Bearing failures

[thomas g. warner]

I think that this is an interesting post at least to me and supports my
earlier opinion relative to disasterous failures, incorrect parts etc.

If the wheel bearings were indeed from Gateway (.006 clearance) than if it
were my coach, I would ask them to please pay for the money and parts to
repair it after this failure. Gateway says they only sell parts approved
for the GMC motorhome. Bearings with .006" axial clearance are NOT
appropriate for the GMC motorhome, since GM says that at least a clearance
of .095" are needed, and clearances less than this can cause just the
failure that you have described.

Same with the General load range D tires and a duplicate of my experience
with D range tires.

Am hoping for more posts like this so we can get to the root of the problem.
I would hate to have this happen to my coach.

Arch you are finally getting somewhere. Congradulations.

>HEY, ARCH.....
>
>Ready??
>Returning from a mini-rally at Gulf Shores, AL yesterday, within 20 miles of
>home on US Hwy 49 northbound @ 65 mph, no shimmy, no noise, no warning,..right
>front wheel and hub broke off, huge thick white cloud of smoke streaming
>behind coach so thick it appeared my rear window was painted - could not see
>behind me - took well over 1/4 mile to stop, kept her on concrete as long as
>possible before letting her hit asphalt shoulder to grind and plow to a stop.
>Today's shopping list includes hub, knuckle, bearings, seals, rotor (Ken Thoma
>is a Godsend), calipers, drive axle shaft, lower ball joint, CV joint & boot,
>brake line, lower A-frame, tie rod end, misc bolts, boots, etc., then get to
>do some fiberglass work and re-paint.
>
>Bearings from Gateway installed 11/29/97, by experienced GMC mechanic using
>Ken Thoma tools, less than 7,000 miles, best grease, .006 clearance, tight as
>new when checked 7 days ago.
>
>Co-pilot praised my ability to hold JimiSue steady - told her I'd practiced it
>a thousand times in my sleep over the years.
>
>Related similar scenario to one of our fabled GMC experts about a year ago,
>and he told me it couldn't happen.
>
>Coming out of New Orleans in 1982 in my 1977 Royale with a coach full of kids
>after a game at the Superdome, 70 mph on I-10, heavy traffic all lanes,..no
>shimmy, no noise, no warning, left front wheel flew off, crossed median and
>into heavy oncoming traffic, took well over 1/4 mile to stop. Damage about the
>same, but more extensive body work.
>
>1979 - 20 miles out of Starkville, MS 11:00 PM, inbound to football game @
>MSU. Noise, vibration, shimmy, pulling,... wheel stayed on, limped into town,
>found local mechanic to hammer on new bearings on Saturday to get back home
>where local GMC dealer from whom I had bought the coach new could hammer on a
>new set just to set up another set of failures.
>
>And GM was still advising to service the bearings every 50,000 miles (whether
>they needed it or not).
>
>And then there was the experience of having the coach suddenly fill with smoke
>from a blown oil line @ 2:00 AM just as I entered New Orleans, but that's
>another thread, and not the only one of those. And the overly long brake line
>being rubbed in two by the transaxle (power boosters and vacuum tanks don't
>help a lot then), etc.
>Or those great General tires they came with that I couldn't wear out for
>blowing out.
>
>Oh, Lord, it's hard to be humble
>When you travel the GMC way.
>Can't wait to see her each morning
>She gets better looking each day.
>To own one is to love one
>What a heck of a way to roam.
>Oh, Lord, it's hard to be humble
>In our GMC MotorHome.
>
>Oh, yes, we used to have money
>For travel to far away lands
>But now we spend all our paychecks
>For air bags, bearings, and fans.
>To own one is to fix one
>and pay off many a loan
>But, Lordy, we still love her
>Our GMC MotorHome.
>
>(Plagerized from Don Perry, GMC Cascaders)
>
>Lanier
>'73 ???26'
>Jxn,MS
>FMCA # 37894
>DixieLanders
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[bdub]

>HEY, ARCH.....
>
>Ready??
>Returning from a mini-rally at Gulf Shores, AL yesterday, within 20 miles of
>home on US Hwy 49 northbound @ 65 mph, no shimmy, no noise, no warning,..right
>front wheel and hub broke off, huge thick white cloud of smoke streaming
>behind coach so thick it appeared my rear window was painted - could not see

- -------snip--------- I can't stand to read it again! ...........

>Oh, Lord, it's hard to be humble
>When you travel the GMC way.
>Can't wait to see her each morning
>She gets better looking each day.
>To own one is to love one
>What a heck of a way to roam.
>Oh, Lord, it's hard to be humble
>In our GMC MotorHome.
>
>Oh, yes, we used to have money
>For travel to far away lands
>But now we spend all our paychecks
>For air bags, bearings, and fans.
>To own one is to fix one
>and pay off many a loan
>But, Lordy, we still love her
>Our GMC MotorHome.
>
>(Plagerized from Don Perry, GMC Cascaders)
>
>Lanier
>'73 ???26'
>Jxn,MS
>FMCA # 37894
>DixieLanders

hahahahaa boohooobooohoooo

Neat little jingle! I'm laughin and cryin at the same time! I ain't gonna
let my wife see this. I'm having second thoughts and your scaring me!

