Rear caliper rebuild, rotor wear

[Miles Long]

This one's for all, but Mr. Morley may have a particular interest-
I'm now working on my 3rd, maybe 4th, I can't remember, set of rear brake pads, on my '03 Max. The first two replacement sets were EBC FA 88(organic), the set in use now are O.E.M.($$$!), because that's all the dealership carried where I purchased them(I was travelling at the time).
This excessive(?) wear started from the get-go, as I recall I had to put in the first set of pads when the bike had less than 20,000 kilometers showing. Now at 74,000 k.
I have never used the rear brake excessively, and until recently have considered this "normal" wear. Now, I don't think so, because I've noticed recently that the rotor is quite hot, even though I haven't used the rear brake to stop. I adjusted the foot lever to make sure I had maximum play before engagement, but the hot rotor persists.
Sean, the rotor that we both thought to be O.K., is now down to the minimum recommended thickness, 7mm. Wear on both sides has been even, however. As I had mentioned to you when I visited your shop, I had checked the pistons just a week before, and both retrackted O.K., with the help of channelocks and rubber for protection.
My questions, for everybody that have done brake maintenance -
-Is this normal wear for the rear brake?
-Is the even pad and rotor wear indicative of a problem with the master cylinder, and or both master and slaves?
-Can the calipers be disassembled(pistons removed, bores cleaned) and reasembled WITHOUT having to install new seals and O-rings?
- Where is the best(i.e., less expensive) place to purchase a new rotor?
Thanks in advance, Miles

 

[one2dmax]

You've got a lot of miles on the brakes and there will be wear. 1, from the debris that collects as you roll down the road and 2 from the friction created by the pads themselves (metallic pads have tiny hard spots of metal in them).

If the pads aren't retracting just slightly by themselves then that might indicate they are sticking out and causing more friction and wear then they should. You should be able to remove the pistons and seals, clean up the bores, polish the pistons, and reassemble without getting new seals. Note that the outer dust seals for the pistons will probably look like hell but should still work fine.

I've got used rotors for $50 but some of the guys doing the busa upgrade can maybe sell you the right front rotor (85-92 front right rotor is the same as all years rear rotor). I've personally never replaced even a crappy looking rotor for thickness concerns - only due to damage or warpage where you get pulsing brakes.

last thing to check is to make sure you aren't even just barely touching the rear brake lever and that the fluid isn't over-filled.

Sean

 

[Miles Long]

Thanks Sean. I will pop the pistons out and clean everything up. Hopefully that will solve the hot rotor problem. I'll most likely contact you during the winter for a new rotor, and maybe some other goodies as well. Take care.
Miles