rear axle shaft leak and shims ('57 Imp)

[Philippe COURANT <accf_clb@xxxx>]

I've some problem on my '57 Imperial: a leak of axle oil in the
left drum after my 1000 miles trip in May. First thought was to
blame the inner oil seal (which was replaced when i restored the
car) but after some checks it seems that the axle shaft has a lot
of transversal play so the following culprit was the outer
bearings. If the bearing goes bad, the inner (and outer) oil seal
goes bad.. I order the seals and the bearings (2788A-2735X,
specific to Imperial..) and today i remove the axle shafts.
Surprise ! There was a big axial play, at least 0.15 inch on each
axle shaft between cup and bearing.. The inner oil seal was
completly destroyed, the rubber/spring seal part was laying
around the axle completly separated of its housing !
I discovered that when i restore the axle, i forgotten to put the
"preload" shim: when you remove the rear brake plate you find
between brake support and axle shaft flange: a thick shim (around
1/10 inch) and "shimming" plates (various dimensions from 0.010
to 0.030). The "shims" have a large bore, larger than the bearing
cup, the "thick shim" has a smaller diameter equal to the bearing
cup. So when you 'shim" rear axle shaft, you add shim plates
between axle flange and "thick plate" which (with brake support)
preloads the bearing (according to FSM you must have a 0.013 to
0.018 end play at each axle).
And i forgotten to use this plate ! So the bearing was only
preload with the brake support.. Not very good as the brake
support is thin .. You'll not find in the FSM this "thick" plate
with smaller bore, itsn't also in the Parts manual (no # part)
but i had in my garage since two years 2 "shims" hanged to a
nail.. As i removed the axle 6 years ago i forgotten them !
Now i have a 0.007 end play, smaller than origin but with driving
i think i'll have a 0.013 in some miles..

Other thought: the outer bearing has no provision to grease it
from outside. It is enclosed between inner and outer oil seals so
no oil lubrication except leaks... So how to grease it (it is not
very easy to remove axle shafts..) ? Itsn't a sealed bearing or a
"life" warranty bearing.. No indications in the FSM lubrication
chapter. I've put a lot of grease ..

If someone needs 2788A-2735X bearings i've a pair of new Timken
...(bought from Dallas seller, thanks John !). And no thank to
Andy Ber... who sent me wrong (outer) oil seals, no bearings and
wrong filters for a friend..

--
Philippe COURANT (Pau, France)
Imperial 57 Crown convertible
Buick 58 Roadmaster sedan

- American Car Club de France (ACCF) : http://www.accf.com

- Chrysler Imperial France : http://www.ifrance.com/c-i-f

- Cadillac " Standard of Excellence " :
http://www.ifrance.com/accf-cad

- SportsCars : http://www.ifrance.com/accf-sprtcar