********************************************************************
bdub Billy Massey
Life in th' Slow Lane bmassey
Lake Brownwood, Texas http://www.web-access.net/~bmassey/
--'76 Palm Beach-- http://wwp.mirabilis.com/202333
********************************************************************

 

[chuck will]

You omake my life see like it has been "DULL" to "Nothing" Chuck

> HEY, ARCH.....
>
> Ready??
> Returning from a mini-rally at Gulf Shores, AL yesterday, within 20 miles of
> home on US Hwy 49 northbound @ 65 mph, no shimmy, no noise, no warning,..right
> front wheel and hub broke off, huge thick white cloud of smoke streaming
> behind coach so thick it appeared my rear window was painted - could not see
> behind me - took well over 1/4 mile to stop, kept her on concrete as long as
> possible before letting her hit asphalt shoulder to grind and plow to a stop.
> Today's shopping list includes hub, knuckle, bearings, seals, rotor (Ken Thoma
> is a Godsend), calipers, drive axle shaft, lower ball joint, CV joint & boot,
> brake line, lower A-frame, tie rod end, misc bolts, boots, etc., then get to
> do some fiberglass work and re-paint.
>
> Bearings from Gateway installed 11/29/97, by experienced GMC mechanic using
> Ken Thoma tools, less than 7,000 miles, best grease, .006 clearance, tight as
> new when checked 7 days ago.
>
> Co-pilot praised my ability to hold JimiSue steady - told her I'd practiced it
> a thousand times in my sleep over the years.
>
> Related similar scenario to one of our fabled GMC experts about a year ago,
> and he told me it couldn't happen.
>
> Coming out of New Orleans in 1982 in my 1977 Royale with a coach full of kids
> after a game at the Superdome, 70 mph on I-10, heavy traffic all lanes,..no
> shimmy, no noise, no warning, left front wheel flew off, crossed median and
> into heavy oncoming traffic, took well over 1/4 mile to stop. Damage about the
> same, but more extensive body work.
>
> 1979 - 20 miles out of Starkville, MS 11:00 PM, inbound to football game @
> MSU. Noise, vibration, shimmy, pulling,... wheel stayed on, limped into town,
> found local mechanic to hammer on new bearings on Saturday to get back home
> where local GMC dealer from whom I had bought the coach new could hammer on a
> new set just to set up another set of failures.
>
> And GM was still advising to service the bearings every 50,000 miles (whether
> they needed it or not).
>
> And then there was the experience of having the coach suddenly fill with smoke
> from a blown oil line @ 2:00 AM just as I entered New Orleans, but that's
> another thread, and not the only one of those. And the overly long brake line
> being rubbed in two by the transaxle (power boosters and vacuum tanks don't
> help a lot then), etc.
> Or those great General tires they came with that I couldn't wear out for
> blowing out.
>
> Oh, Lord, it's hard to be humble
> When you travel the GMC way.
> Can't wait to see her each morning
> She gets better looking each day.
> To own one is to love one
> What a heck of a way to roam.
> Oh, Lord, it's hard to be humble
> In our GMC MotorHome.
>
> Oh, yes, we used to have money
> For travel to far away lands
> But now we spend all our paychecks
> For air bags, bearings, and fans.
> To own one is to fix one
> and pay off many a loan
> But, Lordy, we still love her
> Our GMC MotorHome.
>
> (Plagerized from Don Perry, GMC Cascaders)
>
> Lanier
> '73 ???26'
> Jxn,MS
> FMCA # 37894
> DixieLanders

 

[chuck will]

I use "E" rated tires because of an astute sales person in an AAFFES gas station on
Vandenberg. The little advisory on the glove compartment door says use "D" tires
and inflate to 65 PSI. Chuck

> I think that this is an interesting post at least to me and supports my
> earlier opinion relative to disasterous failures, incorrect parts etc.
>
> If the wheel bearings were indeed from Gateway (.006 clearance) than if it
> were my coach, I would ask them to please pay for the money and parts to
> repair it after this failure. Gateway says they only sell parts approved
> for the GMC motorhome. Bearings with .006" axial clearance are NOT
> appropriate for the GMC motorhome, since GM says that at least a clearance
> of .095" are needed, and clearances less than this can cause just the
> failure that you have described.
>
> Same with the General load range D tires and a duplicate of my experience
> with D range tires.
>
> Am hoping for more posts like this so we can get to the root of the problem.
> I would hate to have this happen to my coach.
>
> Arch you are finally getting somewhere. Congradulations.
>

> >HEY, ARCH.....
> >
> >Ready??
> >Returning from a mini-rally at Gulf Shores, AL yesterday, within 20 miles of
> >home on US Hwy 49 northbound @ 65 mph, no shimmy, no noise, no warning,..right
> >front wheel and hub broke off, huge thick white cloud of smoke streaming
> >behind coach so thick it appeared my rear window was painted - could not see
> >behind me - took well over 1/4 mile to stop, kept her on concrete as long as
> >possible before letting her hit asphalt shoulder to grind and plow to a stop.
> >Today's shopping list includes hub, knuckle, bearings, seals, rotor (Ken Thoma
> >is a Godsend), calipers, drive axle shaft, lower ball joint, CV joint & boot,
> >brake line, lower A-frame, tie rod end, misc bolts, boots, etc., then get to
> >do some fiberglass work and re-paint.
> >
> >Bearings from Gateway installed 11/29/97, by experienced GMC mechanic using
> >Ken Thoma tools, less than 7,000 miles, best grease, .006 clearance, tight as
> >new when checked 7 days ago.
> >
> >Co-pilot praised my ability to hold JimiSue steady - told her I'd practiced it
> >a thousand times in my sleep over the years.
> >
> >Related similar scenario to one of our fabled GMC experts about a year ago,
> >and he told me it couldn't happen.
> >
> >Coming out of New Orleans in 1982 in my 1977 Royale with a coach full of kids
> >after a game at the Superdome, 70 mph on I-10, heavy traffic all lanes,..no
> >shimmy, no noise, no warning, left front wheel flew off, crossed median and
> >into heavy oncoming traffic, took well over 1/4 mile to stop. Damage about the
> >same, but more extensive body work.
> >
> >1979 - 20 miles out of Starkville, MS 11:00 PM, inbound to football game @
> >MSU. Noise, vibration, shimmy, pulling,... wheel stayed on, limped into town,
> >found local mechanic to hammer on new bearings on Saturday to get back home
> >where local GMC dealer from whom I had bought the coach new could hammer on a
> >new set just to set up another set of failures.
> >
> >And GM was still advising to service the bearings every 50,000 miles (whether
> >they needed it or not).
> >
> >And then there was the experience of having the coach suddenly fill with smoke
> >from a blown oil line @ 2:00 AM just as I entered New Orleans, but that's
> >another thread, and not the only one of those. And the overly long brake line
> >being rubbed in two by the transaxle (power boosters and vacuum tanks don't
> >help a lot then), etc.
> >Or those great General tires they came with that I couldn't wear out for
> >blowing out.
> >
> >Oh, Lord, it's hard to be humble
> >When you travel the GMC way.
> >Can't wait to see her each morning
> >She gets better looking each day.
> >To own one is to love one
> >What a heck of a way to roam.
> >Oh, Lord, it's hard to be humble
> >In our GMC MotorHome.
> >
> >Oh, yes, we used to have money
> >For travel to far away lands
> >But now we spend all our paychecks
> >For air bags, bearings, and fans.
> >To own one is to fix one
> >and pay off many a loan
> >But, Lordy, we still love her
> >Our GMC MotorHome.
> >
> >(Plagerized from Don Perry, GMC Cascaders)
> >
> >Lanier
> >'73 ???26'
> >Jxn,MS
> >FMCA # 37894
> >DixieLanders
> >
> >
> Tom & Marg Warner
> Vernon Center NY
> 1976 palmbeach

