Your specialist is absolutely right. There must be no "end play" in the
pinion. If there is the front pinion bearing, which takes the thrust, is
worn or too loose. End play will very quickly ruin the pinion gear or crown
wheel. In addition, there must be no SIDE play at the pinion, this is
controlled by the tightness of the straight roller bearing at the rear.
Measureable side play means the roller bearing is worn.
I have set up my J2 differential ( same design as M type ), using modern
tapered roller bearings and when these are slightly pre-loaded the pinion is
fixed in position. The tapered roller bearings also have a much greater
strength and locate the pinion better than the original roller/ball
bearings. Tapered rollers also alllow use of some Loctite Bearing Mount ( or
similar ) to be smeared on the outer races before assembly to tighten the
fit of the outer races in the bevel pinion housing. The inner races are
clamped by the pinion nut when it is torqued up.
Original set-up was single row ball/thrust bearing at the front, spacer,
roller bearing at rear next to the pinion gear.
Find out why there is end play and repair the problem. Tapered rollers will
certainly be a better long term solution. However use of tapered rollers
means a bit more set-up time as the pinion bearings will need to be
pre-loaded to about 5-6 lb-inches. Also the pinion location must be
accurately set with the tapered rollers in position. I would check the
location of the pinion BEFORE stripping the diff apart, fit the tapred
rollers, then set the pinion back to the same location using appropriate
shims.
A good description of setting up a tapered roller bearing diff can be
found in Blowers MG Workshop Manual under Rear Axle, 1 1/4 litre Series Y,
pages 196/198.
Regards, Bob Grunau
Hello,
I have just put my M-Type diff in to a specialist to be set up. The chap
that's doing the work has noticed that there is some 'end play' in the
pinion shaft and he is not sure if it was assembled in the correct order. He
says that there are two bearings, a thrust bearing and a carrier bearing for
the pinion. He is wondering if they may have been transposed at some time.
Does anyone have any knowledge of the way all of the pinion bits and pieces
go together ? Or is the 'end play' normal for these cars. My specialist
thinks it will cause problems on deceleration.
Lyndon Pope.
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