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Home » Public Forums » GMCnet » Newby Question - Repack Rear Wheel Bearing - '73 - 26" (How To : Repack Rear Wheel Bearing - '73 - 26")
Re: [GMCnet] Newby Question - Repack Rear Wheel Bearing - '73 - 26" [message #323834 is a reply to message #323828] Wed, 13 September 2017 10:04 Go to previous messageGo to previous message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma:
Senior Member
If you know this already, don't be offended by my emphasis.

The important thing to remember about those rear castle nuts, and this
mistake has caused a world of damage, is that tightening the nut to spec is
only for the purpose of SEATING the bearing. You tighten as you turn the
wheel drum to make sure the bearing is fully seated--it will be when the
drum turns evenly even though the nut is tight. Then you LOOSEN the nut a
half turn and then tighten to finger-tight to adjust the bearing and to
line up a hole for the cotter pin. The hub should spin freely with only
seal drag (or brake-shoe drag for part of the rotation--brake shoes barely
touching.

The common error is to tighten that nut to 25-30 ft-lbs like the manual
says, and then cotter it in place. That is TOO TIGHT, and the bearing will
overheat and burn up. I've seen hubs that were melted because of that. The
tightening is just to seat the bearing, then you LOOSEN and then
finger-tighten to adjust.

I confess I've never done my rear wheel bearings, though the above
procedure is standard for all spindle-mounted wheels, and only the front
bearings on a GMC require special tools and techniques. I have
documentation showing that the rear brakes and wheel bearings (plus one
drum) were replaced before I bought my coach, which though that was 15
years ago, was only 25,000 miles ago. When I lift the wheels, there is no
play and they rotate smoothly even when the wheel is removed (the mass of
the wheel and tire can make rough seem smooth). The brake lines are still
in visibly good condition, the bleeders are not corroded, and the brakes
are all in adjustment (meaning: the adjusters work). Next year, I am
planning a disk-brake and reaction-rod conversion, and doing that will
replace everything anyway, so I'm good for now. Check your documentation
and look at the condition of things in the back before assuming that you
have to take it all apart. The old saying is that if you didn't do it
yourself, it wasn't done, but you can spend a year doing stuff if you take
that statement too seriously. If you can find documentation and if you can
do an informed inspection, you can prioritize your efforts without undue
risk. If the brake lines show cracks, and the bleeders are rusted in place,
do it all--bearings and brakes on the rear. Then you won't have to do it
again for a long time.

The front bearings are another matter. They will not show much in the way
of symptoms when they have failed, and the only way to check them is to
disassemble them. I had a front bearing that was spun (there wasn't any
documentation that the front bearings were done, and unlike the rear, the
front brakes can be done without disassembling the bearing). I discovered
this because I had removed a half-shaft and the caliper, and when I pulled
the caliper off, the hub fell off. That's not supposed to happen! The
half-shaft stub axle and caliper were holding it all together. The outer
bearing had spun in the knuckle. There was no external evidence of this
fault.

Rick "not retired and still working in stages after 15 years of ownership"
Denney




On Wed, Sep 13, 2017 at 9:43 AM, Wayne Rogewski wrote:

> ...
> If you have the maintenance manual, that has a solid write up on how to go
> about it, and provides the torque specs for the rear castle nut. THAT IS
> CRITICAL to set the load on the bearings before you put the cotter pin in
> it. Its been documented in several threads on this board, and also in the
> manual, You really do need to follow that to the letter. and you need a
> torque wrench and socket that fits the rear castle nut. No way around that.
> The manuals can be downloaded on Bdubs site if you dont have the book.
>
>
>


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