Thanks for the info, however the entire hydraulic system, master cylinder,
servo etc has all been removed from the car for painting. I will be
inspecting the pistons later, but after 25 years I imagine they will likely
need replacing.
As to your comments regarding silicone brake fluid, I've heard the same thing
from several other people and they all recommend bleeding the system a few
times to remove the air bubbles. Many people have complained about softer
brakes or a spongy feel to the pedal after installing silicone. If the
system is bled several times as you suggested, then the "soft" pedal
disappears.
Stuart Beatty
76 Carmine
Belleville Ontario
Return-Path: <stavo56@yahoo.com>
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Date: Mon, 11 Mar 2002 02:36:16 -0800 (PST)
From: steve j daniels <stavo56@yahoo.com>
Subject: brake calipers, piston removal
To: StuBeatty@aol.com
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Hey Stuart;
Romoving the pistons from calipers can be easy, but
it's messy. Man don't try to pry them out! That's how
I started at it and I allways ended up bleeding. For
credability I have to say, I'm 46, I started working
on TR's in 1974 when I was 18 and bought a junk TR-6.
....Let's just cut to the chase. Choosing to go with
Silcone Brake Fluid is a wise dicision because it
isn't poisonous and doesn't peel paint. But there is a
concern there, which I will get back to latter.
Here's the bad news. You have to reinstall your brake
system on the car. Just bear with me here. Install the
brakes and bleed the system. (I do mean replace the
calipers and old shoes. You don't want to introduce
new shoes, they might get soaked with brake fluid.).
OK, here's why I'm telling you to do this, the brake
pedal and the master cylinder are free, built in
hydralic presses.
Now remove the brake pads from one caliper, now pump
the brake pedal about three or four times. Stop. Go
out and inspect what's happening at the caliper. Look
at the piston movement,(the point here is to use the
brake pedal and the master cylinder to drive the
caliper pistons out of their housings, but not all of
the way, if you spit one piston out, then you have an
open hydralic system and then you can't work against
the pistons in the other front caliper.).
You will see that one piston usually is willing to
move,now look around and find something to jam between
that piston and the rotor to stop it's movement, a
wrench, a screw driver, what ever. Now go back and
press hard on the brake pedal two or three times, now
go out and inspect the movememt of that other piston.
If it's moving, good; now jam that piston up, stop it
form moving, now go to the other caliper and remove
the brake pads, now start the process over again, pump
the brake pedal to push out the free piston, jam it,
then pump to get the stuck one to move. You can play
with this to get the pistons to almost fall out,
that's what you want. You can at least get the stuck
ones to move and hyper extend so that you can latter
grab them with a plyers and pull them out.
Now you will see that the pistons are shot. The chrome
plating will be pitted, you do not want to use these
again, new pistons are cheap, buy new bleeder valves
also (That is if you can get the old bleeder valves to
remove, heat the hell out of them.
Oh yes, you can split the caliper if you wish, BUT
don't loose that little o-ring that seals the halves,
you wouldn't believe how hard it is to find new ones!
I mean really hard! You can split the caliper and bead
blast the rust off of it, not sand blast, that's too
aggressive and sand blasting just might hurt the bore.
But you have the right idea here, if the calipers on
your car are original, they are not working right.
Also a suggestion, replace all of the flexable rubber
brake lines. And the Flex line to your clutch slave
cylinder; with time, all of these things break down.
And here's my cavete about silicone brake fluid, I
think it is great, but it has one property that is
kind of weird. Silicone will hold air bubbles in
suspension for quit some time. Install it one weekend,
then the following weekend bleed it again. That's all,
you will be completely safe.
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