Carl,
Since the pistons don't contact anything except the seal in the grove, ultra
smoothness shouldn't be a factor. Actually, the pistons only travel
fractionally when the brakes are applied; mostly just the seal flexes. When the
brake pedal is released, and the pressure is gone from the piston, the seal
returns to it's original shape pulling the piston back away from the rotor with
it - this is what prevents the pad from remaining in close contact with the
rotor. At least this is what I've been told by a mechanic that's been in the
business for a long time.
Dennis
'61 TR3A, still apart, but making progress
Michael Marr wrote:
> Funny you should ask this question - I just installed two of the Moss
> stainless pistons in one of my calipers. I certainly did not measure the
> difference in surface finish, but they looked very comparable. Some of the
> chrome had come off the old pistons, right about where the seal does its
> work, so I decided to give the SS pistons a try. No idea about the
> longevity of seals yet, but I bet they will last quite a while. Its not
> like the pistons are in constant motion, after all.
>
> -----Original Message-----
> From: CarlSereda@aol.com <CarlSereda@aol.com>
> To: triumphs@autox.team.net <triumphs@autox.team.net>
> Date: Tuesday, September 07, 1999 2:03 PM
> Subject: Chromed or Stainless Brakes Better?
>
> >
> >Hi List,
> >I want to replace the four pistons in my TR4 brake disc calipers as they
> are
> >35 years old and well rusted outside the bore seal and rust is working
> inward.
> >I never saw chrome look so good (on the intact part) and imagine that is
> why
> >the seals works so well. I am a little dubious of the finish on the
> stainless
> >pistons (can't imagine it is as smooth as this chrome).
> >Anyone compare the two pistons (chrome vs stainless) side by side?
> >In another 35 years I will be 78 (and maybe too rusty myself to drive) so I
> >am tempted to go chrome for the best sealing properties and they're a
> little
> >cheaper too.
> >Any counter opinions on this? And are some vendors known for better pistons
> >than others?
> >Carl
> >'64 TR4 since '74
|