Porsche -

I know, but the point is not that, its to provide a correction factor...

If you independantly calculate the weight on each tire, and see if it adds up to the total weight on the rig.

As the coefficient of friction times the weight on the tire equals the propulsive force it can apply before slipping, it will help to derive the answer we were seeking...how much downforce do you need to push the truck.

Obviously, you sweated some details, and saw that each suspension type has optimum ranges...and are interested in what the limiting factor is in determining the point of diminishing return for tire weighting.

I think that this will allow us to see it.

This is of course possible because we have evolved from whether a revolver provides ANY down force when unfolded a bit, etc...and we can now look at traction from a universal perspective...

Something that will work for any suspension, as far as tire weighting required to move forward, etc.

I have some data on this from work, but I'm not in the office...

But, roughly...to roll at a constant velocity (not slip), if

v = velocity
R = radius
w = angular velocity
f = frictional force
N = normal force

v = Rw

If its not a split mu surface, the open diff is typically ok...unless the drooped tire slips, and for the LSD rear, if the breakk away torque is reached, etc.

I think we can figure out what would slip from there.

Whatcha think?



The simple leverage for the axle, even if there were NO dropped side suspension connections at all...just a disconnected axle sticking out from the stuffed side works out to almost 600 lb of down force, not counting the weight of the axle, tire and leaf pack...that's assuming about 15" from the stuffed tire edge to the center of the stuffed leaf pack...and that 2,500 lbs (A 1/4 of a 5k lb truck...) was resting on the one stuffed leaf...

...That leverage would work by taking the force on the stuffed side leaf, and applying the mechanical advantage of the lever arm created by the axle.

It would be like Jeff was laying on the ground, with his head under one end of a steel girder....and the other end was supported by an equal sized rock...

...And I placed a 2,500 lb weight on the girder about 45" from his head, closer to the rock....

That's about the force on Jeff's head....which appears rock like, so I'm sure he'll be fine.



So, that's at least 500+ lbs of leverage forcing the axle down on the drooped side, no matter what suspension was there...PLUS the weights of the axle, tire and leaf pack, rear drive shaft, etc...lets say a MINIMUM of 800 lbs or so.