IMHO,
One drawback to compressed air is its compressibility. Pressurized air has the
capacity to launch a piston at high velocity as soon as it becomes unstuck.
Perhaps if the caliper were to be covered by a small rug, cardboard box or beach
towel... Once the first piston lets go, you'll need to reinsert it into the
caliper and clamp it in place so that the air or grease can be used to blow out
the second piston.
It's been a long time since I've had to rebuild a brake caliper, but I think
there may be a rubber "O" ring around the opening through which the fluid passes
between the two caliper halves. If any nasty organic solvents (i.e. Xylene or
xylol, Toluene, mineral spirits, etc.) are used to clear out grease, if that
method is selected, you may want to consider changing that ring too; even if it
does mean separating caliper halves. Strong organic solvents will turn rubber
into a goo with the consistency of bubble gum.
Jim
Ajhsys@aol.com wrote:
> In a message dated 1/31/00 11:56:46 PM Eastern Standard Time,
> bachldrs@swva.net writes:
>
> << I'm trying to remember how I made this. Forgive me, it's been a very long
> time. But I made up a fitting that goes where the hose normally attaches,
> with a zirk fitting on it. I just pump it full of grease and that forces
> the pistons out. You're going to clean it all up when you rebuild it
> anyway - so the grease won't hurt anything. >>
>
> - - - - - - - - - - - - - - - -
>
> I would shy away from filling a brake caliper with grease. It is not a good
> idea to contaminate brake fluid with a petroleum product, and unless you
> separate the halves of the caliper (which is not recommended) you will have
> lots of trouble getting all the grease out. Stick to compressed air.
>
> Just my 2 cents.
>
> Allen Hefner
> SCCA Philly Region Rally Steward
> '77 Midget
> '92 Mitsubishi Expo LRV Sport
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