FSU Double wishbone knowledge transfer
- Nathan Roberts
Requirements for FSU:
Energy efficiency is key
8 cm vertical displacement of the wheel under maximum force case.
90° angle between suspension and arms under maximum force case.
20 mm scrub ratio.
Remember to check Camber, steering axis inclination angle, and the rotation axis for the wheel.
Avoid wheel collisions at all costs.
Steering gets wheel access priority, so suspension works around them.
DFA, DFM, and confirm bolts will work
Nice things to have:
The wider the wishbone, the better it is under force cases, but you lose material strength.
Long short arm double wishbone is the best.
Trapazoid shape for the 4 bar linkage of the double wishbone suspension.
Angled chassis connection points (~10°) make long and short arms easier.
Smaller bearings/ smaller load rate would be good
Information on shocks:
Mountain bike shocks are appealing due to their low weight and small size.
Springs can be removed and changed on the same shock as long as it can support that level of spring coefficient (for this car, we need ~50-100 N/mm).
Length should be determined by the needs of the 4 bar linkages (we’re guessing ~9 inches).
Length is reported as eye-to-eye length.
Linear springs are much easier to calculate, but progressive and air-based suspensions could be used on future cars once we have more experience.
Lower spring rate requirements are preferred when possible.
PDF’s of rough pages used for explaining:
