NAPA SKF-21771 rear bearing seal fails the 0.25" test

Richard RV

Richard RV

Well-known member
Jun 15, 2015
1,207
557
113
Whereabouts unknown
Ken,
I opened a can of worms for myself when I took a look at someone's coach after the GMCMI. There was too much play in the passenger rearmost wheel,
and that lead to discovering a loose bearing cup, broken brake shoes, an out of round drum on it's last legs, etc.

Trying to put it back together, I'm trying to locate seals that pass the 1/4" test and after hitting several auto parts stores and opening a dozen or
more boxes from several different brands, found that none of them passed, or were even that close. From the drawing in the manual it appears as you
say, that there's no way the metal could contact the bearing. So where did the 1/4" test come from? Does it matter?

Richard V.

> John,
>
> IIRC, you're thinking of the front wheel bearing seal. From the drawing I
> posted, it appears virtually impossible for the metal to touch the
> bearing. But the rubber is separated from it only by about the distance
> the seal should be left proud of the hub.
>
> https://drive.google.com/file/d/0B3XquSIYjDleenNDM1BHQlNHa1E/
> view?usp=sharing
>
> Ken H.
>
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
'77 Birchaven TZE...777
 
Richard,
The issue occurs when the seal housing is driven in flush with the hub housing. The trick is to leave the seal housing sitting slightly proud of the
hub as shown in the diagram below:

https://drive.google.com/file/d/0B3XquSIYjDleenNDM1BHQlNHa1E/view

Dave Lenzi makes a tool to install the seal to the proper depth.

--
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
 
I bought four that fit last year. Two were SKF, the other two were CarQuest boxed. Both had the same number stamped in the metal... not the part
number. The SKF ones had orange sealer painted on the outside, the CarQuest didn't. Obviously from the same source though.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
Richard,

What Bruce said.

Ken H.

Trying to put it back together, I'm trying to locate seals that pass the
> 1/4" test and after hitting several auto parts stores and opening a dozen or
> more boxes from several different brands, found that none of them passed,
> or were even that close. From the drawing in the manual it appears as you
> say, that there's no way the metal could contact the bearing. So where
> did the 1/4" test come from? Does it matter?
>
 
Bruce,

It should be noted that Dave found a supplier that provided seals that met HIS requirements THEN manufactured the tool to install
them.

The tool may or may not work with Chicago Rawhide / SKF or seals made by other manufacturers.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Bruce Hislop
Sent: Friday, April 20, 2018 7:16 AM
To: gmclist
Subject: Re: [GMCnet] NAPA SKF-21771 rear bearing seal fails the 0.25" test

Richard,
The issue occurs when the seal housing is driven in flush with the hub housing. The trick is to leave the seal housing sitting
slightly proud of the hub as shown in the diagram below:

https://drive.google.com/file/d/0B3XquSIYjDleenNDM1BHQlNHa1E/view

Dave Lenzi makes a tool to install the seal to the proper depth.

Bruce Hislop
 
This issue was originally brought up by Dave Lenzi at the Fall 2010 DuQuoin
Convention where he had discovered several sets of rear bearings had an
issue with metal in the grease. Dave said there were 2 manufactures that
were OK. They are the Chicago Rawhide 3857731 and the SKF 21771. The SKF
is sold by NAPA.

https://www.napaonline.com/en/p/NOS21771?interchange=1

http://www.gmcmhphotos.com/photos/general-pictures/p45146-rear-bogy-seal.html

J.R. Wright
GMC Great Laker
GMC Eastern States
GMCMHI
TZE Zone Restorations
78 Buskirk Custom 30' Stretch
75 Avion (Under going Frame up Restoration)

> Ken,
> I opened a can of worms for myself when I took a look at someone's coach
> after the GMCMI. There was too much play in the passenger rearmost wheel,
> and that lead to discovering a loose bearing cup, broken brake shoes, an
> out of round drum on it's last legs, etc.
>
> Trying to put it back together, I'm trying to locate seals that pass the
> 1/4" test and after hitting several auto parts stores and opening a dozen or
> more boxes from several different brands, found that none of them passed,
> or were even that close. From the drawing in the manual it appears as you
> say, that there's no way the metal could contact the bearing. So where
> did the 1/4" test come from? Does it matter?
>
> Richard V.
>

> > John,
> >
> > IIRC, you're thinking of the front wheel bearing seal. From the drawing
> I
> > posted, it appears virtually impossible for the metal to touch the
> > bearing. But the rubber is separated from it only by about the distance
> > the seal should be left proud of the hub.
> >
> > https://drive.google.com/file/d/0B3XquSIYjDleenNDM1BHQlNHa1E/
> > view?usp=sharing
> >
> > Ken H.
> >
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> --
> '77 Birchaven TZE...777
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
JR,

At last falls GMCMI Convention in Elkhart, Dave showed me that the Chicago Rawhide / SKF 21771 had problems as well which is why he
found a source that was OK and produced the installation tool.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of John Wright
Sent: Friday, April 20, 2018 10:50 AM
To: gmclist
Subject: Re: [GMCnet] NAPA SKF-21771 rear bearing seal fails the 0.25" test

This issue was originally brought up by Dave Lenzi at the Fall 2010 DuQuoin
Convention where he had discovered several sets of rear bearings had an
issue with metal in the grease. Dave said there were 2 manufactures that
were OK. They are the Chicago Rawhide 3857731 and the SKF 21771. The SKF
is sold by NAPA.

