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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: herseyb on May 23, 2020, 08:19:59 PM

Title: rear brake whack - what next?
Post by: herseyb on May 23, 2020, 08:19:59 PM

80,000 mile K1100RS ABS rear brake started getting hot a couple months ago.  Started pinging after riding around the block and the dust boots melted to the pistons.

I have tried:

Flushing fluid (negatory)

Cleaned pins which were gunky and rusty. (Negatory)

Replacing hose from resevoir to MC - all other hoses had been replaced with braided lines (negatory)

Measured lateral runout with dial caliper, .003 max deflection, within spec.

I just finished rebuilding the caliper and putting new pads in, since the old pads had not worn evenly.

Now I am spinning it around by hand and I still hear the pads kissing the disc for about 1/3 of travel, same spot each time after applying brakes.  Same pattern as before rebuilding the calipers.

Got the dial indicator back out, still seeing minimal lateral error, nothing beyond spec.

Should I try bedding these pads in or is that a false hope? 

Only thing I haven't done is fux with the master cylinder.

Time for a new master cylinder/ MC rebuild?

upgrade to comprehensive insurance and ride it around hoping it spontaneously combusts?

Title: Re: rear brake whack - what next?
Post by: Laitch on May 23, 2020, 10:03:18 PM

Do this then follow EBC's simple bedding-in guidelines here (https://ebcbrakes.com/articles/motorcycle-bed-in/). The steps to take are to check the brake pedal linkage to verify that it's set correctly, then determine if the master cylinder piston is retracting. My moto's cylinder has a helper spring but the piston was retracting ok before I replaced the missing spring. If the piston isn't retracting, disassembly and cleaning would follow. A rebuild might not be necessary. This is a symptom that drags owners down the rabbit hole. Don't let that happen to you.  :laughing4-giggles:
https://www.youtube.com/watch?v=QjKJKt9DAT4 (https://www.youtube.com/watch?v=QjKJKt9DAT4)
 

Title: Re: rear brake whack - what next?
Post by: herseyb on July 22, 2020, 09:50:17 PM

still touches the disc during a portion of the cycle after putting new seals in the caliper, but it no longer gets hot.

success and out of the rabbit hole!  vrrrrmmmmmmmmm!