Off-road roll-centers

[BioMax]

This is sorta a 2 part question, okay mabey more...

...On a typical trophy truck, or really any other off-road 4-linked vehicle, the upper triangulated bars are, typically, "run" wide on the chassis and come to either a single point (ie. wishbone style 3-link) or close to each other on the rear end housing.

So, question one. Why would you want the roll-center to be "attached" to a moving part of the suspension? Especially one that moves as much as 36" or even more. Why not mount the bars wide at the rear end and narrow at the chassis?

Second, would an off-road truck benefit from a lower roll-center in the rear? What would be the problem with running a Satchell link or other similar system to lower said roll-center?

I know, always with the off-road questions, but it seems so "Black art" ish.

 

[NormPeterson]

Consider what happens to the roll center and the axle roll steer as the suspension moves through its range in both cases. It's not clear if any convergence in the lowers is present, but that will also have an effect.

I'm thinking that lower roll centers will mean more roll, and that in general that will leave slightly less suspension travel remaining on one side or the other to cope with bumps.


Norm

 

[patprimmer]

My experience with off road racing is that the ability to accommodate large bumps is more important than changes of castor and camber. The uneven ground changes over steer or under steer characteristics and available traction a lot more than a few degrees change in toe, castor, track, wheelbase, roll rate or camber.

Regards

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