I rebuilt my calipers last spring, and I have done this previously in other
cars. I made a thin piece of plywood that fits over a piston. I hold it in
place with a c-clamp. I used a rubber washer on the end of the air nozzle
and pressed it against the hole where the brake hose attaches. A quick push
on the trigger and the loose piston moves out. I put a shop rag on top of
the loose piston in case it pops all the way out of the cylinder. It won't
go far because the other side of the caliper is in the way. If you happen to
have a finger stuck in between the two pistons when you add the air, shame on
you. Expect a very sore finger, probably broken.
For the second side, you can put the properly sized piece of plywood over the
open cylinder and clamp it down. This should be tight enough for the air to
do it's work. Then put in the shop rag and apply air.
Allen Hefner
SCCA Philly Region Rally Steward
'77 Midget
'92 Mitsubishi Expo LRV Sport
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In a message dated 2/1/00 11:28:23 AM Eastern Standard Time, microdoc@apk.net
writes:
<< One drawback to compressed air is its compressibility. Pressurized air has
the
capacity to launch a piston at high velocity as soon as it becomes unstuck.
Perhaps if the caliper were to be covered by a small rug, cardboard box or
beach
towel... Once the first piston lets go, you'll need to reinsert it into the
caliper and clamp it in place so that the air or grease can be used to blow
out
the second piston.
It's been a long time since I've had to rebuild a brake caliper, but I think
there may be a rubber "O" ring around the opening through which the fluid
passes
between the two caliper halves. If any nasty organic solvents (i.e. Xylene or
xylol, Toluene, mineral spirits, etc.) are used to clear out grease, if that
method is selected, you may want to consider changing that ring too; even if
it
does mean separating caliper halves. Strong organic solvents will turn rubber
into a goo with the consistency of bubble gum. >>
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