[Fot] Spring Rates

[Randall]

> There is a specific 
> section dedicated to understanding coil springs, leaf springs 
> and torsion/sway bars including formula's for calculating 
> rates for what you have. 

Thanks, Ken, I'll have to pick up a copy.

Sometimes it's good to get independent confirmation of the calculations.  Here's a shot of the test bed I threw together to check
leaf spring rates.
<http://s258.photobucket.com/user/TR3driver/media/Tools/DSCF0008.jpg.html>

You could easily do something similar for coil springs.

The area of the piston in the air cylinder is known, so it's easy to calculate force from air pressure applied.  (There was also a
table supplied by the air cylinder manufacturer.)  The cylinder came from eBay, $30 IIRC; the rest came from Home Depot or MMC.
Hard to see is the second needle valve, to bleed pressure off.  Since leaf springs have a lot of internal friction, I measured
deflection at several points going both up and down, then used Excel to fit a line to the results.

The setup confirmed what I knew going in : The new leaf springs I got from TRF were way too stiff even for racing, let alone street
use.  But I was also able to check some original springs, and weed out the weak ones.

-- Randall