Bearings again and a proposal

H

hdavis

New member
Mar 13, 1998
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>Henry as I am sure you are aware, over 90% of bearing failures are caused by
>seal failure and improper lubricants.
>

The statistics that I've seen say about 50% to seals and about 50% to
lubricant. Some tend to remove improperly installed bearings from the
dataset, but some studies have indicated up to 30% of failures are due to
incorrectly installed bearings. This is across all types of equipment and
not just automotive. Incorrectly installed bearing failures include over
lubrication (increases rolling resistance) and under lubrication.

None of these statistics have been validated against the GMC front bearing
failure data. Keep in mind that most of the bearing data comes from
industrial installations where they use ferrography or spectroscopy to
monitor changes in the lubrication at regular intervals.

Still, I think that the statistics should be used as a general guide to the
GMC front end.

Timken has a good site for their bearings at at
http://www.timken.com/bearings/fundamen/ They have recently added a page on
visual evaluation of bearing failure. Here's what they say about premature
bearing failures in their experience: "Damage to bearings while handling
before and during installation and damage caused by improper installation,
setting and operating conditions are, by far, the causes of the largest
percentage of premature trouble."

If someone has the time to detmine all of the GMC specific factors, there
is a method of calculating bearing life at
http://www.timken.com/bearings/fundamen/calculate.asp

Here's my proposal to GMC netters:

When you have your front bearings replaced send them to me with a sample of
the lubricant. Let me know miles since they were last changed and front
axle weight if you have it. I'll work with the folks at Timken to build
objective data about "bearing failure" in the GMCs based on physical
evaluation of bearings removed from service.

Henry
Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com/ http://www.henry-davis.com
 
Henry we appear to be on the same wavelength on the front bearing failure
issue. From my experience with the toronado front end, the number of
individuals and garages that had the proper seal drivers, bearing removers
and reinstallation equipment was 0. Few understood how to properly install
a seal, what it did and the proper depth to install it.the large socket is
the primary tool of choice when installing new bearings and seals, sometimes
with a press but more times with a hammer. Ring a bell with anyone? I have
to admit that I did it that way at one time because I didn't know any better.

I witnessed mechanics using a bearing packer tool that was air powered,
brought from under a work table, with greasy hands that attracts sand like a
magnet. In addition the tool was covered with dust and probably
contaminated with sand from the floor and than pack grease in a new bearing
with it. I would never, never, never,recommend the use of such a tool to
pack bearings. It only takes a few grains of sand in the grease to destroy a
bearing fast.

This was my motivation for having the proper bearing puller and reinstaller
manufactured at a reasonable price, so the bearings can be installed and
removed correctly by anyone. Everyone that is going to service their own
front ends needs a seal driver and heads for it very economically bought
from J.C. Whitney or Summit.

Bottom line is when you install new bearings in your front end, clean
everything carefully before you start and don't do anything that could
possibly introduce dirt into the bearing, knuckle or hub. Use clean fresh
grease and always handle it with clean hands, and keep the grease stored in
a closed container high off the floor. Keep the floor covered with a heavy
piece of cardboard or something similar so dirt can't be picked up by
accident. I even wet the floor down.

I think that the main cause of bearing failure in our coached can be traced
to wrong bearings, incorrectly installed with the incorrect grease, and
contaminated. Take your pick. I think if we all install new bearings using
this procedure we can forget about bearing failures.



>>Henry as I am sure you are aware, over 90% of bearing failures are caused by
>>seal failure and improper lubricants.
>>
>
>The statistics that I've seen say about 50% to seals and about 50% to
>lubricant. Some tend to remove improperly installed bearings from the
>dataset, but some studies have indicated up to 30% of failures are due to
>incorrectly installed bearings. This is across all types of equipment and
>not just automotive. Incorrectly installed bearing failures include over
>lubrication (increases rolling resistance) and under lubrication.
>
>None of these statistics have been validated against the GMC front bearing
>failure data. Keep in mind that most of the bearing data comes from
>industrial installations where they use ferrography or spectroscopy to
>monitor changes in the lubrication at regular intervals.
>
>Still, I think that the statistics should be used as a general guide to the
>GMC front end.
>
>Timken has a good site for their bearings at at
>http://www.timken.com/bearings/fundamen/ They have recently added a page on
>visual evaluation of bearing failure. Here's what they say about premature
>bearing failures in their experience: "Damage to bearings while handling
>before and during installation and damage caused by improper installation,
>setting and operating conditions are, by far, the causes of the largest
>percentage of premature trouble."
>
>If someone has the time to detmine all of the GMC specific factors, there
>is a method of calculating bearing life at
>http://www.timken.com/bearings/fundamen/calculate.asp
>
>Here's my proposal to GMC netters:
>
>When you have your front bearings replaced send them to me with a sample of
>the lubricant. Let me know miles since they were last changed and front
>axle weight if you have it. I'll work with the folks at Timken to build
>objective data about "bearing failure" in the GMCs based on physical
>evaluation of bearings removed from service.
>
>Henry
>Henry Davis Consulting, Inc / new product consulting
>PO Box 1270 / product readiness reviews
>Soquel, Ca 95073 / IP reviews
>ph: (408) 462-5199 / full service marketing
>fax: (408) 462-5198
>http://www.henry-davis.com/ http://www.henry-davis.com
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
 
>Henry
>
>Please do me a favor. Ask the people at Timken a question for me. How
>much does it shorten the life of a bearing by taking it off and putting it
>back on. I have not mentioned this before but back in my racing days
>we came to the conclusion that the only bearing we had to fail were
>ones we had taken off and serviced. This my well have been a myth.
>To this day I never reuse a bearing. If I am going in---------the bearing
>is history. I would like to hear what the big boys have to say. Thanks.
>

Timken applications guys said that removing and reinstalling os OK.
HOWEVER, they observed that most people do not clean the beartings
adequately or correctly. Also, fingerprints can etch the steel and cause
spauling sites to be formed - leading to early failure. Do keep in mind
that a lot of Timken's hard data comes from stationary equipment that has
regular lubricant sampling schedules.

