RE: Rebuilding calipers

["Greg McNair" <gmcnair@domain.elided>]

From: jason.glover@domain.elided
Subject: To Rebuild Calipers or Not...?

........ Is rebuilding the calipers myself worth the
exposure to solvents and possibility of future brake
failure? How tough is it?..........

Jason, to answer your question, this was my own experience:

1984 Spider, ATE rear calipers.  I separated my caliper halves, and discovered
cracked rubber seals and frozen pistons (my car sat for quite awhile also).  A
local, excellent Alfa mechanic, (thanks Stephen) suggested that I push out the
pistons with grease.  I did that once, and it worked like a charm, but I
learned from that experience and used air on the second caliper set.

When you split the caliper, you will discover an inlet and an outlet for the
brake fluid on one half, and an inlet, outlet, and the main fluid "in" port on
the other half.  Start with either half.  Using a c-clamp and one of your
brake pads, put the smoothest side of the pad against one of the fluid holes,
blocking air escape.  Wrap a rag tightly around the caliper, creating a catch
for the piston.  Using your air compressor nozzle (preferably with a rubber
tip to create a good seal), force air into the open port.  The air pressure
will push the piston out into the rag.  Be sure to wear safety glasses, as
undrained brake fluid will find it's way into your face.  The half with 3
holes will be a bit trickier, as you will have to block both fluid ports with
pads, and you'll use the main fluid entry port as your air inlet.  The caliper
halves share a very small rubber washer.  Do not lose this.  If you do, don't
despair, as Paul Spruell's shop in GA carries these.  Go ahead and order a
pair of them just in case yours are shot.  You'll need one washer per caliper.
Many folks will tell you that you should never split a caliper.  Hogwash.  So
long as the smooth faced surfaces are absolutely clean and burr-free, and you
reassemble them properly, you should never have a problem.  Just be sure to
use plenty of brake cleaner, and clean each caliper half thoroughly.  The
caliper rebuild kit, about $15, combined with a couple hours' worth of work,
is much easier on the wallet than a "new" rebuilt caliper at $100.  The reason
I suggest using air in lieu of grease is that grease makes a mess.  Grease
doesn't compress very well, so it does a fine job of pushing out frozen
pistons, but the time spent cleaning the grease out of the caliper half is
aggravating.  Try air first.  If air won't move it, then use grease.  Oh, and
to be able to use the grease trick, carry your caliper to the local auto parts
store, and purchase a grease fitting to thread into the main fluid line "in"
port.  If you have any questions, feel free to holler at me on or off list.
Worked like a charm for me, and no leaks!  If all else fails, ship your
calipers, rebuild kits, return shipping label, and a 12 pack of Michelob to
me, and i'll hook you up.

Greg
84 Spider
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