https://www.napaonline.com/en/p/NOS21771?interchange=1

http://www.gmcmhphotos.com/photos/general-pictures/p45146-rear-bogy-seal.html

J.R. Wright
GMC Great Laker
GMC Eastern States
GMCMHI
TZE Zone Restorations
78 Buskirk Custom 30' Stretch
75 Avion (Under going Frame up Restoration)
 
Read here
http://bdub.net/gmcmotorhome.info/front.html

> JR,
>
> At last falls GMCMI Convention in Elkhart, Dave showed me that the Chicago
> Rawhide / SKF 21771 had problems as well which is why he
> found a source that was OK and produced the installation tool.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces] On Behalf Of John
> Wright
> Sent: Friday, April 20, 2018 10:50 AM
> To: gmclist
> Subject: Re: [GMCnet] NAPA SKF-21771 rear bearing seal fails the 0.25" test
>
> This issue was originally brought up by Dave Lenzi at the Fall 2010 DuQuoin
> Convention where he had discovered several sets of rear bearings had an
> issue with metal in the grease. Dave said there were 2 manufactures that
> were OK. They are the Chicago Rawhide 3857731 and the SKF 21771. The SKF
> is sold by NAPA.
>
> https://www.napaonline.com/en/p/NOS21771?interchange=1
>
>
> http://www.gmcmhphotos.com/photos/general-pictures/p45146-rear-bogy-seal.html
>
> J.R. Wright
> GMC Great Laker
> GMC Eastern States
> GMCMHI
> TZE Zone Restorations
> 78 Buskirk Custom 30' Stretch
> 75 Avion (Under going Frame up Restoration)
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
> Bruce,
>
> It should be noted that Dave found a supplier that provided seals that met HIS requirements THEN manufactured the tool to install
> them.
>
> The tool may or may not work with Chicago Rawhide / SKF or seals made by other manufacturers.
>
> Regards,
> Rob M.

Rob,
I haven't found an SKF seal that passes the 1/4" test, and I'm beginning to feel that it's a fool's errand trying to find one.

Would I be off-base assuming that one could measure the clearance of the rubber seal and simply add the difference that it's short to the spec for how
proud the seal sits? That is, if instead of .250" clearance under the rubber there's only .220" could I add the .030" difference to the spec'd .025"
to .045" proud seal set? ie, set the seal .055" to .075" proud?

Is this simply a measure the seal and modify the depth of set situation? That would make my life simpler and piss off far fewer auto parts people!

Thanks.

Richard
--
'77 Birchaven TZE...777
 
> I will call SKF tomorrow and get a dim drawing. Pass it along to the group. It is possible that SKF changed their internal spacing, as all the
> information in their seal catalog describes only applications where the seal is treated as a stand alone assembly, and not as a part (of a larger
> assembly). I'll turn a few seal installation tools, this weekend.

Rich,
I called SKF yesterday and the tech rep, while helpful, was unable to provide information on their seal's designed clearance, or a measured drawing,
so there's no way of knowing if recent SKF seals' failure to meet our clearance criteria is by design.

If you could get more information from SKF I'd love to see a dimensioned drawing.

Richard

--
'77 Birchaven TZE...777
 
I have noticed quite a bit of difference in the shoulders on different
spindles. Some protrude towards the threaded end more than others do. That
would place the shoulder close to the seal in some situations. And would be
the reason for interference in some situations.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> > I will call SKF tomorrow and get a dim drawing. Pass it along to the
> group. It is possible that SKF changed their internal spacing, as all the
> > information in their seal catalog describes only applications where the
> seal is treated as a stand alone assembly, and not as a part (of a larger
> > assembly). I'll turn a few seal installation tools, this weekend.
>
>
> Rich,
> I called SKF yesterday and the tech rep, while helpful, was unable to
> provide information on their seal's designed clearance, or a measured
> drawing,
> so there's no way of knowing if recent SKF seals' failure to meet our
> clearance criteria is by design.
>
> If you could get more information from SKF I'd love to see a dimensioned
> drawing.
>
> Richard
>
> --
> '77 Birchaven TZE...777
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Richard,

Review this drawing:

http://www.gmcmhphotos.com/photos/skf-21771-rear-seal-fails-test/p63893-rear-axle-seal.html

Note the position of the seal on the spindle. The problem arises when the seal comes in contact with the inner race of the bearing.

I guess you could set the seal to 0.055 to 0.070 proud and then coat it with grease and put the hub on until the inner bearing seats
on the spindle, then pull it straight off.

Look at the spindle and see where the grease is on the spindle.

I don't know if this will work or not but it's the only way I could come up with to see where the seal rode.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Richard
Sent: Friday, April 20, 2018 2:49 PM
To: gmclist
Subject: Re: [GMCnet] NAPA SKF-21771 rear bearing seal fails the 0.25" test

Rob,

I haven't found an SKF seal that passes the 1/4" test, and I'm beginning to feel that it's a fool's errand trying to find one.

Would I be off-base assuming that one could measure the clearance of the rubber seal and simply add the difference that it's short
to the spec for how proud the seal sits? That is, if instead of .250" clearance under the rubber there's only .220" could I add the
.030" difference to the spec'd .025" to .045" proud seal set? ie, set the seal .055" to .075" proud?

Is this simply a measure the seal and modify the depth of set situation? That would make my life simpler and piss off far fewer
auto parts people!

Thanks.
Richard
 
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