Timken recommends a pretty rigorous cleaning procedure. Also, they
recommend leaving bearings in their original packaging until they are going
to be put into service.

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com/ http://www.henry-davis.com
 
Thomas and Henry,

Your posts on the important need to keep the bearings free of dirt and
grit when servicing them reminded me of the latex rubber gloves that the
mechanic put one when unwrapping and packing the grease in the new
bearings he installed on my Transmode. As I watched the proceedings I
commented to him that gloves made sense because of the mess the new
grease was making on his hands. He replied, "Naw, its to keep the
bearings clean". Looks like I got a good job in that regard. When I
get my new Warner bearing tools I'll buy me some disposable gloves as
well. Thanks for your in sight on this important subject.

Phil Stewart
'76 Transmode, TN

P

P

>
> Henry we appear to be on the same wavelength on the front bearing failure
> issue. From my experience with the toronado front end, the number of
> individuals and garages that had the proper seal drivers, bearing removers
> and reinstallation equipment was 0. Few understood how to properly install
> a seal, what it did and the proper depth to install it.the large socket is
> the primary tool of choice when installing new bearings and seals, sometimes
> with a press but more times with a hammer. Ring a bell with anyone? I have
> to admit that I did it that way at one time because I didn't know any better.
>
> I witnessed mechanics using a bearing packer tool that was air powered,
> brought from under a work table, with greasy hands that attracts sand like a
> magnet. In addition the tool was covered with dust and probably
> contaminated with sand from the floor and than pack grease in a new bearing
> with it. I would never, never, never,recommend the use of such a tool to
> pack bearings. It only takes a few grains of sand in the grease to destroy a
> bearing fast.
>
> This was my motivation for having the proper bearing puller and reinstaller
> manufactured at a reasonable price, so the bearings can be installed and
> removed correctly by anyone. Everyone that is going to service their own
> front ends needs a seal driver and heads for it very economically bought
> from J.C. Whitney or Summit.
>
> Bottom line is when you install new bearings in your front end, clean
> everything carefully before you start and don't do anything that could
> possibly introduce dirt into the bearing, knuckle or hub. Use clean fresh
> grease and always handle it with clean hands, and keep the grease stored in
> a closed container high off the floor. Keep the floor covered with a heavy
> piece of cardboard or something similar so dirt can't be picked up by
> accident. I even wet the floor down.
>
> I think that the main cause of bearing failure in our coached can be traced
> to wrong bearings, incorrectly installed with the incorrect grease, and
> contaminated. Take your pick. I think if we all install new bearings using
> this procedure we can forget about bearing failures.
>
>
>

> >>Henry as I am sure you are aware, over 90% of bearing failures are caused by
> >>seal failure and improper lubricants.
> >>
> >
> >The statistics that I've seen say about 50% to seals and about 50% to
> >lubricant. Some tend to remove improperly installed bearings from the
> >dataset, but some studies have indicated up to 30% of failures are due to
> >incorrectly installed bearings. This is across all types of equipment and
> >not just automotive. Incorrectly installed bearing failures include over
> >lubrication (increases rolling resistance) and under lubrication.
> >
> >None of these statistics have been validated against the GMC front bearing
> >failure data. Keep in mind that most of the bearing data comes from
> >industrial installations where they use ferrography or spectroscopy to
> >monitor changes in the lubrication at regular intervals.
> >
> >Still, I think that the statistics should be used as a general guide to the
> >GMC front end.
> >
> >Timken has a good site for their bearings at at
> >http://www.timken.com/bearings/fundamen/ They have recently added a page on
> >visual evaluation of bearing failure. Here's what they say about premature
> >bearing failures in their experience: "Damage to bearings while handling
> >before and during installation and damage caused by improper installation,
> >setting and operating conditions are, by far, the causes of the largest
> >percentage of premature trouble."
> >
> >If someone has the time to detmine all of the GMC specific factors, there
> >is a method of calculating bearing life at
> >http://www.timken.com/bearings/fundamen/calculate.asp
> >
> >Here's my proposal to GMC netters:
> >
> >When you have your front bearings replaced send them to me with a sample of
> >the lubricant. Let me know miles since they were last changed and front
> >axle weight if you have it. I'll work with the folks at Timken to build
> >objective data about "bearing failure" in the GMCs based on physical
> >evaluation of bearings removed from service.
> >
> >Henry
> >Henry Davis Consulting, Inc / new product consulting
> >PO Box 1270 / product readiness reviews
> >Soquel, Ca 95073 / IP reviews
> >ph: (408) 462-5199 / full service marketing
> >fax: (408) 462-5198
> >http://www.henry-davis.com/ http://www.henry-davis.com
> >
> >
> >
> Tom & Marg Warner
> Vernon Center NY
> 1976 palmbeach
 
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