Re: anti-wrap via radius arms (was RE: JPOR: Bigger lift options.)

[Larry Soo <lars@xxxxxxxxx>]

Ed Tapanes wrote:

>I've seen many links and anti-wrap devices try to duplicate the driveshaft
>arc.  Why is this?  I would think that the driveshaft arc is the last one
>you'd want to duplicate with a fixed length arm of any sort (since the
>driveshaft's length will change as the suspension cycles, hence the slip
>splines).

Doh!  I was hoping no one would ask for clarification of what I said because
it's hard for me to describe it with words and I am loathe to do ASCII "art"
but here goes:

When I said "arc," it was for lack of a better word.  I was thinking about the
lateral positioning of of radius arm where it connects to the axle tube and
the
tcase skidplate.  Obviously, we can't mount the radius arm on top of the diff
because it can't clamp it, so it must be mounted to one side of the diff.
Now,
let's suppose it's mounted very closely to the diff and runs roughly parallel
to the driveshaft.  That means it mounts very closely to the tcase rear output
as well.

When the axle twists up, the radius arm's twist will be similar to the
driveshaft's because they will be close to having the same axis.  If the
radius
arm clamps closer to the spring pack (ie: further away from the diff), it will
travel a different arc when viewed from behind.  In fact, if you imagine the
diff to be the rotation point, the driveshaft will not move (for the sake of
this example) while the location where the radius arm mounts to the axle will
arc around it.

Now, it isn't always possible to mount the radius arm close to the diff and in
those cases, to minimize the different arc between the radius arm and
driveshaft, the radius arm should mount close to the center of the tcase
skidplate.


...lars (probably didn't explain this very well)



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