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Lateral grip: Optimize for wheel bump travel or shock stroke?

thread800-469230

Lateral grip: Optimize for wheel bump travel or shock stroke?

Lateral grip: Optimize for wheel bump travel or shock stroke?

(OP)
Context
Reverse trike on double-wishbone IFS with coilovers

Objective
Improve lateral grip
Decrease roll

Method
Reduce load transfer
-decrease CG
--lower ride height
Current static ground clearance: 6"
Target static ground clearance: 5"

Current static ground clearance of 6" - target static ground clearance of 5" = 1" drop @ wheel * 0.84375 motion ratio = 0.8" @ shock
Current 16" extended shock rides at 15.5" - 0.8" = 14.7" new shock ride

Replacing with a threaded body shock of the same 16" extended length (11" collapsed / 15.87" extended) gives:
15.87" extended - 11" collapsed = 4.87" usable stroke
14.7" - 11" = 3.8" bump / 4.87" usable = 75% bump
15.87" - 14.7" ride target = 1.2" droop / 4.87" usable = 25% droop

Replacing with an 18" shock (12" collapsed / 17.87" extended), travel would be limited by packaging to 17 1/8". However,
17.125" packaging - 12" collapsed = 5.125" usable stroke
14.7" - 12" = 2.7" bump / 5.125" usable = 52% bump
17.125" - 14.7" ride target = 2.5" droop / 5.125" usable = 48% droop

Does that look right?

What would you do for a 100% street performance vehicle: 3.8" bump : 1.2" droop, or 2.7" bump : 2.5" droop?

RE: Lateral grip: Optimize for wheel bump travel or shock stroke?

Running out of travel in compression is a lot worse than running out of travel in extension ...

RE: Lateral grip: Optimize for wheel bump travel or shock stroke?

First thing I'd want is a set of tires with more grip. You can drop the c.g. with a rim change while you are at it.

Get a VBOX and measure some key performance indicators (understeer, steering gain, max lat) and run a constant radius or constant steer test. Results from this will help you gauge your changes even with the tire you have. You might even need more motor to get more grip.

RE: Lateral grip: Optimize for wheel bump travel or shock stroke?

Agree with Brian. Consider adding a soft bump stop as well.

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