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Re: [GMCnet] Final Drive Intermediate Axle questions [message #322497 is a reply to message #322496] Tue, 22 August 2017 15:59 Go to previous messageGo to previous message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma:
Senior Member
The hanger bearing and bracket is the same between the 3.21 and the 3.07.
The hanger includes a cup that retains the bearing in the outboard
direction, and a bolt-down retainer on the inboard side. Of course, the
final drive itself retains it in the inboard direction, and the half-shaft
and steering knuckle retains it in the outboard direction, so the hanger
only needs to keep it positioned against the float of those constraints.

The slinger is pressed down over the axle and provides a grease-filled
labyrinth seal to protect the bearing on the inboard side. Likewise, the
axle has a dust cover that is pressed onto the back side of the axle flange
that provides the same protection on the outboard side. It's shown in
Figure 7 of X-7425, page 3C-5.

The 3.21 shaft is a bit thinner in the middle than the 3.07 shaft, but the
bearing seats are the same and they use the same bearing. The only
difference in the shafts otherwise is the spline on the end of the shaft
that inserts into the final drive.

My next step is to try to make sure the bearing is seated fully in the cup
of the bracket. There's no way to press on it directly without removing the
slinger, but there's a gap under the edge of the slinger that I think I can
get under and tap around it to make sure it's tight in that cup. The fit in
the cup is not, I don't think, all that tight. It's a tighter fit on the
axle, I suspect. It's a symmetrical ball bearing, as expected given that
there's only the one bearing.

Thing is, I can't make that bearing anything but glass-smooth when I
manipulate it off the coach, even when I put the bracket in a vice and lean
on the axle while turning it. But I'm still experimenting. That's what
makes me suspect it's pushing the axle too far into the final drive. I am
going to really go over that bracket with a straightedge and see if it's
been tweaked in a way that is hard to see.

Rick "looking for the collective experience, if there is any" Denney

On Tue, Aug 22, 2017 at 4:01 PM, James Hupy wrote:

> Rick, what locates the bearing axially on the jack shaft? I am not familiar
> with the 3:21 final drive. But I know that the Cadillac vs Olds are
> different from each other. It seems from your description that when the
> hanger is loose, that the shaft turns quietly, but when it is tightened, it
> binds up. Just wonder if the replacement bearing is not positioned
> correctly? That's all I got. Sorry.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Aug 22, 2017 12:41 PM, "Richard Denney" wrote:
>
> 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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--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com
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