Hi Ed,
First a couple of comments about the methods suggested so far:
a) It's true that you can clamp the free piston in place while trying to
get out the other one, but it won't necessarily work if the stuck one is
very stubborn. I still have a big bent C-clamp around here as evidence....
b) If pumping grease (my favourite approach), remember that the grease
fitting won't quite fit in the caliper. It seems like it will, because it's
27 tpi and the caliper (if it's like mine) is 28 tpi. Also, the grease
fitting's threads are tapered. Avoid wrecking your caliper threads! I went
out and bought a short brake line where one end fits into the caliper, and
on the other end I put a female to female fitting, into which I screwed the
grease nipple. It works really well - if you can hold in that one piston.
If there's room you may want to try holding it in with a vice rather than a
clamp.
If these calipers are in two halves, there's yet another method that may be
employed: split the caliper, and drill a hole in the centre of the stuck
piston. Thread the hole, and turn in a bolt, which will draw out the piston.
This is obviously a desperation measure and writes off the piston, but it
works, and you salvage your caliper. Then you get to find the right O-rings
to seal between the halves and initiate a great debate on the list about:
a) whether splitting the halves should ever be attempted,
b) the correct torque for the bolts that hold the halves together.
Happy new year!
Jim
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>From: "Edward Hamilton" <hamilton@ptd.net>
>Subject: front brake calipers -- stuck
>
>I'm In the process of rebuilding the front calipers...The pistons are
>frozen/stuck in place. I've applied 80+ pounds of air pressure to no
>avail -- would greatly appreciate some helpful hints to free them up.
>
>Ed Hamilton
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