K11 Owners Group

N41EF

Again, I turn to the brain trust here. Did the 16.5k service this weekend, and replaced front and rear brake pads trying to fix a pad squeel on the rear. My rear pads were worn, very very thin, but when I started to bleed the rear I found the master cylinder empty. I had flushed the fluid less than a year ago and still had a decent pedal feel. I checked the ABS lines, no leaks on the rear caliper, and finaly found a leak on the rear master cylinder at the front, where the boot goes on.

So A quick look finds no used master cylinders and it's either $60 for a rebuild kit or $130 to buy a new one. Has anyone rebuilt one? I've put kits in caliper before, but never a master cylinder.

After filling it, and bleeding it/flushing it I have a good pedal again, but this needs to be fixed soon. HM is coming up....
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2014 R1200RT Water Cooled
2001 R1100S Light
1993 K1100LT. Nissan Ice Blue.(Gone)

Inge K. · Posted: Sat Feb 14, 2015 7:29 pm Post subject:

First check the bore, if it looks OK...it shouldn't be a problem to use a repair kit.

Scott_Anderson · Posted: Sat Feb 14, 2015 9:45 pm Post subject:

Not saying it's right or wrong, you may be able to just "clean" the bore with some fine steel wool and re-assemble.
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Ride safe.

1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
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"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)

mw074 · Joined: 17 Feb 2015 Posts: 9 Location: Michigan

Rebuild it. Cheaper and as good as new.

N41EF · Posted: Sat Feb 21, 2015 9:36 pm Post subject:

I bought a rebuild kits from BeemerBoneyard. Will tear it down, clean the bore, and install the rebuild kit. Not sure about how to prime it other than just fill the resevoir and pump it.
_________________
2014 R1200RT Water Cooled
2001 R1100S Light
1993 K1100LT. Nissan Ice Blue.(Gone)

Inge K. · Posted: Sat Feb 21, 2015 10:16 pm Post subject:

When you have cleaned the bore, check that both openings from the reservoir is open.
If the smallest one get clogged the fluid won't return to the reservoir, and the rear calipper will get awfully hot.

N41EF · Posted: Sun Mar 08, 2015 8:22 pm Post subject:

Did the rebuild today. I left the resevoir line connected and removed the MC from the foot peg bracket. The bellows was full of what looked like grease, and the bore on the end of the piston where the small piece that rides on the brake arm was also grease packed. The grease was full of sand, dirt and trash, cleaned it out with q-tips and did not put any back in since the Clymer didn't talk about it.

The bore was good, no scratches or pits, only damage was to the two cups on the old piston. I soaked the piston in brake fluid and twisted it and it slid in easy. The new boot was very tight to get on, should keep any dirt and such out. It's nice and dry so should be easy to see if it's leaking again.

Used a mighty-vac suction gun to flush it to the ABS unit, then to the rear caliper. It took alot get the MC flushed, but I have a firm brake pedal.

Thanks for the help here, was pretty easy once I got it off.
_________________
2014 R1200RT Water Cooled
2001 R1100S Light
1993 K1100LT. Nissan Ice Blue.(Gone)