Rear brake resivoir.

Pete wrote:

>I think I'll have to replace the caliper since idont think that diaphragm
>was on there
>right. Am I right in thinking that the flat lip on the diaphragm goes on the
>top of the
>reservoir to seal out air and water?

Yes, the top of the diaphragm acts as a seal to keep air and water out of the
reservoir and the diaphragm expands as the brake pads wear.

The lower end of the brake system is, of course, the caliper.

The square o-ring is all there is to keep water out of the caliper, and water
will get past it and the piston will rust or the o-ring will wear and little
bits of rubber will build up inside the caliper and it will jam up, causing
the rotor to get very hot.

Also, the clearance between the piston and the aluminum caliper is very small,
maybe 1/1000th of an inch, so it's difficult to line the piston up when re-
installing it. When I did a brake job on an old Datsun, the previous owner
had forced the piston back into place with a screwdriver and the piston would
stick because it was very slightly bent. I had to replace that piston.

I replaced the fluid on one old motorcycle that hadn't had a fluid change in
16 years. The rear
brake would make a horrible groaning noise when applied.

So, I removed the caliper and pumped the brake pedal until one of the two
pistons popped out.

Then I was faced with the problem of how to get the other piston out.
Fortunately, the banjo bolt
that connected the brake line was centered on the piston and I was able to
remove the banjp bolt and stick a drift through the hole and gently tap on it
and drive the stuck piston out that way.

Most calipers are not constructed with banjo bolts on the side though and
sometimes a mechanic has to use a c-clamp to hold a piston that moves easily
while he pumps the other piston out.

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