 

[ted schurman]

>(snipped so you won't have to read the rest Lanier)
> Bearings from Gateway installed 11/29/97, by experienced GMC mechanic using
> Ken Thoma tools, less than 7,000 miles, best grease, .006 clearance, tight as
> new when checked 7 days ago.
>

What exactly failed? Do you know ? When you say it was still tight.
I assume you mean no wheel movement not that the .006 clearance was OK.
Had you ever felt the axle to see if it was running hot?

To the rest of you, would that be a meaningful test ?

Ted schurman
73 Glacier VA

 

[chuck will]

Does Ken Thoma have an email address? I need some information from a pro on
front ends. It is time to do the hubs/knuckles or a complete assembly again.
Chuck, 78 Eleganza II, Lompoc, CA

> Lanier
>
> Wow what can I say. On this last breakdown----was it a bearing failure
> or hub failure? I mean is the axle all blue from heat or just cracked off.
> How much does the front of your coach weigh. How many batteries
> do you have up front? Are your air conditioners still in the stock
> position? Do you have any unusual weight up front?
>
> I am sorry to ask so many questions but I honestly want to understand
> this "bearing thing." I am asking to learn not to criticize you in any way.
>
> Take Care
> Arch 76 GB IL
>
> >
> > Ready??
> > Returning from a mini-rally at Gulf Shores, AL yesterday, within 20 miles
> of
> > home on US Hwy 49 northbound @ 65 mph, no shimmy, no noise, no warning,..
> > right
> > front wheel and hub broke off, huge thick white cloud of smoke streaming
> > behind coach so thick it appeared my rear window was painted - could not
> see
> > behind me - took well over 1/4 mile to stop, kept her on concrete as long
> as
> > possible before letting her hit asphalt shoulder to grind and plow to a
> stop.
> >
> > Today's shopping list includes hub, knuckle, bearings, seals, rotor (Ken
> > Thoma
> > is a Godsend), calipers, drive axle shaft, lower ball joint, CV joint &
> boot,
> >
> > brake line, lower A-frame, tie rod end, misc bolts, boots, etc., then get
> to
> > do some fiberglass work and re-paint.
> >

 

[thomas g. warner]

We seem to be getting somewhere on bearing problems but there still seems to
be a lot of disagreement on the correct way to determine the proper bearing
and how to install them. I think that this is because most do not understand
the problems associated with the hubs, kuckles and bearings on various
coaches. They are not all the same! Remember all hubs, knuckles, and
bearings have manufacturing tolerances. A bearing set with a clearance of
.004" that has ran for years with no problems may instantly seize up and
cause a disasterous failure in another coach. That is why we have to be very
careful when giving advice to others on our experiences in this area. It
could be dangerous.

I would be interested in where you got the information " but from what I've
been told by the Guru's, thetolerance/clearance of the bearings originally
supplied by GM varied from .002 to .014, whereas the optimum is .006 (.004
is a little tight for the heat buildup, and .008 gives a little wobble right
off the bat)"?

Everything you have stated is just the opposite to what I have found by my
research and been told by others. If bearings with an axial clearance of
.008 caused your front wheels to wobble there might have been something else
wrong with your hubs or knuckles, or axel nut torque, or the dimensions of
your hubs or knuckles may be out of tolerance. On another coach these
bearings of .008" MIGHT have worked.

I would like to analyze the problem of installing front wheel bearings a
little more closely so we all are can hopefully come to a common
understanding and quit the worrying of whether we are doing it right, and if
they will fall off in the middle of our trip.

1. The front hub should not be tapered and should uniformly measure from
2.0015" to 2.0020" from top to bottom.
If yours do not come within these tolerances you MUST replace them.

2. The inside of the knuckle should measure from 3.2510" to 3.2525" with no
ridges or gouges in it, and out of round not to exceed .0015". This
dimension can only be measured accurately with a three-point cylinder bore
measuring tool.

3. The bearings have an inside and outside tolerance depending on manufacturer.

If you put a bearing with an axial clearance of .004" on a hub of dimension
2.0020" and fit that combination into a knuckle of inside dimension of
3.2510", it will almost certainly seize when run. Why? Because when you
press the bearing with a minimum possible inside dimension and maximum
outside dimension, over a hub with maximum tolerance into a knuckle with
minimum tolerance there is no axial play left. The bearing will in all
likelihood seize.

If you have the correct equipment and understand all of the factors that
come into play when assebling these components you may get away with
installing bearings with .002" to .0075" of clearance on your coach. The
question is how many owners have the expertise, and know how to properly
allow for the various tolerances?

