Arch you could not have been a hippy! "Flower Power", "make love not war"
those were the cries of the 60's. hippies didn't fight they made love!
Guys this is getting worse fast. The misinformation is mounting up and will
get some poor sole in trouble if they take them as gospel. In the case of
wheel bearings, if you want to get stranded somewhere with seized
bearings,spend a lot of money correcting the effects of an improperly
selected and installed bearing, you stand a good chance if you follow some
of this advice. Bearings are a pretty exact science and the correct
information is available if you want it. =20
Why are we arguing over bearing information that is substantiated by good
old common sense fact? If you use the correct bearing and install it
correctly you will not have a problem, period. Are you worried about saving
a couple of dollars here? =20
Arch when I used the word academia it was used in the context that all of us
are learned(I have a few degrees also) to some degree and are semi-literate
in the proper maintenance procedures for the GMC motorhome. Usually when we
discuss a subject, many, many put in their two cents worth, and eventually
we arrive by a system of bantering back and forth a meeting of the minds as
to the correct, safe, cost effective method or part to use in keeping our
coaches on the road and out of the shop.
In the case of wheel bearings, opinions are worthless and can be down right
dangerous, unless they are backed up by fact. We are not being fair to our
other netters when we put forth information that is either unsubstantiated
or just plain untrue. Timken has done a tremendous amount of research and
produces a bearing that will run for a very long time maintenance free, IF
YOU INSTALL THE CORRECT BEARING IN THE CORRECT MANNER!
One more time: the Timken bearing that you buy in your parts store is not
the same bearing that Cinnabar sells. Cinnabars part number 12351677 is a
timken bearing with .095" of unassembeled axial clearance. They have been
specifically selected by Timken and assembled for use in the GMC motorhome.
Can you buy a bearing like this at the parts store. Maybe, if by chance you
got one with .095" of clearance. I went through this and tried at my local
parts store and after 10 sets of bearings gave up.
Want to convince youself? Install two different bearing sets on your hub
(off the vehicle of course), install a half shaft, washer and nut and torque
it to 140 ft lbs and than measure the axial clearance of the two sets. You
will probably out of 10 sets not get any two with the same readings.
An opinion that can get you in trouble fast:
1. "If I had to do a GMC with off-the-shelf bearings, I'd be tempted to use
the old shims if still in good shape.
Please. You can't use a shim from one bearing set with another set of
bearings unless you know how to measure the axial clearances AND extrapolate
to the installed clearance when taking into account YOUR COACHES hub and
knuckle dimensions. To use a shim from one bearing with another set is just
plain dangerous.
I have included some information from the Timken Company site:
WARNING!
Never spin a bearing with compressed air. The force of the compressed air
may cause the rollers to be expelled with great velocity, creating a risk of
serious bodily harm.
Proper bearing maintenance and handling practices are critical. Failure to
follow installation instructions and failure to maintain proper lubrication
can result in equipment failure, creating a risk of serious bodily harm.
If a hammer and mild steel bar are used for bearing removal, fragments from
the hammer, bar or the bearing can be released with sufficient velocity to
create a risk of serious bodily injury including damage to your eyes.
=A0=20
Bearing Maintenance Frequently Asked Questions=20
Proper maintenance procedures are essential for achieving maximum bearing
life and performance. Regardless of the bearing type, application or
operating conditions, regular maintenance schedules should be established
and rigorously
kept.=20
Bearing and equipment manufacturers work together to specify the techniques
and frequency of removing, inspecting, cleaning, lubricating, reinstalling
and adjusting bearings, along with the type and amount of lubricant needed.
