Differential Failures

[Peter Orban]

The differentials fail when using different diameter tires because of lack of
proper lubrication.
If you ever taken apart a normal differential, you can see that those side- and
pinion-gear bearings are not designed for continuous rotation. Those are just a
pin and a hole with a sliding fit, no rolling elements, no bearing inserts, no
pressure lubrication, etc.
Of course it could have been engineered properly, exept it would have cost more
money to produce.

Peter

On Oct 11,  8:47am, quattro-request at audifans.com wrote:
...
>
> Message: 7
> Date: Tue, 10 Oct 2006 23:58:59 -0700
> From: "urq" <urq at pacbell.net>
> Subject: Differential Failures
> To: <quattro at audifans.com>
> Message-ID: <009801c6ed02$badf6d40$6d00a8c0 at fasthp>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
>
> ...
> Open differentials ... it always seems there are some strong opinions on
> that one ... and I happen to be one of the ones that has a difficult time
> seeing how there would be much difference in stress on an open diff with
> identical rolling diameters on its outputs as compared to one with different
> diameters.  I think of the situation where the vehicle goes perfectly
> straight and the rolling diameters are identical.  Of course if this were
> indeed the case you would not need a differential ... but assuming one is
> there, all of the drive torque is transferred through the same gear faces in
> the differential.  Eventually you would have to expect wear on those
> surfaces.  In normal operation those drive forces are distributed between
> all the faces of the bevel gears, and the wear should be pretty even.  Under
> most driving conditions a differential is feeding two different rates more
> often that it is driving the same rotating rates ... and I'd argue that many
> of the situations where the differential is "differentiating" are the times
> where the most torque is passing through the differential.
>
> The one case I might actually buy into an argument for long term damage
> resulting from differences in rolling diameters is in a Torsen.  That said,
> so many Audis have Torsen center diffs, and the center diff is the one that
> is most likely to deal with differentiation between its two output shafts
> ...
>
> Steve B
> San Jose, CA (USA)
>
...