To be sure that everyting works correctly and is safe, General Motors
engineers redesigned the front wheel bearings with a uniform .095" of axial
clearance and 20% more load bearing capacity. These bearings will work
under the varying conditions I have described, as long as your hubs and
knuckles are within tolerances.

Does anyone have information that contradicts what I have said. This is a
subject of much concern to all GMC owners and really needs to be understood
by all.



>In a message dated 98-11-11 23:45:01 EST, you write:
>

>>
>> > Lanier
>> >
>> > Wow what can I say. On this last breakdown----was it a bearing failure
>> > or hub failure? I mean is the axle all blue from heat or just cracked
>off.
>> >
>ARCH, et al;
>I'm not really in a position yet to lay blame, but I fully intend to be before
>it's over. On the other occasions I let the parts get away from me and didn't
>really realize the significance, relying on GM in its infinite wisdom. It was
>a whole different world back then - we didn't dare move a button on one of
>these things, 'cause that's the way GM built them. I blew umpteen General
>tires before finally throwing the things away and getting Michelins after
>having one blow off my RR skirt, cargo door, and all fiberglass in between on
>US 90 @ Gulfport, just after having delivered about 25 - 30 kids to a church
>camp after the church bus broke down just outside Jackson (less than 60 days
>later, GM & General admitted the error and recalled the tires, but mine were
>already gone).
>I never made it to Engineering School and never could figure out how to
>operate a slide rule, but from what I've been told by the Guru's, the
>tolerance/clearance of the bearings originally supplied by GM varied from .002
>to .014, whereas the optimum is .006 (.004 is a little tight for the heat
>buildup, and .008 gives a little wobble right off the bat).
>The possible causes that I've heard include everything from CV joint heat to
>quality of grease, so I would like to have a metallurgist look at these pieces
>and try to determine the culprit.
>The wheels were examined just before I left Jackson and were tight -
>absolutely no play @ 6/12 or 3/9. The rear ones were at varying degrees of
>slack and were all tightened. All bearing were installed/serviced at the same
>time. I have 2 batteries up front and the roof A/C is in its original
>location. I have added a Winegard TV antenna, SolarMaxx fan, and awning, and
>the inside weight is what I would call normal. I have quite a few tools under
>the couch, but they're all on the other side. The dinette has been replaced by
>2 lighter chairs.
>Bobby Moore gave me the name and # of someone making a 1000` grease, and I'm
>going to dig it up and call today.
>That's all I know right now, and I guess I don't understand everything I do
>know.
>Thanks for the interest.
>Lanier
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[gary miller]

Tom,
Your analysis makes sense to me and adequately explains why some have problems and
others do not. Question: When did GM redesign the front wheel bearings?? Did
production coaches have the redesign incorporated???
Gary
'77 Kingsley
North Bend, Oregon Coast

> We seem to be getting somewhere on bearing problems but there still seems to
> be a lot of disagreement on the correct way to determine the proper bearing
> and how to install them. I think that this is because most do not understand
> the problems associated with the hubs, kuckles and bearings on various
> coaches. They are not all the same! Remember all hubs, knuckles, and
> bearings have manufacturing tolerances. A bearing set with a clearance of
> .004" that has ran for years with no problems may instantly seize up and
> cause a disasterous failure in another coach. That is why we have to be very
> careful when giving advice to others on our experiences in this area. It
> could be dangerous.
>
> I would be interested in where you got the information " but from what I've
> been told by the Guru's, thetolerance/clearance of the bearings originally
> supplied by GM varied from .002 to .014, whereas the optimum is .006 (.004
> is a little tight for the heat buildup, and .008 gives a little wobble right
> off the bat)"?
>
> Everything you have stated is just the opposite to what I have found by my
> research and been told by others. If bearings with an axial clearance of
> .008 caused your front wheels to wobble there might have been something else
> wrong with your hubs or knuckles, or axel nut torque, or the dimensions of
> your hubs or knuckles may be out of tolerance. On another coach these
> bearings of .008" MIGHT have worked.
>
> I would like to analyze the problem of installing front wheel bearings a
> little more closely so we all are can hopefully come to a common
> understanding and quit the worrying of whether we are doing it right, and if
> they will fall off in the middle of our trip.
>
> 1. The front hub should not be tapered and should uniformly measure from
> 2.0015" to 2.0020" from top to bottom.
> If yours do not come within these tolerances you MUST replace them.
>
> 2. The inside of the knuckle should measure from 3.2510" to 3.2525" with no
> ridges or gouges in it, and out of round not to exceed .0015". This
> dimension can only be measured accurately with a three-point cylinder bore
> measuring tool.
>
> 3. The bearings have an inside and outside tolerance depending on manufacturer.
>
> If you put a bearing with an axial clearance of .004" on a hub of dimension
> 2.0020" and fit that combination into a knuckle of inside dimension of
> 3.2510", it will almost certainly seize when run. Why? Because when you
> press the bearing with a minimum possible inside dimension and maximum
> outside dimension, over a hub with maximum tolerance into a knuckle with
> minimum tolerance there is no axial play left. The bearing will in all
> likelihood seize.
>
> If you have the correct equipment and understand all of the factors that
> come into play when assebling these components you may get away with
> installing bearings with .002" to .0075" of clearance on your coach. The
> question is how many owners have the expertise, and know how to properly
> allow for the various tolerances?
>
> To be sure that everyting works correctly and is safe, General Motors
> engineers redesigned the front wheel bearings with a uniform .095" of axial
> clearance and 20% more load bearing capacity. These bearings will work
> under the varying conditions I have described, as long as your hubs and
> knuckles are within tolerances.
>
> Does anyone have information that contradicts what I have said. This is a
> subject of much concern to all GMC owners and really needs to be understood
> by all.
>
>
>

