Yes you need the shims. A simple way to get the bearing shimmed properly is
to...
Realize that more shims means more play... Less shimms/less play
I usually put any two in and see how it fits. If it spins freely and wobbles
at all remove the shims and with your assortment of shims, make a
combination that is just a bit smaller... retry. If the rotor binds on the
bearign you've gone too far, add a shim.
I keep going untill I get just a wee bit of drag on the rotor then back off
the smallest shim I have. As long as you cannot feel any rocking and the
rotor spins fairly freely your fine.
You must use the shims to adjust the bearing. Torquing the nut down to
compensate for excessive play will only squish the inside race of the
bearing and posibbly crack it or otherwise put stress on it. On the other
hand, if you are trying to compensate for the bearing binding by backing off
the nut a bit the inner bearing will not be seated properly against the
conicle spacer. Buy a bunch of the shims and play with it. They're cheap.
Chris Reichle
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From: mgs-owner
To: John Bartholomew
Cc: airhedrz; mgs
Subject: Re: Replacing rotors (query)
Date: Wednesday,November 13,1996 10:15AM
John Bartholomew wrote:
> <snip>
> When you have the hub and disc off, the outer bearing falls out, look for
> the shim washers that are behind the outer bearing between it and the
large
> cylindrical spacer that fits between the inner and outer bearings on the
> axil shaft. There are four sizes of shim washer that you may encounter, 3,
> 5, 10 and 30 thousandths thick. These can be in any combination to provide
> an end float of about 4 thousandths, when the nut is tightened to the
> correct torque. A dial gauge is useful but not essential.
> It is a good idea before pulling it all apart, to get a feel of what the
end
> float is like. Grab the disc with your hands on opposite sides and try to
> pull and push on it, sliding it on its axil. There should be just
> perceptible movement, NO movement is not acceptable! <snip>
Whoa there! I would like to hear some dialog on those lousy shims. Three
cars
and several years ago I read carefully the instructions on those shims that
should
be fitted between the outer race and the conical spacer. And I read all the
details on measuring the gap --- and I decided it was all a bunch of hooey.
I think that trying to measure .004 play is impossible because:
1) Once the new assembly is packed with grease you won't feel any and
2) what you do feel is (acceptable) play in the kingpin.
But, anyway, swapped new bearings a long time ago and measured just as
careful as
I could and snugged the axle nut back in with all that new grease and could,
in
fact, feel some (minimal) play. But on the first test drive, the new grease
made
itself comfortable inside the hub and added some more play and the car
steered
horribly.
I think the only way you could get a realistic measurement is if you
assembled the
whole mess dry -- without any grease -- and futzed with the shims until you
got a
little play. Then took it all apart again to pack'em with grease. And I
still
don't know how you could attribute 4 thousands to the axle rather than the
kingpin.
So now I repack the bearings every other year, have long since discarded the
shims, and just tighten the axle nut like and old Chevy: Torque it down good
and
hard to "set" the bearings and then back it off to the second hole in the
axle
crown nut. I've never had a bit of problems in any of my cars.
So what's the scoop? Why would just the British have the shims and are they
really
important with modern bearings? If someone want's to tell me the dire
consequences
of losing the shims, I guess I'd like to know when they might be showing up.
They
haven't in 30,000+ miles.
Bob Allen, '69MGC/GT, Kansas City
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