| Rear bearing seals, still an issue [message #318024] |
Fri, 26 May 2017 06:19  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Its been about 5 years and over 20K miles since the rear bearings were redone so its time to do them again.
I bought some new bearings and seals from a former GMCer a couple of years ago. The seals are 8974S in a National box. I tried the 1/4" clearance trick and these fail. From my understanding, the seal will sit too close to the bearing and the rubber will touch the bearing causing it to get damaged. Then the grease can leak out and toast the bearing.
Has anyone come up with a consistent good part number? or a work-around for a seals that fail the 1/4" test?
Thanks
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Rear bearing seals, still an issue [message #318026 is a reply to message #318024] |
Fri, 26 May 2017 08:02  |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Bruce,
You want to try and find the SKF 21771. These work, but you should still do the 1/4 inch test incase they have changed. Use some 1/4 inch copper tubing. They are available from NAPA and other auto parts supplies.
http://www.gmcmhphotos.com/photos/general-pictures/p45146-rear-bogy-seal.html
JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan
> On May 26, 2017, at 7:19 AM, Bruce Hislop wrote:
>
> Its been about 5 years and over 20K miles since the rear bearings were redone so its time to do them again.
>
> I bought some new bearings and seals from a former GMCer a couple of years ago. The seals are 8974S in a National box. I tried the 1/4" clearance
> trick and these fail. From my understanding, the seal will sit too close to the bearing and the rubber will touch the bearing causing it to get
> damaged. Then the grease can leak out and toast the bearing.
>
> Has anyone come up with a consistent good part number? or a work-around for a seals that fail the 1/4" test?
>
> Thanks
>
> --
> Bruce Hislop
> ON Canada
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Rear bearing seals, still an issue [message #318030 is a reply to message #318027] |
Fri, 26 May 2017 13:16 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Senior Member |
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So, how do you remove the rear seals?
When removing the rear seal:
Remove axle nut and large washer
Remove outer bearing
Now thread axle nut back on shaft
With a jerk pull the tire and wheel off
That should capture the inner bearing and seal with no damage
This seal can be reused if not worn out.
On Fri, May 26, 2017 at 7:27 AM, gene Fisher wrote:
> I guess you read here .?
> http://gmcmotorhome.info/rear.html#BEARINGS
>
>
> On Fri, May 26, 2017 at 6:11 AM Wally Anderson
> wrote:
>
>> RF_Burns wrote on Fri, 26 May 2017 06:19
>>> Its been about 5 years and over 20K miles since the rear bearings were
>> redone so its time to do them again.
>>>
>>> I bought some new bearings and seals from a former GMCer a couple of
>> years ago. The seals are 8974S in a National box. I tried the 1/4"
> clearance
>>> trick and these fail. From my understanding, the seal will sit too
> close
>> to the bearing and the rubber will touch the bearing causing it to get
>>> damaged. Then the grease can leak out and toast the bearing.
>>>
>>> Has anyone come up with a consistent good part number? or a work-around
>> for a seals that fail the 1/4" test?
>>>
>>> Thanks
>>
>> October 2015 we got SKF 21771 seals from NAPA and they passed the 1/4"
>> test.
>> --
>> Wally Anderson
>> Omaha NE
>> 75 Glenbrook
>> Megasquirt III injection
>> Bob Stone hydroBOOOOST
>> Manny reaction arm system
>> Branscombe Kelsey Hayes park brake
>> http://wallyandsue.blogspot.com/
>>
>> _______________________________________________
>> GMCnet mailing list
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>>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
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--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: Rear bearing seals, still an issue [message #318046 is a reply to message #318024] |
Sat, 27 May 2017 08:24 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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If I had just waited till the end of the day, I came home to find my GMCMI spring mailing with the Parts Interchange.
The bearing seal issues are shown on page 9.
Lots of other good info in the front pages as well.
Thanks Kim and everyone involved with compiling and printing this great resource.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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