> >In a message dated 98-11-11 23:45:01 EST, you write:
> >

> >>
> >> > Lanier
> >> >
> >> > Wow what can I say. On this last breakdown----was it a bearing failure
> >> > or hub failure? I mean is the axle all blue from heat or just cracked
> >off.
> >> >
> >ARCH, et al;
> >I'm not really in a position yet to lay blame, but I fully intend to be before
> >it's over. On the other occasions I let the parts get away from me and didn't
> >really realize the significance, relying on GM in its infinite wisdom. It was
> >a whole different world back then - we didn't dare move a button on one of
> >these things, 'cause that's the way GM built them. I blew umpteen General
> >tires before finally throwing the things away and getting Michelins after
> >having one blow off my RR skirt, cargo door, and all fiberglass in between on
> >US 90 @ Gulfport, just after having delivered about 25 - 30 kids to a church
> >camp after the church bus broke down just outside Jackson (less than 60 days
> >later, GM & General admitted the error and recalled the tires, but mine were
> >already gone).
> >I never made it to Engineering School and never could figure out how to
> >operate a slide rule, but from what I've been told by the Guru's, the
> >tolerance/clearance of the bearings originally supplied by GM varied from .002
> >to .014, whereas the optimum is .006 (.004 is a little tight for the heat
> >buildup, and .008 gives a little wobble right off the bat).
> >The possible causes that I've heard include everything from CV joint heat to
> >quality of grease, so I would like to have a metallurgist look at these pieces
> >and try to determine the culprit.
> >The wheels were examined just before I left Jackson and were tight -
> >absolutely no play @ 6/12 or 3/9. The rear ones were at varying degrees of
> >slack and were all tightened. All bearing were installed/serviced at the same
> >time. I have 2 batteries up front and the roof A/C is in its original
> >location. I have added a Winegard TV antenna, SolarMaxx fan, and awning, and
> >the inside weight is what I would call normal. I have quite a few tools under
> >the couch, but they're all on the other side. The dinette has been replaced by
> >2 lighter chairs.
> >Bobby Moore gave me the name and # of someone making a 1000` grease, and I'm
> >going to dig it up and call today.
> >That's all I know right now, and I guess I don't understand everything I do
> >know.
> >Thanks for the interest.
> >Lanier
> >
> >
> Tom & Marg Warner
> Vernon Center NY
> 1976 palmbeach

 

[patrick flowers]

>
> I'm not really in a position yet to lay blame, but I fully intend to
> be before it's over.

Thanks for sharing the experience Lanier. Please keep us updated as
this unfolds.

> Bobby Moore gave me the name and # of someone making a 1000` grease,
> and I'm going to dig it up and call today.

Is that supposed to be 1000 deg. grease? IIRC, Mobil1's drop point is
600 deg. and Redline CV-2 is supposedly 900 deg. Anything above 500
deg. may be irrelevant as steel begins to lose strength at that point.

> That's all I know right now, and I guess I don't understand
> everything I do know.

Aye, I know the feeling,
Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[patrick flowers]

>
> We seem to be getting somewhere on bearing problems but there still
> seems to be a lot of disagreement on the correct way to determine the
> proper bearing and how to install them.

 

[patrick flowers]

>
> Had the current bearings been simply installed without regard to, or
> inspection of, the other parts you mentioned, I could grin and bear
> it. My knuckles, hubs, lower ball joints, CV joints, etc. were all
> replaced with either new, or supposedly machined to tolerance, parts
> last November when the bearings were replaced, all at a cost in
> excess of $3,600 (as the result of a hard-headed tire-changer not
> listening to simple instructions). We did not get the parts from a
> junk yard, or from Joe's Auto Zonia, we did not measure tolerances
> with a yard stick, and I know you can't snuggly put a square peg in
> a round hole. Had the job not been done right, and with the right
> parts, I doubt that I would have made it 7,000 miles pulling a car
> through mountains in extremely hot weather.

Lanier, the only thing that makes a bell ring in the above is the
possibility that the tolerances on the new parts were too tight for .006
unassembled axial clearance bearings. Why it would have waited 7,000
miles to manifest itself, who knows.

> That is the reason I intend to hire a pro to determine the cause;

That's the ticket. We can all sit here and speculate electronically til
the cows come home, but you couldn't buy a cup of coffee with the
results. I know of a few good testing labs if you're interested.

> I'm not presently satisfied that the fault is the bearings. Could an
> overheated, dry CV joint have created enough heat to dissipate the
> bearing grease and destroy the bearings??? I seem to remember a
> recent thread about the brake calipers hanging up and creating
> excessive heat on the bearings???

Yeah, it's possible, but either a stuck caliper or bad CV joint should
make themselves known prior to "automatic disassembly" of the hub.
Might just be bad luck, but get a real expert's opinion before you try
to take anything we say to the bank.

Thanks again!
Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[patrick flowers]

>
> Are NEW knuckles available? Larry Nelson, PB-75, Springfield, MO

Yep, from Cinnabar. $250 each.

Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[thomas g. warner]

The new bearing sets went into production in early 1991, but were never
retrofitted on GMC coaches as a recall. General Motors Service Parts
Operations (GMSPO) did the study on the bearings around the 1989 time
frame. The previous GM bearing part # 745526 was actually made for GM by
at least 4 companies each with different axial clearances. The bearings
in order of least to most axial clearance were: Bower .004", Timken .006"
and New Departure Hyatt .015"

During the GM tests it was found that a bearing set with a minimum
inside diameter pressed onto a hub of maximum allowable diameter, would
reduce axial clearance by as much as .007". In order for the bearings to
work without seizure they need at least .002 to .003" of assembled axial
clearance. They therefore concluded that to be safe in a worse case
scenario, the correct bearing set should have an unassembled axial
clearance of .095" which equates to .007" for possible reduction of the
clearance in the worse case plus '002 to .003" of running clearance.

This new bearing set is part # 12351677. It has a 20% higher load
carrying capacity and .095" of axial clearance.

