[TR] Stag diff rebuilt

Randall tr3driver at ca.rr.com
Fri Jul 11 09:04:44 MDT 2008


> Was wondering how you're Differential rebuild went...

"What a long, strange trip it's been."
<G>

Just finished putting it back together last night; hoping to get it back in
the car this weekend.  But it's kind of stiff, so I can't quite shake the
idea I should pull it apart again ... haven't made a final decision yet.

One of the frustrating things was that it turns out this diff is not
originally from a Stag, even though it was sold to me as a Stag diff and
fits in the car fine.  I learned this when one of the new bearings didn't
fit; turns out the diff is from a 2.5PI Estate, which has a larger input
bearing than the Stag does.  After having another wrong bearing overnighted
from TRF (my fault, wrong part number), I finally got the right one by
looking up the Stanpart number on Rimmers website (they cover the 2.5PI
Estate) and ordering that P/N from TRF.

> Were you able to find various shims?

Shims turned out to be no problem.  I did buy some from MMC, but wound up
not using them.  TRF had everything necessary, though, I just bought from
MMC because I could run over there and pick them up.

> How did you "set up" the ring and pinion clearances?

Tedious trial and error.  Actually I was fortunate, 3 of the 4 original shim
packs turned out to still be correct (after replacing shims damaged in
disassembly).  The contact pattern between ring & pinion turned out perfect,
first time.  I've heard this is usually the case, if they were correctly set
up before; as the bearings are precision machined and match very closely.
So, I started out by grinding the old bearings a bit, so they would slip in
and out of place easily, and used them for initial shim checks.

But the replacement input bearing turned out to be a lot different than the
one that came out, so the pinion preload was way off.  The original shim
pack was .030", I got down to .003" before the preload was within spec.
That's 7 trial assemblies (.030", .028", .012", .010", .008", .005", .003")
plus a few extras I did to convince myself that the shims were actually
controlling the preload.  Fortunately, the input bearing can be removed
without damaging the shim pack, so I didn't have to use new shims every
time.

Took some photos, so maybe if it works out well, I'll write up a tech
article on the process.

Randall


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