Spring rate calculations

D

Dean Lampe

Member #023
First Name
Dean
Last Name
Lampe
I have found this formula very helpful in the past. It will help you identify a spring rate given a specific desired wheel rate. Morris Clement, who some of you have met at Run and Gun, is a 3 time national SCCA champ. He built an awesome cobra and based on his advice I set my GT40 wheel rate to 300lbs for the track and 200 to 225lbs for the street. My GT40 was a dream to drive and was very fast through the twisties.

http://www.leskoracing.com/wheelrate.htm

I hope that helps.
 
Well I thought about that last night. I would think the total length D1 would be the track width and the D2 would be the opposite wheel to the shock mount. It would be interesting to measure that and see if the spring rate calculates to something that seems reasonable.

When the drivers wheel hits a bump the pivot seems to be the opposite wheel. What do you think?
 
That was the only answer that made sense to me too, but I thought maybe I was missing something (it has been known to happen---DOH!).

Since I'm not with the car to actually measure I'll throw some educated estimates at it for a 3 link FFR. D2=60, D1=50 using 350# springs calculates to a wheel rate of ~206. Seems within the range of possibility. I'll get actual measurements tonight and plug both front and rear into the equation.

Thanks for the info!

Jeff
 
Last edited:
Watching NASCAR this morning, and learned something I haven't heard. They said that an increase of 1lb. of tire pressure results in a 60lb spring rate increase. Not sure I understand why though.
 
You must log in or register to reply here.
Back
Top