!

[mickie 3]

you could always just post up what the springs are like and we could try and guess a round figure..

 

how long ? how many coils, not marking down the half cut end spring as full spring

 

how thick is the coil ? whats the over all ID ? bigger at the top than the bottom or not ?