So my advise is to use the correct part # 12351677 bearing unless you
have the capability to properly size the bearing axial clearance to the
hub diameter and knuckle.

>Tom,
>Your analysis makes sense to me and adequately explains why some have
problems and
>others do not. Question: When did GM redesign the front wheel bearings?? Did
>production coaches have the redesign incorporated???
>Gary
>'77 Kingsley
>North Bend, Oregon Coast

 

[thomas g. warner]

Rick what a tattletale you are! Just when I was trying to impress everyone
with my knowledge. I have that publication you referenced and several more.
I also talked to Wes Cauglin for good measure. I am convinced that proper
bearings, hubs and knuckles installed with mobil 1 grease will b ea bullet
proof combination.

>
>> I would like to analyze the problem of installing front wheel bearings a
>> little more closely so we all are can hopefully come to a common
>> understanding and quit the worrying.....................
>
>Tom,
> Thank you for the clearest and most comprehensive/factual discussion of
>this critical topic we've seen yet. From all I've read and heard you are
>right on the money. The RIGHT bearings PROPERLY installed in UNDAMAGED
>knuckles and hubs will rarely if ever fail suddenly within their 25,000 mile
>service interval. Apparently even some bearings supplied by GM from ~1989
>-1991 were not a proper fit and caused failures. (Insufficient axial
>clearance).
> For those who want further confirmation, technical details, and history on
>this matter, see the GMC Motorhome News, issue #8, June 1996, pp 7 - 11.
>(Published by Cinnabar.) I for one will only use genuine GM bearing sets part
># 12351677, (manufactured I believe by Timken, but quality/tolerance selected
>from the best of their production). They cost little more than the others
>and I have confidence they will fit and last.
> BTW, in younger years, working on various clunkers for myself and friends
>(but not customers), I would often "take a chance" with a slightly worn
>bearing housing or shaft, upsetting the metal with punch marks and/or using
>LocTite bearing mount compound to hold things in place. NOT ON THE GMC! When
>I discovered a worn Rt. frt. knuckle while replacing the bearings, I swallowed
>hard and dug up the $$$ to replace it with a NEW one. The GMC is in some ways
>like a big truck: very strong but unforgiving of sloppy maintennance or shoddy
>repairs, even when done unintentionally.
> Just my .02.
>
>Rick Staples
>'75 Eleganza, Louisville, CO
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

In my experience a CV joint would not cause this kind of problem. The outer
CV joint actually moves in a very small radial path when driving on a smooth
road. Even on very worn ones you seldom hear anything uless turning in a
tight turn at low speeds. That is how you check them first on the coach by
the way. Get in a large parking lot and turn in a tight circle to the left
and than to the right and listen for a series of clicks indicating the balls
are catching in the races.

Again it is possible that the brakes could hang up and cause the bearings to
get very hot but again not very likely. You would most certainly see the
smoke from the pads first.

I believe that your bearings were installed incorrectly. If they were
installed without checking the clearances of the hubs and knuckles first,
than they were installed incorrectly. Plain and simple.

You would be surprised how many professional mechanics do it wrong! They use
the wrong tools, parts and have no knowledge of the GMC motorhome.

If I were you I would be asking the people that installed those bearings,
hubs and knuckles some serious questions, like I would like my money back.
We should no longer tolerate this kind of repairs.

The importance of this BB site is that everyone can learn how to do it
correctly. We have a tremendous amount of knowledge here. Even if you do
not do the work yourself, you can have the printed guidelines to give to the
mechanic. This is the way I want this repair done, this is how much it
should cost. Can you do it,have you got the correct tools to do the repair,
can you get the correct parts, and what is your cost? If he starts to get
off the subject, or starts to hedge, go some where else until you find a
mechanic that will.

>In a message dated 98-11-12 09:33:06 EST, you write:
>
>>
>> I would be interested in where you got the information " but from what I've
>> been told by the Guru's, thetolerance/clearance of the bearings originally
>> supplied by GM varied from .002 to .014, whereas the optimum is .006 (.004
>> is a little tight for the heat buildup, and .008 gives a little wobble
>right
>> off the bat)"?
>>
>TOM:::
>
>As I said, "I may not understand everything I know about this subject". I was
>relating an experience, not attempting to give technical advice or tell
>anybody how anything should be done. I'm not an engineer, not a mechanic, and
>not even a very good parts-changer, but I'm learning. My sources of
>information include Wes Coughlin (whom I believe to be the one who told me
>last year that he had never heard of a wheel coming off as a result of bearing
>failure **DISCLAIMER**), Bob Hendershot @ Gateway, and Ken Thoma of Texas.
>
>My previous bearing failures could, and probably should, be attributed to some
>of the items you mentioned, but that coach was new and GM did the bearings,
>hubs, knuckles, etc. at the factory and they hadn't been touched. I know why
>the one a year ago happened - they were simply hammered in after I tried my
>hardest to explain the intracacies involved, took copies of the manuals, and
>arranged for them to borrow a set of the Thoma tools locally, and they still
>ignored the warnings ("all you have to do is slide 'em on there and tighten up
>the nut").
>
>Had the current bearings been simply installed without regard to, or
>inspection of, the other parts you mentioned, I could grin and bear it. My
>knuckles, hubs, lower ball joints, CV joints, etc. were all replaced with
>either new, or supposedly machined to tolerance, parts last November when the
>bearings were replaced, all at a cost in excess of $3,600 (as the result of
>a hard-headed tire-changer not listening to simple instructions). We did not
>get the parts from a junk yard, or from Joe's Auto Zonia, we did not measure
>tolerances with a yard stick, and I know you can't snuggly put a square peg in
>a round hole. Had the job not been done right, and with the right parts, I
>doubt that I would have made it 7,000 miles pulling a car through mountains in
>extremely hot weather.
>
>As far as GM's technical edicts are concerned, they weren't brought down from
>the mount by Moses, and the wheel bearing specs can be placed right alongside
>quite a few other design flaws (pickup truck fuel tank placement, oil coolant
>lines, etc.).
>
>That is the reason I intend to hire a pro to determine the cause; I've enjoyed
>as much of this type expense and inconvenience as I can stand. On this re-
>build I've got Ken Thoma shipping me the entire package already put together,
>and I intend to go ahead and do the other side also.
>
>I'm not presently satisfied that the fault is the bearings. Could an
>overheated, dry CV joint have created enough heat to dissipate the bearing
>grease and destroy the bearings??? I seem to remember a recent thread about
>the brake calipers hanging up and creating excessive heat on the bearings???
>
>I don't know nuttin' else, but my noggin's open.
>Thanks for the shoulder.
>
>Lanier
>'73 et seq
>
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

