In a message dated 96-04-09 03:14:19 EDT, NamasteRH(at)aol.com writes:
>I need to rebuild my servo. Fine. The question I need your collective
>advice on is two-fold.
>
>Firstly, SHOULD I rebuild my servo? In December there was a spurt of
>discussion about the best replacement servos, but nada about rebuilding.
So,
>has anyone done it recently (last few years), whose kit did you use, and
were
>you happy with the results? Sunbeam Specialties seems to have the best
price
>for the kits (5 or 7 in.) but their price is SO MUCH LOWER than the
>competition that I am worried about quality. Comments? If the results
>(regardless of the kit used) will be short-lived, I don't want to waste my
>money on a kit. HELP!
>
>
(The following are notes from a Pacific Tiger Club tech session given by
Larry Atkisson a few weeks ago in Seattle. My apologies to Larry in advance
for any omitted information)
Most servos are rebuildable, though the 5" or 7" can (vacuum cylinder) and/or
air piston leather seal is sometimes too corroded to reuse if its been
sitting too long full of moisture-absorbing brake fluid.
For best results, you'll want to rent a couple of hones to properly clean up
the servo body bore and the inside of the can. (Even if there's no rust, the
can builds up a glaze over time that needs to be removed.) You'll also need
a quality pair of inside-style circlips pliers. Follow the directions
carefully; however; you don't have to make up the illustrated special wire
tool to hold the piston-valve assembly in place while extracting or
installing the retaining circlip. A long, slim screwdriver will do.
Note that the rubber seals are directional. The diagram in the instructions
can be hard to read, so remember the direction of the old seals before
disassembling. Coat the seals and bore with fresh brake fluid when
reassembling.
The most frequent failure after a rebuild is that the vacuum piston 'sticks',
causing the brakes to drag or even lock up on their own. On the Girling
rebuild kits, you can avoid this by cutting down the replacement rubber seal
(that fits under the edge of the leather seal on the air piston) to half its
diameter, or by reusing the original seal if its in decent shape. I'm told
that the latest kits from Sunbeam Specialties address this problem by
supplying a slimmer diameter seal.
The lack of moisture absorbtion by silicon fluid makes it the recommended
choice.
Dick Sanders
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