Riff

Interesting topic! By no means any sort of guru, but the less bump damping for increased spring rate does make sense. In Larry's example above, a spring will overshoot equilibirium when subjected to an impact. But when comparing 2 springs with differing spring rates and subjected to the same impact, the spring with the lower rate will overshoot the equilibrium compression by more than the stiffer spring. The damper's job is to control this excess motion, the spring with less rate would require more from the damper to control the motion than the stiffer spring. So less bump for the stiffer spring rate.

I have no data to back this up, but makes sense to my engineering mind. Now if I could only really tell how this feels on the track, I might be able to do something with it...

Cheers!

924RACR

Very nice and interesting data Geoffrey - thanks for posting it! I've always wondered how tuning shocks is done with data...

kurt M

Another simplistic way to put it. Spring rate and bump damping cannot exceed a value or the car body will move up. The key is to keep the body from changing ride height and to keep the tire on the pavement as it undulates. More spring = less bump or you exceed a set-point and the chassis moves before the suspension travel is used up. You need enough spring and bump to keep the wheel from hopping around like a basketball but not so much that the car does the hopping.

tip of the iceberg.

Geoffrey

Yea, it is cool data and that is only the tip of it. With math functions, you can begin to look at roll/pitch rates, suspension roll frequency and a whole host of other things.

SundayDriver

I think he is subtly pointing out that you forgot to post the data - oops.

924RACR

You're too subtle for me, Mark! LOL No, I didn't notice that, I was just digging the description and the pretty graphs...

Larry Herman

I am not really certain of where it would be more applicable. Moton now makes 4 way shocks; maybe they are not certain either. The movement of the suspension due to road conditions is certainly with much greater velocity, but with less momentum. The movement of the body is slower, but has a lot of momentum due to its mass. I am running 3 way Motons, and have found the need to adjust all 3 settings.

I still feel that once the shocks are properly set for dampening and not to compensate for other problems, the ratio of compression to rebound will be relative to spring stiffness, and not absolute to it. I just ran this past a friend of mine who is crew chief for a Grand Am team, and he told me that some do find that they can turn the compression down with stiffer springs because they were running overly high compression to compensate for too soft a spring to begin with. This makes sense too, but is not the gist of my arguement.