Home » Public Forums » GMCnet » NAPA SKF-21771 rear bearing seal fails the 0.25" test
| Re: [GMCnet] NAPA SKF-21771 rear bearing seal fails the 0.25" test [message #318160 is a reply to message #318159] |
Mon, 29 May 2017 16:51   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
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Senior Member |
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Ken, you are absolutely correct. Do not seat the seal below the outer part
of the hub casting. Leave it a bit "proud" meaning sticking out a bit for
insurance purposes. Jwid.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On May 29, 2017 2:38 PM, "Ken Henderson" wrote:
> Looking through my parts this morning I found 6 of the 21771 seals.
> They're all OLD stock -- no less than 10 years old since I've had them in
> my storage for that long.
>
> All of the 6 are NAPA-labeled. 4 are relabled Chicago Rawhide; their outer
> circumferences are Green. The other two are have only NAPA labeling; their
> outer circumferences are Black.
>
> Using a 1/4" screwdriver bit as the clearance gauge, I tested each of the 6
> on a flat Formica surface. Here are the results:
>
> Green #1 -- Rubber barely touched the gauge
> Green #2 -- Rubber very slightly deformed by the gauge
> Green #3 & #4 -- Rubber noticeable deformed by the gauge, WAG 0.003"
> Black #1 & #2 -- Rubber very obviously deformed, WAG 0.010"
>
> All of this has piqued my interest, CRS having taken care of most of my
> memories from when this topic was originally broached some years ago.
> Aside from the contention that the out-of-tolerance seals will allow the
> seal to touch the bearing, I don't recall the details of the problem. I DO
> recall, however, that somewhere (which I can't locate in any manual now)
> there was a requirement that the seal be seated proud of the rear of the
> hub. In fact, I still have an un-machined aluminum "seal seater" which
> Duane Simmons had Ragusa cast. We were going to use those to make a
> special tool for properly seating seals. The aluminum proved difficult to
> machine, so we gave up that idea. I did, IIRC, make one from steel which
> worked well. BUT, I can remember neither its dimensions nor its location.
> :-( Could it be that the problems with at least some of the
> out-of-tolerance seals are really caused by incorrect installation? Does
> anyone know where the official instructions are for R&R of rear wheel
> bearings and seals?
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, etc., etc., etc.
> www.gmcwipersetc.com
>
> On Mon, May 29, 2017 at 12:52 PM, Bruce Hislop
> wrote:
>
>> So I went to NAPA thos morning to pick up the SKF-21771 rear bearing
>> seals. I brought along a 1/4 hex bit to test the seal which actually
>> measures
>> 0.247". It fails the test as your can see in these photos.
>>
>> http://www.gmcmhphotos.com/photos/g7044-skf-21771-rear-
>> seal-fails-test.html
>>
>> Any ideas?
>>
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