Disc brakes ,excessive pad wear

I've completely worn out the rear pads on my Yamaha dual piston caliper .
THis has take only 2.5 k miles !
And I don't use 'em that hard .
What has happened ?
My guess is I didn't clean them and the filth on the pistons etc .. mucked
things up .
Is that it ?

Chris

 

Some riders don't use their rear brakes at all, and claim to get 50K to
60K miles out of the rear pads. I suppose the wear would be entirely
from the pads lightly contacting the rotors as they spun past...

I get 10K per set of rear pads on my Yamaha, and the same was true of
both my Suzukis. And, I used to get 10K miles out of a set of rear
brake shoes. I use the rear brakes a lot...

You could be right about road crud building up on the pistons of your
rear caliper. You might try spritzing out the crud with the cleaner of
your choice and see what happens...

Read what it says on an aerosol can of brake cleaning solvent to see if
it's ok to get that stuff onto rubber parts...

Water's bad for cleaning the crud out, it can get past the o-rings into
the brake fluid and the brake fluid loves water, it will suck water
right out of the air if it can...

Water-based alkaline cleaners are a double-whammy. The alkaline
chemical can corrode parts. The water can get into the brake fluid and
dilute it. Hot brake fluid can boil at a high temperature, the water in
brake fluid can boil at only 212 degrees F and cause steam which makes
the pistons expand and applies the brakes...

Does your brake pedal get hard to push after a few miles? You might
have *air* in the system as well as water. You may have to bleed the
air out...

Last time I cleaned out a rear caliper with sticky pads, there was a
lot of black crud and rust inside the caliper. It's a PITA to get the
second piston out of a caliper after the first piston has popped out
from pumping the brake pedal. It takes some imagination to figure out
how to block off the brake fluid port to the first piston so you can
pump out the second piston...

The difference between front brake pad wear and rear brake pad wear is
very noticeable, I get 50K and the front pads and 10K on the rear pads,
every time...

The front forks and the brake caliper mountings aren't as rigid as the
mounting of a dual-piston caliper. Rotation of the disk doesn't knock
the pads back from the rotors as intended by the designer...

IMO, the front brake pads get knocked back by the front rotors wobbling
just a tiny bit as the rider works the forks side to side when turning.
Other people will insist that the square rubber o-ring in the caliper
is what retracts the pistons and lets the pads get away from the rotors
so they don't wear...

IMO, the square o-ring acts more like a rubber ratchet than a rubber
spring, letting the pistons automatically adjust for pad wear...

 

first, is it a reasonable new bike?
the hoses are suspect. there may be a clamp on a hose that constricts the
return
of fluid from the caliper. (i've had it happen! drove me nuts).
the master cylinder may be misadjusted.
the caliper may be grunged up and the caliper is not relaxing as it should
when
you release the brakes. that's the common problem.
good luck, sammmm