Nohachi's suspension ramblings thread

[roman]

you get more lock with shorter steering arms, because for each mm of side to side movement of the steering rack, you get more degrees of turning on the strut.

Bump steer is the steering rack arm... end things... (tie rods?) moving through a seperate arc to the lower arm, causing it to pull or push on the end of the steering arm... non volountary steering inputs.

The amount (side to side) that the steering arm pulls or pushes via bump steer is fixed, but the degrees of movement that this causes is relative to the steering arm length.

People dial in shite loads of camber at the front, but is the increase in grip partially due to improved roll centre distributing load more evenly to the inside tire?

When you lower Mcpherson strut, the roll centre drops a hell of a lot lower than the COG, mostly because of the lower arm angle.
The goal of RCAs for mac struts is only ever move the roll centre back UP.
Closer to the centre of gravity.

looking at the diagram of what determines roll centre position, lower arm angle has the biggest influence, however angle of the strut, and also lower arm length (by virtue of tipping the strut over) will increase roll centre height also.

Getting the struts tipped over even just a few degrees more, for the same amount of camber, will give a better roll centre position.

Roll centre migration is interesting, because when your car rolls, the roll centre moves (drops!) further from the COG, causing more roll, causing further drop, causing more roll etc etc. So you need to run very hard springs.

A high roll centre allows softer springs for the same amount of roll resistance, so good in cornering and also bumps.

I doubt its possible to actually raise the roll centre higher than the COG, so any tricks to pull to raise it as high as possible should be good.

I'll need to check some actual measurements to find out what actual affect different configurations could have though, I dont know what the kingpin inclination angle is on widebody/narrow body struts. I just know that you end up with a few degrees of positive camber with MA61 etc struts in an AE86/carina/etc.