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Differential

To: alpines@autox.team.net
Subject: Differential
From: "Fisher, Michael" <m-fisher2@onu.edu>
Date: Mon, 30 Apr 2001 14:38:29 -0400
I finally have my Series V operational again. It seized the inner pinion
bearing in the differential in the summer of 1999. Finding the bearing(s)
to rebuild the differential was no problem. However, adjusting the load and
pinion depth was a MAJOR problem. My problem was no, i.e. none, nada, shims
on the pinion shaft. 

I put the differential back together, in the reverse order that I took it
apart. I tested the preload on the pinion shaft and had less than 2 lbs
when the manual calls for 6-12 lbs for new bearings. I put it back in the
car just to test it out (these was last summer), and sure enough, it worked
fine, but made as much noise as before, (from what I can gather, similar in
magnitude and tone to what other people attribute to a loose crown gear). I
pulled it back out and checked the crown gear bolts, they were up to specs
in torque. the preload on the bearings was wrong. I tried to make some
shims to work, we are talking 0.003" to 0.020" in two different diameters
and four different thicknesses. I was unsuccessful. 

I tried buying the shims, no luck, and even considered contracting a real
machinist to make them for me. Fotunately, Rick had them in his latest
catalog, and I got them in November.  After 3-4 days of adjusting the
number of shims (they go between the pinion gear and the inner bearing and
the shoulder on the shaft and the outer bearing, I finally gor to 12 lbs
preload and I believe the correct mesh of the pionion gear and the ring
gear. I tested it this past weekend, runs great! Still a little bit of a
whine, but nothing like before. I think this is from the new bearings and
u-joints running in.

Now I have come across much "jury rigged engineering" in this car. The
DPO(s) were really something. But since I was the one that first mentioned
the casting sand in the block (noticed by my machinist when I rebuilt the
engine in the spring of 98), I wonder if my shim problem applies to more
cars than we think. Has anybody else had to rebuild their differential and
run into the same problems?

p.s. A very easy rear axle puller is the brake drum and four 3" bolts.
Remove the bolts holding the drum and replace the current bolts with the
long 3" bolts. Then the brake drum will slide on the long bolts acting as a
pull hammer to ease the axle out. Works great as I can attest, since I have
pulled the rear axles more than I wish to admit over the past five years!
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Mike Fisher
Associate Professor of Physics and Astronomy
Ohio Northern University
525 South Main Street
Ada, OH  45810

phone:  419/772-2740
fax:    419/772-1888
e-mail: m-fisher2@onu.edu
web:    http://www.onu.edu/user/FS/mfisher2/
        http://www.virtue.nu/percy/

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