whose in control

[pintojoe]

If you have a solid rear wheel drive axle controled by skewed upper,lower four link control arms and add a panhard rod in a effort to lower the rear roll center who is in control? At some point would a geometric bind be reached and cause heavy loading of the tires by locking the travel?

pintojoe

 

[GregLocock]

Yes, it is quite easy to arrange a 5 link system like that so that it is not capable of free motion - in fact many modern suspensions on the road today would be locked up but for the compliance in the rubber bushes.

This is not a good idea for live rear axles in partiuclar, ours are designed so that kinemtaically they are linkages, not structures.

The only way to analyse these locked up linkages properly is to do a compliance study, or start making approximations.





Cheers

Greg Locock

 

[NormPeterson]

I'm completely in agreement with Greg.

People have added PHB's to triangulated 4-links, but I think the best results came when the PHB wasn't trying to force a lower roll center. The greater the amount that you try to lower the RC the more the splayed uppers will fight it. In those cases, the gain was in improved lateral axle location rather than in RC location.

People have also added a PHB and then either removed one of the splayed uppers or replaced its bushings with soft foam for a so-called "poor man's 3-link". This better accommodates lowering the RC, but I'm not at all sure what it would "feel" like to drive as the remaining upper is still splayed.

Relatively recently, a few real 3-link conversions have been developed within the aftermarket (or in some cases perhaps still under development). Unless you're competing in a class where such a mod is not permitted, this would be a better way to go.

Norm

 

[pintojoe]

Thanks for the reply's.

pintojoe