Patrick I had the good fortune to have dinner tonight with a couple of other
GMC Heritage Cruisers members, Mr & Mrs Walter VonMatt and Mr & Mrs. Ray
Hill. Mr Hill has a 1978 Glenbrook that he bought brand new. Of course our
discussion (among the men) was repair and improvements to the coach. Walt
and I were talking up a storm telling each other of the things we had done.
Ray wasn't joining in and I thought he was just shy. After a few minutes my
curiosity got the best of me and I asked him what catastophic failures he
had since owing the coach (that was brave on my part since I figured there
goes the rest of the night).

Well! says Ray, I finally had to replace my engine this year in Oregon. Top
of the piston burned through from bad gas. Everything else is pretty much
original, transmission, final drive,air bags,rear bogie pins and bushings,
upper ball joints (lowers were replaced recently) interior, outside paint.

Aha! Had to be a very low mileage coach, I quickly thought to myself after
hearing of all of the disasters here. No! says Ray it has 178,000 miles on
it, been to every state, all over Canada and to Alaska 3 times. Did replace
the wheel bearings at 78,000 miles although they were still good, installed
Wallace hubs and now have 100,000 miles on them. Only time he was ever towed
was when engine blew. Wow!

Now we are getting somewhere! Sounds like the GMC motorhome that I think we
all have if we just maintain it right. Any more coaches out there like this?

>>
>> We seem to be getting somewhere on bearing problems but there still
>> seems to be a lot of disagreement on the correct way to determine the
>> proper bearing and how to install them.
>
>is definitely out of the ordinary. For this phenomenon to occur
>would probably require failure of the knuckle, seal retainer and stub
>axle, pretty much in that order.
>
>It will be very interesting to see what Lanier turns up as he digs into
>this.
>
>Patrick
>--
>Patrick Flowers
>Mailtoatri63
>
>The GMC Motorhome Page
>http://www.gmcmotorhome.com
>
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

Patrick I have to respectfully disagree with you about "We can all sit here
and speculate electronically til
>the cows come home, but you couldn't buy a cup of coffee with the >results".

We are not talking about rocket science here, nor are we talking about
speculation. We are talking about procedures that anyone reading this BB
can use to check their own bearings, hubs and knuckles. If we can't
accomplish and learn these types of repair procedures than what is the
intent of this BB? I thought we were trying to get to the truth and dispel
the myths as Arch says!

In my case I know a little bit about this subject and do indeed understand
both the principles and the common sense application of them. I am not only
a professional engineer but a certified metrologist (graduated from the
National Bureau of Standards in 1968). I worked in a Calibration laboratory
for a short time after. My hobby has been cars and anything mechanical for
over 40 years. I not only work on them but completely tear them apart as I
am doing with the 1976 Palmbeach that I now have. My guiding light has
always been, buy the best tools that you can afford, get the correct
technical literature that outlines the repair or maintenance, buy the
correct parts, and don't attempt anything that you do not have the special
tools for. It has always worked for me.

The procedures that I outlined are documented in Cinnabars technical
guidelines (GMC Motorhome news June 1996). They contain all of the
information that you will need to accomplish a safe, professional job. You
aren't going to get any better than that no matter who you talk to.

If lanier still has the parts take them to a machine shop and have them
measure the dimensions that I noted. They are either in or out of
tolerance. The same with the bearings, they are either the correct ones or not.

>>
>> Had the current bearings been simply installed without regard to, or
>> inspection of, the other parts you mentioned, I could grin and bear
>> it. My knuckles, hubs, lower ball joints, CV joints, etc. were all
>> replaced with either new, or supposedly machined to tolerance, parts
>> last November when the bearings were replaced, all at a cost in
>> excess of $3,600 (as the result of a hard-headed tire-changer not
>> listening to simple instructions). We did not get the parts from a
>> junk yard, or from Joe's Auto Zonia, we did not measure tolerances
>> with a yard stick, and I know you can't snuggly put a square peg in
>> a round hole. Had the job not been done right, and with the right
>> parts, I doubt that I would have made it 7,000 miles pulling a car
>> through mountains in extremely hot weather.
>
>Lanier, the only thing that makes a bell ring in the above is the
>possibility that the tolerances on the new parts were too tight for .006
>unassembled axial clearance bearings. Why it would have waited 7,000
>miles to manifest itself, who knows.
>
>> That is the reason I intend to hire a pro to determine the cause;
>
>That's the ticket. We can all sit here and speculate electronically til
>the cows come home, but you couldn't buy a cup of coffee with the
>results. I know of a few good testing labs if you're interested.
>
>> I'm not presently satisfied that the fault is the bearings. Could an
>> overheated, dry CV joint have created enough heat to dissipate the
>> bearing grease and destroy the bearings??? I seem to remember a
>> recent thread about the brake calipers hanging up and creating
>> excessive heat on the bearings???
>
>Yeah, it's possible, but either a stuck caliper or bad CV joint should
>make themselves known prior to "automatic disassembly" of the hub.
>Might just be bad luck, but get a real expert's opinion before you try
>to take anything we say to the bank.
>
>Thanks again!
>Patrick
>--
>Patrick Flowers
>Mailtoatri63
>
>The GMC Motorhome Page
>http://www.gmcmotorhome.com
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

I talked to Cinnabar yesterday and Donna told me remanufactured hubs were
$240 with a $100 core charge. I never asked her if they had new ones. But
it should be worth the additional $10. They also have hubs for $220, rotors
$125, rear drums $160.

