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[GMCnet] Final Drive Intermediate Axle questions [message #322495] Tue, 22 August 2017 14:40 Go to previous message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma:
Senior Member
Sorry, I can't think of any way to present this briefly.

After installing the new final drive, and reinstalling all the stuff I had
had to remove, my last step was installing the intermediate axle, which
extends from the final drive through a hanger that bolts to the starboard
side of the block, and provides the flange for the starboard half-shaft to
bolt to. This axle just inserts into the final drive, and the spline
engages the spider (or, in the case of this rebuilt 3.21, the planetary
gear). The manual says to adjust it around to find the middle of play, and
then tighten the two bolts that hold that hanger in place good'n'tight (50
foot-pounds). Those bolts have specially hardened and thick serrated
washers to hold the hanger in that position.

I anticipated this would be easy, but, of course, it's the easy stuff that
surprises us.

1. I can't find the middle position--the play accommodated all extremes of
the holes in the hanger. I looked for a position that provided easiest
rotation (not easy to discern) and didn't seem to distort the seal (also
not easy to discern).

2. The real problem is that when I tighten those hanger bolts, I get a very
loud bearing noise in that hanger bearing when I spin the axle by hand. I'm
expecting some roughness provided by the rattling of the gears in the final
drive, but this sound was definitely coming from the hanger bearing. That
bearing is new, and smooth as butter when not bolted up to anything. When I
hold the hanger in what seems to be the best position but don't tighten it,
I get what I think is only final-drive noise when I spin the axle.

Yes, I have filled the final drive with gear oil.

Manny had never experienced this issue before, but these hangers come from
salvage yards and be slightly tweaked if the car was wrecked in a way that
affected the right front wheel.

So, possibilities: A. The hanger isn't quite straight straight, and it's
not holding the bearing square with the axle. B. The hanger is too close to
the final drive (or the bearing isn't seated all the way in the hanger) and
it's binding axially. C. The slinger (inside dust cover) is rubbing on
something and ringing when the hanger is tightened.

Questions:

Has anybody experienced this issue?

Does anybody know if there is a standard piece of pipe that I can use to
press against the slinger that covers the inside of the bearing? Or any
other advice on how to reseat the bearing? The manual calls for a special
tool, but it just looks like a piece of pipe that fits over the axle in a
press that bears on the recessed part of the slinger that pushes directly
on the bearing.

Manny suggested that I could move the axle to the old hanger (they are all
the same), given that I have a press, but I can't see how to get the
slinger over the larger diameter of the seal race and spline on the
final-drive end, and I think that slinger is just sheet metal that is
crimped on the axle when the right pressing tool is used. Or, I'm missing
some obvious point about how it's attached. The slinger covers the retainer
to provide a dust shield for the bearing seal. I'm just not sure I won't
mess up what I have. He also suggested that I could "adjust" the hanger so
that it hangs at the right place, but my attempts to do that have not
solved the problem. I even wondered if I could put a thin washer under the
hanger, but I don't know what the axial tolerance is supposed to be.

Alternative is to ask Manny to ship me a replacement 3.21 FD intermediate
axle if he has one available, and send this one back for his far more
expert inspection.

Rick "advice welcome" Denney

--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com
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