Just to get some controversy going again, here is my expereience with
these bearings:
First, don't mess with these bearings until you have purchased a dial
indicator if you intend to use the shim/spacer method.
The only time I have ever burned a wheel bearing was when I attempted to
set this up without one back in about 1970. After consulting with the
dealership mechanic about this, he said it wasn't really necessary to
use the shims if you replaced the factory bearings with new bearings (he
wouldn't do this at the dealership however). The standard procedure of
tightening the hub until rotating resistance is felt (rotate with the
wheel on for leverage) and backing off just to the cotter pin line up
works fine. I've been doing this for over 150,000 miles in the last 30
years.
The reasons for the shims are certainly valid if you want to go to the
trouble and expense of buying a good dial indicator. As I recall they
were used for the following reasons:
At that time disc brakes on high volume production cars were a rarity,
with only the Europeans using them. The shim method provided a fail
safe procedure for mechanics who were unfamiliar with the system.
The design was also of the fixed caliper type as opposed to the modern
floating caliper, which meant that any side to side movement of the disc
from loose or worn bearings would result in excessive brake pedal travel
(pads are pushed away from each other and a large gap is created that
may result in complete loss of stopping power without multiple pedal
presses).
Hence, if the hub with its disc is "locked" into a precise position with
a spacer and shims, every car leaving the factory will have minimal
pedal travel, and any mechanic who will RTFM can work on the brakes
safely.
Also, British metallurgy of the '50s and '60s was not all that great,
and that was reflected in the quality of their bearings as well. This
is apparently why the mechanic said to replace the factory bearings.
The shim method is certainly the best because of it's precision, but I
don't think it is absolutely necessary. So, if you find the spacers are
lost and you don't want to buy a dial indicator, you can still be safe
if you do the job properly.
--
Stuart MacMillan
Seattle
'84 Vanagon Westfalia w/2.1
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)
Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)
Parts cars:
'68 & '73 MGB, '67 MGB GT
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