New shocks for backdraft!

[Cobra #3170]

Originally Posted by Kobura

I have to believe that you know what you are doing with these JRi shocks, but I didn't know that shocks used a measurement of pounds like springs. My understanding is that shocks produce pounds of resistance to rate of compression and extension, like in inches/sec or velocity. Springs, on the other hand, produce pounds depending on their spring rate and the amount of compression. Suspension adjustments are a mystery to me, but I can understand how modern race cars probably have a computer controlling the shock settings depending upon the speed of the car and the racetrack conditions.

You are correct that shock forces in pounds are generally measured in inches per second. I skipped some steps just to illustrate the value of JRI's.
The higher the spring rate you run the greater the required rebound damping is. This is greatly simplified because frequencies, unsprung mass and other factors are involved. My car operates generally in the 1" to 2" per second range in an autox. If I increase my spring rate I also need to increase my rebound damping to maintain the same rebound velocity with the higher rate spring. When I was running Penske's I switched from a 1200 lb spring to an 800 pound spring and had to re-valve the shock to accommodate the new spring rate. You could do that with a JRI by just readjusting the shock.
My Porsche has electronic automatic damping control based on velocity of the suspension and many other vehicle parameters. If it were legal in our class (SS) I would have JRI dampers so we could tune the car more precisely to surface conditions. There are aftermarket electronic controls for the Porsche shocks too but they are also not legal in our class. In general as grip on a given surface comes up due to temperature, rubber on the track etc we increase rebound damping and the inverse. We also can effect dynamic balance of the car. You need really repeatable adjustments in a shock to do that and in my opinion JRI's are the best generally available short of the Multimatic DSSV shocks used on the new Ford GT and several GM products, very expensive though. Hope this helps.
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