[Gmcnet] 100,000 mile (and more) bearing service

[Ray Swartzendruber]

Gene, I believe the knuckles can be drilled for the zerk quite easily without removing
the knuckles.  Last fall, I serviced the bearings and installed zerks to grease next
time per Dave's recommendations.  It is easy to see (or measure) where the spacer is
located in the knuckle when it is out of the knuckle.  I took a center punch and
punched the knuckle right in the center of where the spacer is when it is installed.
I then got a 6" long 1/8" drill bit from Grainger's and drilled a hole from the inside
out, that is, from the bearing side out, then installed a press in zerk.  To finish
the job, I ground a groove around the periphery of the spacer, and across the OD and
down the sides with a Dremel grinder to provide a grease path from the newly drilled
hole to the bearings.  This was with Dave's blessing via a telephone conversation we
had before doing it.  This was done with the knuckles off, but there is no reason why
it couldn't be done with the knuckles mounted on the coach with everything removed.

As you did, I would like to reinforce the importance of seeing Dave's presentation.
He knew a lot about bearings from his life's work, but has gathered a tremendous
amount of information from the used hubs and knuckles he gets returned to him.  He has
found the fit to be critical to keep from spinning bearings and to provide the proper
axial clearance between the rollers and the races.  If the outer race has too much
press fit, that clearance disappears.  Too little press and the races can move and/or
spin with disastrous results.  Similarly, he has found finish to be critical.  A
machined finish as opposed to a ground finish leaves "machining ridges" and results in
very little contact with the bearing races.  This makes for very poor heat transfer
and can also cause loosening and spinning.  He has found the depth of the bore in the
knuckle to vary all over the map.  Thus, to properly locate the inner seal, you have
to locate it with respect to the bearing seat (bore depth).  If it is not in far
enough, the face seal is totally compressed and becomes hot and is destroyed in short
order.  If it is in too far, the face seal doesn't even contact the C/V joint housing,
and the radial part of the seal may not seal against the C/C joint housing.  He has
come up with a tool to properly locate the inner seal.  He has found the ears on the
retainer bend when tightened up and need to be straightened before reinstalling to
assure a good clamp load to keep the outer seal and outer bearing races in position.
In catastrophic failures, he has even seen the part of the retainer that seats against
the seal bent outward so when assembled the retainer doesn't even contact the seal!
So flatness of the retainer face needs to be checked.  A lot of stuff that you would
never think of as being a problem.  I'm sure there are others, but these are just a
few things that I recall.  The point is, you really need to hear his presentation
first hand to get the full impact, and if you don't understand something, he is very
good at answering questions.  These bearings don't have to be the problem we make them
out to be if they are serviced properly in the first place.  I am going for another
30,000 miles on top of the 55,000 the bearings already have on them before I look at
them again (now watch one go out on the way to Delaware!!).

By the way, Dick Paterson's presentations fall into the same category.  There is a lot
of information presented, and a "paper" would not do them justice. Also, liability of
a limited information "paper" in the wrong hands is worrisome to both Dick and Dave. 
Sorry I got so wordy, Regards, Ray

-----Original Message-----
From: gmcnet-bounces at gmcers.org [mailto:gmcnet-bounces at gmcers.org] On Behalf Of Mr.erf
ERFisher
Sent: Monday, August 11, 2008 6:22 AM
To: gmcnet at gmcers.org
Subject: [Gmcnet] 100,000 mile (and more) bearing service


I bring this up now because:

1  If you have not serviced your front wheel bearings - it has not been done 2  GMCWS
and GMCMI are coming and you need to discuss this, there 3  Bdub (give that man
$10,000) has us back on line just in time 4  Dave Lenzi ( at Santa Rosa) showed how to
get more than 80,000 miles on bearings 5  There are at least 4 ways to service the
front bearings ( more later) 6  Knuckle removal, (most recommended), causes major
damage to front end components 7  All of us will have our knuckles drilled for a zerk
in the future.

Dave Lenzi has refined the knuckle zerk technique to an art form, go see his talk.
This procedure was first purposed by our forefathers, Alex Burch and Wallace;
http://www.gmcmhphotos.com/photos/showphoto.php?photo=5987

Dave has refined the technique ( with knuckle / shim modifications, and technique) so
we no longer have to worry about blowing out the seals when we grease the bearings.

Volvo suggests not servicing the front wheel bearings because more problems are caused
by the service than wear and tear on the bearings.  I believe this is more than true
for the GMC motorhome.

So talk about this at the rallies.  We need a way to drill for the zerks without
removing the knuckle (not very likely). At least, we need a way to drill the knuckles
the next time they are removed for bearing service.

Lessee, there are 8,000 GMCs on the road, times 2 equals 16,000 knuckles to be drilled
;>)  Big job here

gene


-- 
Gene Fisher -- 77PB/ore/ca
"Give a man a fish; you have fed him for today --- give him a URL and -------
http://gmcmotorhomeinfo.com/ Alternator Protection Cable
http://gmcmotorhomeinfo.com/APC.html

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