Spridget Front Springs

N

Neil J.

New member
My intent is to uprate the spridget from the 400# springs currently installed (for high speed autocross), up to 500#+ springs. I had a set of NOS "500 #" springs on the shelf, but they seemed softer than my 400# variety. So, I orderred new 500 pounders from WC. Thought I would take them to work and check out the rates on the Chatillon. Turns out, both the NOS and the new WC's measured 430# to 440# (starting from 0 compression height and compressing one inch.)

Are these both out of spec? Or should I start the measuring zero point from a precompressed point?
 
Try pre-loading the spring an inch or more then record the number and compress one more inch, record that number then do the math.
 
One of the factors when calculating spring rate is the number of active coils. It might be that at the installed height the coils are solid at the top or bottom thus reducing the number of active coils. If you can determine the installed height at normal ride height that's where you should check them. Then again it might just be that WC springs never were checked for actual rate adn they have always used the same design.
 
Kerry Foote":1f88ntfi said:
Try pre-loading the spring an inch or more then record the number and compress one more inch, record that number then do the math.
Click to expand...


Thats makes perfect sense to me, the car would be compressing the spring a certain amount just sitting on it's weight with driver, so on track compression and true spring rate starts at that point, not free height.
 
Thanks for the input. Sounds like the consensus is to start with some preload (simulating the installed spring with some weight on it) then compress one inch.
 
I use the WC springs also and they seemed soft to me but never have checked them so I will be really interested in what you find out. Please post resuilts.

Thanks
 
If you want to see the theoretical spring rate there are several websites that will calculate it for you. Do a Google search "coil spring rate calculator". You need to know the wire diam., the spring diam., and the number of active coils. It would be interesting to see what the theoretical rate is.
 
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