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Differential rebuild rebuild

To: "shop-talk" <shop-talk@autox.team.net>
Subject: Differential rebuild rebuild
From: "Rex Burkheimer - WM" <rex@txol.net>
Date: Wed, 4 Apr 2001 13:30:35 -0500
This may be off-topic, but hey, it's content ;)

Hey guys, I need some help from you more experienced mechanical sorts.
I run a 1st Gen RX7 in SCCA road racing.  Installed the GSL rear axle, but
went to the smaller early driveshaft to get the changeable U-joints.  This
involved swapping the pinion flange out to the earlier small yoke. I used
and impact to remove the original, installed the smaller one of an '81, and
ran it down with an impact.
   Last race (1st ever with this car) the front pinion bearing failed in a
big way after about 20 laps/35 racing miles.  Now, the rear axle came from a
long-dormant parts car, so  the bearing could have been borderline from the
start. But I wonder if I should have done something different when
installing the yoke - torque it etc?

Part 2 - So I pulled the differential. Only thing bad was the front pinion
bearing. I changed out both bearings.
The races were not as tight in the housing as wheel bearings typically are.
They just tapped out, though they weren't loose.Is that normal?  No sign of
any rotation on the outside of them.
I assembled with the new crush sleeve, torqued to specs, but the sleeve did
not collapse.  It still had about 1/8" of longitudinal play. So I put the
old
sleeve back in, torqued to spec, and it feels fine - no play, and a slight
drag. I did not measure the drag per the manual, but it was slightly tighter
than I would tighten a wheel bearing.  Am I going to get away with this?  Is
there a better way of doing this, short of the exact factory manual
procedure with the fish scale or miniature torque wrench?  Preload drag was
only supposed to be about 15#, which is basically not much.

Beyond that, I changed out 1/2 of the friction disks, assembled the diff
section, and set it back in the side bearings. Could not retain the original
side play adjustments, so I left one side as-is, adjust the other in until
the backlash was minimal.  Checked the contact pattern with grease and it
looked good.

So what should I have done different? What would have made it better?
Shops get $300-$400 to do a rebuild. What would that include that I couldn't
do or might overlook?

BTW, I have a running joke going with the wife. Every time I've discussed my
progress, I have called the unit a different name.  At first it was
accidental, and Celia would get this puzzled look. After that, I started
looking for additional terms, and now I've run out.

So far I've used:

differential
Center-section
rear-end
punkin
diff
carrier

What else?

Can't wait to tell her about putting the "punkin" in the "banjo housing" ;)


--
Rex Burkheimer
Parts Plus Marketing Director  WM Automotive Whse., Fort Worth TX
"I want to put a ding in the universe."   --Steve Jobs





Rex Burkheimer
Parts Plus Marketing Director  WM Automotive Whse., Fort Worth TX
"I want to put a ding in the universe."   --Steve Jobs

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