Well, if you subscribe to the theory that all fasteners should tighten in
the direction of rotation, then your allen screws backed out because they
weren't designed to tighten in the direction of rotation. Given that all
auto manufacturers got rid of left-handed lug nuts decades ago, I don't
really subscribe to that theory. I had a similar thing on my race car's
transaxle, but it was on the right hand side. In that case, the allen
head screws WERE tightened in the direction of rotation, but they backed
out anyway. The cause was tranny oil seeping out from the center of the
flange.
The thing about a diff or transaxle flange is that under acceleration and
braking, the splined joint in the center of the flange is rocked forwards
and backwards. If there is play in the splines, there is room for oil to
seep out and loosen any fasteners. The fasteners themselves could also
loosen from getting rocked back and forth. I say clean the flange, make
sure there is no seepage underneath, and put new allen screws in there
with blue Loctite. I also safety-wired mine.
DGreimel@aol.com wrote:
>
> Fellow listers,
> Perhaps one of you engineer types could explain why a ring of large allen
> screws that hold the left side axle flange to the differential on my BMW all
> backed out and left me without motivation. They were all still there and
> only one was bent. There was absolutely no warning. It just would not move
> when I wanted to move off from a traffic light 20 miles from home. The
> flange would normally rotate counter clockwise looking at the bolt heads.
> Thanx
> Don
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