These recommendations are important when scheduling and setting guidelines
for periodical bearing
check-ups.=20
Following are answers to some commonly asked questions about bearing
maintenance. We hope these tips will help you gain optimum performance and
long life from your
bearings.=20
Q: What do all the prefixes and suffixes on a Timken=AE bearing mean?=20
A: Even the most common Timken bearing has dozens of variations. The letters
in its prefix normally designate the duty class of the series, and the
letters in its suffix designate a type of external modification from the
basic part number. For example, an "M" prefix on a cup or cone part number
designates a medium series. Another example is the commonly used "CD"
suffix, which designates a double cup with groove and oil holes, one of
which is counter-bored for a locking pin. An explanation of all Timken
bearing symbols is included in The Timken Company Bearing Dimension Guide,
which is available from your local Timken
distributor.=20
Q: What can I do with cones that won't come off, even with a bearing puller?=
=20
A: Sometimes it is practical to carefully pour heated oil on the cone at the
same time you=92re applying pressure through a puller. The heat will expand
the bearing cone and make it easier to get
off.=20
Q: I need to replace a double-row spacer bearing. Can I just replace the two
single cones to avoid the expense of replacing the entire bearing?=20
A: Absolutely not. The parts must be assembled as a unit and not mixed or
interchanged with parts from other assemblies. Spacer bearings are supplied
as complete assemblies. Cone spacers control bearing internal
clearance.=20
Q: Can large-bore bearings for industrial applications be repaired?=20
A: The Timken Company has a Bearing Repair and Service Center for large-bore
tapered roller bearings. Repair capability ranges as high as 84-inches
outside diameter (OD) and 19,000 pounds. While reconditioning is not always
the best alternative, bearings can often be returned to original
specifications, including the same warranty, for less time and money than
purchasing a new
bearing.=20
Q: When it comes to greasing bearings, is more better?=20
A: The more-is-better philosophy is a common misconception about greasing
bearings. It=92s like taking 10 aspirins for a headache. Follow the specific
guidelines provided in literature published by The Timken Company, and
always follow manufacturers=92 recommendations. These will help you=
lubricate
just the right way... and with just the right amount. Too much grease in the
bearings and housing will cause excess churning of the grease and will
result in extremely high
temperatures.=20
Q: Should I use a micrometer to measure the shaft and housing every time I
replace a bearing?=20
A: Absolutely. A bearing is no better than the housing it is mounted in or
the shaft it is mounted on. Verifying that cone seats and housing bores are
the right size is a good long-term investment. Be sure all measurements meet
the manufacturer=92s
specifications.=20
Q: When mounting a Timken bearing, should heat be applied?=20
A: You should never heat a standard Timken bearing more than 300 degrees
Fahrenheit, and precision bearings should never be heated more than 150
degrees Fahrenheit. Also, there is a tendency for the hot cone to pull away
from the cold shoulder during installation. After the cone has cooled, be
sure to check with a 0.002" feeler gauge to see that it is snug against the
shoulder where it
belongs.=20
=20
---------
>
>> I imagine the bearings are the same at NAPA as they are at Cinnibar. The
>> difference, I'd expect, would be in the garrantee that the bearing 'set'
>> would be the one within the tolerance specified for our GMC's. =20
>> =20
>> It's really all in that little round steel spacer.
>
>Rushing in where angels fear to tread.....
> I think Billy's got something here. I do not believe that Cinnabar's=20
>Timkens can carry any more weight than NAPA's, and I seriously doubt they=
are=20
>the "pick of the crop" at Timken.
> OTOH, what I can believe is that the selection and packaging of just the=
=20
>right spacer is what sets Cinnabar's bearing SETS apart. Since we (of=20
>necessity) run with firmly tightened front axle nuts, that spacer must be=
=20
>thick enough to ensure the bearings are not too tight, (nor too loose).
> Just to complicate things, I recall that some Japanese front-wheel-drive=
=20
>cars used the same system of roller bearings and shims. Mercifully, I=
rarely=20
>had to replace any like that, as the shop manual gave a long arduous=20
>procedure of assembling with a dummy spacer, measuring the preload torque=
of=20
>the bearing, then selecting the right spacer. Never heard of anyone=
actually=20
>doing all that. IIRC, the shim selection was as much to compensate for=20
>variations in the steering knuckle as in the bearings. If I had to do a=
GMC=20
>with off-the-shelf bearings, I'd be tempted to use the old shims if still=
in=20
>good shape.
> In closing may I say I'll buy my Cloyes timing chain from J.C.Whitney or=
=20
>whomever, but for now at least I'll go to Cinnabar for front wheel bearing=
=20
>sets.
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
"The beautiful Mohawk Vally"
