John:
Thank you for the additional discussion of the rear
axle bearings. Now that I have looked at my service
manual, there doesn't seem to be a service interval for
the rear axle bearings, only an inspection of the front
axle bearings every 20,000 miles. That should teach me
to talk off the top of my head. I guess the only time
you really need to pay attention to these bearings is if
they are noisy or diff' lube is leaking past the outer
seal.
I had an old Chrysler mechanic and former 300 club
member who replaced and repacked the rear axle bearings
in my two convertibles when both had noisy bearings in
the rear. Unfortunately, he has since passed away.
Anyway, he used to speak repeatedly about "the button".
I believe this is the thrust spacer of which you
mentioned. According to my mechanic's stories and as
verified in the service manual, "the button" or thrust
spacer, is only present on one side (the bolted side) of
the Sure-Grip differential assembly. There is no button
on a standard differential as I can find. I have had
rear axle bearings replaced on only two of my cars and
my mechanic at the time did those. I personally
repacked the rear axle bearings and replaced the grease
seals in my 1962 300 coupe after I found diff' lube
oozing past the outer seals. Standard differential here
meant no button and I put it back together with no end
play issues. The rear axle bearings in my other cars
have never been apart since I have had them. My old
mechanic had his own custom made "fishing tool", a long
slender rod, bend in a special way, with a magnet on the
end. He used that tool to go "fishing for the button"
whenever he pulled the axles on a Sure-Grip.
Words of wisdom for the ages.
Chris the KMANIAC
-----Original
Message-----
From: John Grady <jkg@xxxxxxxxxxxxxxxxx>
To: kmaniak <kmaniak@xxxxxxx>; jymopar
<jymopar@xxxxxxxxxxxxxxx>
Cc: chrysler300 <chrysler300@xxxxxxxxxxxxxxx>
Sent: Wed, Jul 30, 2014 1:21 pm
Subject: RE: [Chrysler300] gear lube
Thanks Chris..I was not trying to say
anything about lubing wheel bearings , as no
brass out there , but very good point. I knew
of the dual seals, but to be frank never
thought about why, other than “wow. Cool!
additional protection against brake
contamination”. Kind of an odd design,
compared to rest of industry . I think
eventually all with open axle bearings ended
up sharing wheel lube with diff lube, to my
knowledge, or else sealed ball bearings. I
like very much the shimmed Timken design from
an engineering perspective, much better than
GM pressed ball bearings on Chevs ; there is a
reason RR freight cars have Timken…not ball
bearings , but perhaps the (?.013) side to
side motion possible with Chrysler / Timken
design makes seals unhappy.
Do you know you can insert the nail
shaped thrust bearings in thrust block without
opening axle? Drill a hole in new one, maybe
1/8, put on end of two welding rods welded
together end to end that fit in that drilled
hole , heavy grease , get very bright
flashlight, you can do it from wheel opening.
Often when pulling axles, these “brass nails”
stick to axle ends as you draw out axle, pull
out of their hole, then drop to bottom of
pumpkin, then you cannot shim it…big gap.
People take out all the shims , still loose
,and unbelievably button it up . If you drive
it like that, back brakes burn up due to
touching drum, brake drum and axle now ride
off center . How I learned all this pain , was
back in 69. F by side of road in Chicago, in
snow, on way to Boston. Just bought it from a
guy who “did brakes “and “had to change wheel
bearing seals”. Right. Smoke pouring off
brakes 50 miles away. If you pull an axle ,
look in there…… a big “OH NO” often awaits if
you see a hole and no nail..
I also remember “bought new” 60 Dodge
getting grease on brakes at 80k, locking up,
very common failure in these axles when
relatively new, but bearing OK—brakes sure
were not. ; whether it was grease or axle
fluid I do not know; I believe this was quite
an old design, maybe back to first Mopar
axles. I wondered that first time “why didn’t
they just put a drain slot or hole at backing
plate to let any seepage out, instead of
forced onto brakes?
One wonders if they really need
repacking every 25, (why would that be? No
technical reason..really) or if that was a
service revenue move. They do not now(fronts w
same design, dual Timkens are common, as is
“greased bearing sealed for life” ) ;
Given you might pull out the thrust
bearings, leading to pulling pumpkin for a
reward to your good intentions, I’d tend to
wait for sign of trouble, brake or bearing,
leave well enough alone---you can do more harm
than good rather easily, if you pull axle .
my .02. your mileage may vary, no issues with
that here . Question authority, and all that.
John
John, thanks for the heads up on
this.
Having said that, the wording of your
notice could lead the reader to believe that
the rear axle bearings, located at each
wheel end of the differential housing, are
lubricated with the same gear lube as the
differential assembly. For 1964 and older
Chryslers, including letter cars, this is
not true. On these cars, the rear axle
bearings are packed in axle grease, the same
as the front wheel bearings. The greased
axle bearings are contained and sealed with
two grease seals, the inner grease seal that
prevents the impingement of gear lube from
the inside, and the outer grease seal
mounted in the backing plate that prevents
grease from contaminating the brake
linings. Chrysler recommends repacking the
rear axle bearings every 25,000 miles or at
the same interval as the front axle
bearings. This requires pulling each axle
shaft and replacing both seals on each
side. Any leakage of gear lube into the
brake drum indicates that BOTH seals have
failed.
Many letter cars owners are aware of
this design and required maintenance. But
you would be surprised how many Chrysler
owners I have met over the years who were
completely unaware. So I thought I would
mention this for clarity.
Found
out some interesting ,--
could be important ---stuff.
In
Auto Restorer; GL-5 gear
lube has sulphur and other
additives that attack brass,
so not for use on manual
transmissions or rear axles
with brass / bronze parts ;
GL-4 OK ; I know 300F has
brass thrust bearings in
Axle center (Timken style
rear wheel bearings) , many
cars of our vintage had
brass transmission syncros ,
brass bushings in diff, etc
. I have been using
synthetic 75W Mobil 1, not
sure now if GL-5 or 4; GL-5
made for all 100% steel
bearings, like ball bearings
etc typical of new cars , EP
additives help those, are
in GL-5
No virus
found in this message.
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Posted by: Bob Merritt <bob@xxxxxxxxxxxxx>
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