Bump Stops as Third Spring

[rikgray]

Given the standard push rod rocker suspension;

What would be the best bump stop to add progressive rate to compensate for compression from new aero forces?

More specifically I have 3" of travel (exposed shaft at droop) on my shock using 1600 lb/in spring, 200 lb preload, with 1-1/2 in bump stop of unknown properties. The car is bottoming out with 3-1/2 in ride height. I don't want to raise the car any more and stiffer springs are not available.

[problemchild]

If you go on eBay and search RACING SHOCK BUMP STOPS.
Select a bunch that are cheap (probably red or yellow) and try a few with plastic washers between each one. Jump on your car and decide what you think is best.
Very similar to the very expensive ones from Haas or Dynamics. Perhaps the same.

Tip. If you need plastic washers, cut them from cheap plastic square gutter drain pipes.

[Lotus7]

Given the standard push rod rocker suspension;
The car is bottoming out with 3-1/2 in ride height. I don't want to raise the car any more and stiffer springs are not available.

You're using up 3.5" of static ride height with aero forces on a 1600 lb/in spring?
Must be quite the aero package :-) What car is it?

[lowside67]

You're using up 3.5" of static ride height with aero forces on a 1600 lb/in spring?
Must be quite the aero package :-) What car is it?

Either quite the aero package... or very low motion ratios!

-Mark

[rikgray]

Ordered some RE Suspension RSW series bump stops. Assorted durometers.

They have good data sheets that allow some design. I like the near linear force/deflection curve.

Jumping on the car only moves the springs 1/8", need 3/4" for proper test. Starting with bump stops at 50% of spring rate.

The suspension travel noted is on the track, and a combination of aero and driving dynamics.

[lowside67]

With respect, if jumping on the car produces only 1/8" of travel then 3.5" would take 28x as much force as your body weight is applying. That would seem to be in the neighborhood of 4000lbs+ depending on your body weight which seems very unrealistic for downforce production - is there any possibility you are not bottoming the car but rather maybe your floor is flexing, etc?

Mark

[ProstWest]

Aforementioned "driving dynamics"

[rikgray]

Jumping on the car only moves the springs 1/8"

compressing the spring, not the measuring the chassis.