KSport Coilovers: All About 'Em

[Brad Roberts]

Pics would be great! Your comment about the car having harmonic issues threw up the red flag for me then the flat plates..

Have you "zip tied" the shock shafts to find out much travel you are currently using on the street?




B

[insite]

Originally Posted by Brad Roberts

Pics would be great! Your comment about the car having harmonic issues threw up the red flag for me then the flat plates..

Have you "zip tied" the shock shafts to find out much travel you are currently using on the street?

after i ran the calcs, it turns out the harmonic issues were legitimate. the front ride frequency and rear ride frequency were only 3% apart. this is horrible for low speed ride quality.

as for the zip tie trick, haven't tried it yet. good idea! what do i do, just tighten a zip tie around the shafts, trim the excess, and go for a ride?

[Brad Roberts]

Correct! With the suspension in full droop, place a zip tie on all 4 corners. It is the *cheapest* form of data acq I can give you.. put it through some twisties!

I'm now wondering if having the rear mounts that protrude UP into the tub, would have also cured your issue with harmonics (by lengthening the shaft travel) and not changing the ride height.



B

[insite]

Originally Posted by Brad Roberts

I'm now wondering if having the rear mounts that protrude UP into the tub, would have also cured your issue with harmonics (by lengthening the shaft travel) and not changing the ride height.

shaft travel wasn't the problem; the issue was a genuine harmonic frequency issue. i calculated the natural frequencies of the front & rear suspensions based on spring rate, motion ratio, etc. They are only 3% different front to rear. what this means is that at lower speeds when a bump is encountered, the front is compressed while the rear is extended. this causes excess pitch / dive motion. this is cured in road car suspension design by running a rear ride frequency that is between 10% and 20% higher than the front. this allows the rear of the car to 'catch' the front over bumps so the car stays flat.

[Gary in BR]

This has been a great thread.

Insite, are you of the opinion that if I raise the rear of my car a half inch my ride quality will be better?


Thanks
Gary

[insite]

Originally Posted by Gary in BR

Insite, are you of the opinion that if I raise the rear of my car a half inch my ride quality will be better?

that really depends on some things. if you tell me the height of the front of your car to the fender, the height of the rear of your car to the fender, and your spring rates, i'll calculate a good setup for you.

[Gary in BR]

I will get the fender heights tonight and the springs are the springs that came with the Ksports.

Thanks for the help.

Gary