>>
>> Are NEW knuckles available? Larry Nelson, PB-75, Springfield, MO
>
>Yep, from Cinnabar. $250 each.
>
>Patrick
>--
>Patrick Flowers
>Mailtoatri63
>
>The GMC Motorhome Page
>http://www.gmcmotorhome.com
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[patrick flowers]

>
> Patrick I have to respectfully disagree with you about "We can all
> sit here and speculate electronically til the cows come home, but you
> couldn't buy a cup of coffee with the results".
>
> We are not talking about rocket science here, nor are we talking
> about speculation. We are talking about procedures that anyone
> reading this BB can use to check their own bearings, hubs and
> knuckles. If we can't accomplish and learn these types of repair
> procedures than what is the intent of this BB?

Tom, you're confusing two different issues. There's no way we can
diagnose what happened to Lanier's coach by long distance. The only way
to confirm that is by forensic metalurgic analysis of the remains. I
doubt that you could possibly determine what the tolerances were at the
time of assembly, but you could tell what broke first and why(the direct
cause at least).

The other issue is the educational side and you're correct that we need
to discuss these issues openly and without reservation and we're doing
just that. We just can't pretend to tell Lanier what happened in his
specific case other than by speculating.

Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[zachary zehnacker]

Arch,

We don't worry too much about how much drag our race car bearings have.
Our race classes are indexed, so we have to slow them down anyway and can
actually lose if we go too fast (even if only by a .001 of a second).

I think I agree with you here, Arch, about not over-complicating the
bearing issue. We have changed the bearings in our GMC and have over
40,000 miles (I'll have to check the records, it might be closer to 50,000
now) on them with no problems. We didn't use any special tools to take
them on or off. Just some effort. We used a cutoff wheel to get the races
thin enough where they would crack when we hit them with a hammer (being
careful not to cut all the way through the race!). We pressed on the new
ones with some steel we made into a press using a hydraulic bottle jack.
There is no chance that these bearings are not on all the way. If we were
servicing these bearings all the time, then buying or making a special tool
might be worth it, but for the once every 100,000 miles or so, I don't
think it is. I don't even think a special tool would provide better
results. I also don't know how much measuring the exact clearance is going
to help. We do not have the resources to buy 10 sets of bearings just to
find the ones that are a "perfect" match to the rest of our parts. I also
don't think anyone really knows what the best possible assembled clearance
actually is anyway. By buying the right bearing set (sorry Arch but IMO
Cinnabar does win over NAPA here), it takes all the tolerances of the other
parts into account. Even these "correct" bearings, however, might have a
little too much assembled clearance if used with parts that were all on the
opposite ends of their tolerances. They should work acceptably in almost
every case though. Is it going to be perfect? Does it have to be? Is any
item that ever rolled off the GM or even the Timken assembly line really
perfect? Does this mean that it is not going to last? I'm pretty sure
that "No!" is the answer to all of these questions.

I do recommend using the GM bearing set that Cinnabar sells. It is enough
work to change the bearings that any additional cost from buying these
"correct" bearings is really insignificant. Of course I'll bet even Wes
sold some of those "bad" bearing sets that GM sold before they came out
with their updated standards. You really don't know for sure that buying
factory parts is always your best bet. It does seem to reduce the risk
though, and that is all we can really ask for.

The bearing set we replaced turned out to have been fine. Assuming the
original owner had not replaced them, they were original and had around
100,000 miles on them. Even if they had been replaced just before we
bought it, they had at least around 60,000-70,000 miles put on them by us.
They had never been greased by us, and probably not by the original owner
either. Actually, the only reasons we decided to change them were the
horror stories we had "heard" about (Thanks for clearing up some of that
Arch!). From the few stories of failures we have heard, most don't seem to
happen all that far from when the bearings were installed for the first
time. This leads me to believe that if your bearings make it to the point
where they need to be greased (20,000 miles or so IMO) they should last a
long time if you just grease them at the desired intervals.

I am also very interested in the causes of the total wheel loss failures.
I find it hard to believe that a bearing could self destruct fast enough to
give no warning whatsoever. Most of the horror stories we had heard
usually included a period of warning noise coming from the bearings shortly
before the failure. That seems to be consistent with our experience of
bearing failures on other vehicles and even the bearing failure we
experienced in our final drive.

For this reason, we usually feel all our wheels near the center at every
gas stop we make. It is our belief that if a bearing is starting to go or
a brake is stuck then that wheel will be hotter than "normal". We also use
this walk-around to take a quick visual inspection of the GMC and trailer
along the way. Since there was no warning reported in the cases of total
failure experienced by Lanier (not sure if I have his name right or not),
it seems really puzzling and a little scary. Having the exact cause
determined would be very interesting. Usually an instant failure like that
would be caused by a crack that finally made it all the way, a bolt backing
out that last thread, or some other similar event. Knowing the exact cause
might lead to some other signs to look for which would indicate that there
was a potential for this type of failure.

Zak

>Thomas
>
>WOW why are you not doing the bearing thing instead of me? Are you
>related to Wes? I have been accused of that. Now I know that my racing
>were long ago but maybe Zak or others here could help me with this.
>When we set up our cars we used to use an ounces scale to measure
>the resistance on the bearings. I will freely admit that I put in NAPA
>bearings greased them up and gave them the "little finger" test.
>Felt about right. Drove it pulled dust caps------felt about right. I know
>I am going to he** for this but its the way I learned to do it. I must
>admit I just cant believe only one machine is that different from all
>others. Hope I did not offend anyone.
>
>Take Care
>Arch 76 GB IL