[200q20v] Wheel Bearing Postmortem, ws Note to Benz Strut Brace users.
b.m.benz at prodigy.net
Thu Nov 15 23:36:59 EST 2001
They can't both be broke, and they wern't!
My conjecture is that the strut brace rigidly couples the unsprung masses of
each side together mechanically and also these unisolated masses together in
such a strong manner acoustically that it was impossible to determine, while
driving, which side the rumble was originating from.
The bearing postmortems revieled that both bearings were on the verge of
suffering from a lack of lubrication at 140K miles, the grease being hard
and not in contact with the balls. But only one bearing had any sign of
damage, gauling on one of the two outer ball races. A little imperfection
can surely make a lot of rumble noise.
But the second bearing wasn't broke! So, after the thorough cleaning
required for this inspection, it was easier to relube and reassemble the
good one rather than indure the fight to remove the inner race from its hub
for a new bearing. I did so, and now have one new, and one rebuilt bearing
installed. Put your money on the winner! Mine is on the rebuilt one,
as I know its total condition. Another 250K will maybe tell.
The anti-sway bar bushings to the lower control arm were in good shape and
not needing replacement at 140K, but I decided to increase the compression
on them anyway. Did so by grinding 1mm from the center spacer of each
bushing half, thus increasing the total bushing squeeze by 2mm. (BTDT
before, different car)
The ball joints and tie rod ends were tight and sound, so relubed them by
injecting oil around the boots, hypo needle between shaft and boot. (BTDT
The strut top thrust bearings were dry. Disassembled, cleaned and
regreased. Careful! Lots of uncaged little balls. (BTDT)
Tightened down 1/2 turn on the Koni rebound setting, after 25K miles.
One big, dirty job! Pro wrenches earn their keep.
I'm currently doing a front wheel bearing replacement job on the 200Q-20V.
I can't tell which one is bad, even with a stethascope, so I may be forced
to replace both sides. Heaven Forbid! They can't both be broke can they?
But they sure have become real growlers over the past 6 months.
Anyway, when removing the strut assembly you can save a little grief by
removing the brace from the strut rod end and replacing it with just the nut
while the car is still on the ground, as a first step. This will allow the
strut assembly to be removed in one piece, rather than having a loose spring
cause parts to fly all over. Add this note in your Bentley, pg. 40.11.
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