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Re: Caliper Piston Stuck

To: Ct54531@aol.com
Subject: Re: Caliper Piston Stuck
From: Alan Myers <reagntsj@ricochet.net>
Date: Sun, 07 Feb 1999 19:55:16 -0800
Cc: Triumphs@autox.team.net
Organization: Coldwell Banker Residential Real Estate
References: <1565f90e.36be277c@aol.com>
I read something the other day, maybe on this list, that I plan to try
with stuck & stubborn caliper pistons... go to local auto parts store
with one of the pistons that's already out of the caliper and fit up one
of those replacement "freeze plugs" that are basically a round humk of
rubber with a couple washers on either side and a bolt thru the middle.
As you tighten the bolt, it expands the rubber. Just talk guys at the
auto shop into finding one that fits loosely into the hollow part of the
piston.

I figure I can rig a short handle out of flat aluminum or steel to put
under the bolt to make it easier to use for this purpose. Slip it inside
the hollow part of the piston that is stuck in the caliper, tighten
until it has a good grip, then carefully work the piston out of the
caliper. 

I am not sure what you are refering to as a Blaster, but if it's
compressed air, IMHO it's not a very good idea to use on TR calipers,
because they are "split" and have an o-ring/seal between the two halves
that could be damaged from the air pressure. In fact, there are warnings
in the manual about not cleaning the caliper assembly with any strong
cleaners that might get into the gap and damage the seal.

If you are definitely going to replace the piston, you can use an old
screwdriver to lever the piston out. Use some small scraps of wood to
protect the caliper itself from damage. Start on one side, then the
other, working your way around gradually. It will almost surely damage
the lip of the piston that the dust boot slips into, but if it's slated
for replacement anyway, who cares. You must be very careful not to tilt
the piston too much so that it would scrape and damage the cylinder
wall. 

In desperate cases, I've even used a small scrap of wood shaped like a
chisel under the lip of the piston and tapped on the wood with a small
plastic mallet to get it started. The same caveats about trying to keep
it coming out pretty straight apply.

If the car has been sitting a long time, it may also be useful to drip
some brake fluid around the outside edge of the piston lubricating dried
out seals and helping it come out easier. Also, sometimes you can break
loose a stuck piston by pushing it into the caliper slightly, then
working it back out. That can be risky, though, you may end up worse of
than when you started!

Good luck and keep in mind that the only thing more "exciting" than
trying to get the darn things out is trying to get them to go back in!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L





Ct54531@aol.com wrote:
> 
> List:
> 
> I am now working at freeing the caliper pistons for my 65 4A and have had some
> success. One of the four won't budge, however. Given that I am going to
> replace the pistons and seal, is it okay to hit it with Blaster. Once again, I
> seem to remember a caution against that. (Someday I may actually remember
> something instead of just seeming to.)

-- 
MZ

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