Spring Rates

[7ishNZ]

What is the accepted starting place for spring rates for a R1 powered locost? I was thinking about 250 lb/in front, 200 lb/in rear. Mainly for road and a bit of track.
Thanks.

[11Budlite]

Check out this build site. Jeff did a beautiful job on his car and I'm sure he has some good info here:

http://underwood-racing.com/constuction.htm

For reference, my Zetec powered Birkin runs 300/front and 175/rear.

[slngsht]

for the front you have to factor in the motion ratio as there is alot of variability depending on suspension geometry. for most solid axle sevens the rear springs are pretty much vertical, so it's easier to compare. I'm running 200 lb/in springs in the back of my car, and it weighs way more than a bike engined car will. my car weighs 1750 lbs.

[andrew7]

I have no idea, its the reason I went with air shocks. I did not want to spend $800 then turn around and spend another couple hundred on an assortment of springs. I'm sure people chuckle at the thought of my seven riding on air and not SPAX. The car is so much above my skill level now, and you can't find the limits on the road only a track. Your guestimations sound OK but as Mazda said a lot of things can affect it.

Here is a 3 page thread on spring rates.
http://www.locostusa.com/forums/viewtopic.php?f=5&t=891