Coil Spring Alteration
Coil Spring Alteration
(OP)
Assume: any car with original coil spring front suspension in new, unused condition. When a coil is cut to change the ride height, how does the loss of one coil affect the capacity of the spring, assuming the rear suspension is lowered the same amount? How does it affect the spring rate? Is the load carried, divided equally by all active coils? I have seen people cut a coil from a spring, takingout 1-1/2 inches of space, yet it drops the car sometimes 3 inches. Why? Everyone I have asked uses the by guess and by golly method of determining the results. I am not satisfied with that answer. If anyone here has some concrete knowledge on this topic, I would appreciate your opinion. Thanks!





RE: Coil Spring Alteration
The change in ride height is equal to the change in length of the spring /in the laden condition/ divided by the motion ratio of the suspension. the motion artio is a geometrical property of each particular suspension, except for beam axles.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Coil Spring Alteration
Take care.
Goodbye.
RE: Coil Spring Alteration
Coil spring rate, k = d*G/(8*NC^3) where;
d is wire diameter,
G is Modulus of Rigidity (typ. 30 X 10^9 psi for steel)
N is number of active coils (neglect ends), and
C is coil diameter.
So, if you reduce the number of coils and keep everything else the same, your spring rate will increase.
RE: Coil Spring Alteration
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Coil Spring Alteration
Norm