Paul,
My experience is that you don't use a pounding force on the piston. It is a
tight fit so the piston has to keep centered in the bore. Your hands should
have sufficient force to install the piston if it is centered and
lubricated, but you have to keep the piston centered. If you use a hammer
it is easy to get the piston off center and damage the piston, seal and or
bore. The easiest method I've found if you can't push it in by hand is to
use a C clamp or one of those ratcheting wood clamps. Put something like a
piece of wood over the piston and slowly press it into place. As Darrell
said, be sure to lubricate the piston and seal with brake fluid to make the
process go easier. I also open the bleeder so air can escape and not cause
resistance unless the brake line is already removed. Also, no such thing as
a dry fit with the piston and O ring in place. Not a good idea to assemble
the disassemble as it presents a good chance to damage the seal each time.
That said, it is difficult for the piston to catch the O ring as the end of
the piston is slightly rounded to prevent damage and ease assembly.
I can't remember the exact design of the TR3 dust boot, but I believe you
have to install it in the bore before installing the piston. It fits in a
groove at the top of the bore and can't be installed after the piston is
installed.
IMHO no way I would try to adjust the size of the O ring, especially on a
grinder. Way to aggressive and uneven - will definitely cause a problem.
Should be no reason to adjust it anyway.
Good luck
Pete
-----Original Message-----
From: owner-triumphs@autox.team.net
[mailto:owner-triumphs@autox.team.net]On Behalf Of TR250Driver@aol.com
Sent: Tuesday, November 15, 2005 11:50 AM
To: dorpaul@negia.net; triumphs@autox.team.net
Subject: Re: TR3 BRAKE DESPIRATION!!!!!!!!!!!
In a message dated 11/14/2005 11:29:37 PM Eastern Standard Time,
dorpaul@negia.net writes:
> . What is the right amount of resistance encountered when the piston is
> pushed into it's caliper hole? (that is, with a trial fit with only the
> piston and O-ring in place). It doesn't seem to me that the brake piston
> would slide out correctly if one has to tap the piston down with a rubber
> hammer.
> 2. Is it a NO-NO to even think of pressing the O-ring up against a running
> shop grinder in order to uniformly take 1/16" off its diameter? (I'll have
> to admit I did this because I had a few extra seals!)
> Thanks,
> Paul Dorsey
>
Paul,
I have done quite a few rebuilds over the years to various TR calipers. As
I
recall the piston will normally require some force to slide into the hole
with a new seal. Don't forget to lubricate the seal with brake fluid so it
will
slide easier. I would say what you describe is normal and not cause for
concern. Grinding a seal would be a bad thing IMHO.
Darrell
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