Don:
This is just a swag, so don't panic. Any chance the pistons or
seals are the
wrong ones? There were Metric and English calipers, and I *presume* that
the pistons
likewise would be English and Metric. In any event, Moss lists two
different pistons
depending on when your car was commissioned. Likewise, the earlier
English calipers
had two different, non-interchangeable sets of seals. Another
possibility is that
the brakes were swapped at some point during the car's lifetime, and you
now have
metric instead of English, or vice versa. Looking at the letters at the
end of the
casting number on the calipers gives you the tip-off. English = B,
Metric = BP.
My car is later, and had the metric fittings. When I replaced my
pistons, the were
a firm, non-binding press fit by hand after I lubed the seals with DOT
5. Interestingly,
my new pistons were black instead of steel colored. I presume this was
some sort of
passivation to prevent rust, but that is just a guess. My original
pistons were
rust colored =:-o
You are correct, the pads will drag lightly on the rotors even
when everything
is new. Current disk brakes are specifically designed to "lift" the pads
from the
rotors when not in use, to save fuel.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Don Malling
Sent: July 10, 2005 12:30 PM
To: 6-Pack; triumphs@autox.team.net
Subject: New caliper pistons fit tight.
How tight should the new calipers be in the cylinders. Mine are very
tight. Almost can't even turn
them in the cylinders. I bead blasted the cylinder cavity so I know the
rubber seal groove was very
clean. Hmmm I put some of that red brake lube in the groove. Maybe that
was a mistake. I'll clean it
out. I just had to remove one because I put it together w/o the dust
boot. It was harder to get this
new one apart than it was the old rusty ones.
Anyway should I be able to insert and withdraw the pistons easily -- by
hand w/o tools or do they
fit tighter than that? How tight is too tight? I guess I don't have a
feel for how powerful the
hydraulic system is.
Even if the hydraulics are strong enough to push the piston out, what
causes the brake pads to pull
away from the rotors when the brake pedal is released? These pistons are
so tight, I would imagine
they would drag on the rotors.
Thanks,
Don Malling
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