K11 Owners Group

ljjohns

Tomorrow's wrenching includes a rebuild of the front master cylinder on the 95K11 among other things. After installing new pads while installing a "new" set of front forks, the MC started leaking and so I've got the rebuild kit from beemerboneyard.

I'm aware of the need to either replace or re-anneal the copping washers.

What I'm still trying to puzzle out is the flow of brake fluid from the MC to the brake pads: does it go through the ABSII controller? So when we recharge the brake fluid in the master cylinder, should we bleed from the controller?

BTW, I do have Phil's write up on the process, but he's in Morenci and I'm here.

Any other helpful hints would be appreciated.

Larry Johnson
El Paso TX
_________________
1993 K1100LT (Washington)
1995 K1100LTSE
1996 K1100LTSE (parts)
2003 K1200LTC
1991 K75RT

Flying Duck · Posted: Fri Mar 04, 2011 5:54 pm Post subject:

Chances are you don't need a rebuild. One time when I changed the pads on the RS pushing the caliper pistons out so the new pads would fit on the rotors made the master leak because of the pressure in the system from pushing out the pads. That was 15k or so ago and my master cylinder has been fine without a rebuild or any maintenance other than annual bleeding.

I just replaced the front pads on my LT today. What I do now is do the left one first and put it on the bike. Then I mount it on the fork and rotor, put a hose on it's bleed valve and open it up a bit. That way the pressure from spreading the right pads goes out the left bleed valve and isn't forced back up to the master cylinder.

Bleed at the ABS first, then calipers.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

ljjohns · Posted: Fri Mar 04, 2011 6:18 pm Post subject:

Drake: I'd seen your comment on that phenomenon, and so that initially gave me hope, but the pad replacement was four weeks ago and the leakage still continues intermittently. So we'll do the rebuild--I've got the part.

But when and if I ever get to the parts bike, whose major problems are the fuel pump system (missing) and the front MC (in parts), I'll follow your advice for working the front brakes.

Thanks.

Larry
_________________
1993 K1100LT (Washington)
1995 K1100LTSE
1996 K1100LTSE (parts)
2003 K1200LTC
1991 K75RT

Number 6 · Posted: Fri Mar 04, 2011 6:36 pm Post subject:

It is a common failure of the K11. Be aware that often the BTR screw of the brake lever axis is stuck (glued) and difficult or impossible to unscrew. If you do not manage to unscrew it, change the whole master cylinder for a used R1100 or R850 master cylinder, it is exactly the same but it has a specific surface treatment that make it much more durable. I just did that on my bike and it cost me half the price of the rebuild kit.

Now if you do manage to get the lever out, you'll have to clean the cylinder with some fine sandpaper using brake bluid, and not going in the direction the piston goes but at 90°, in rotation (not sure it is clear).

Then yes you'll have to bleed the controller first (rear bleed screw is the front brake, very logical Wink

) then the callipers. Another method is to push brake fluid from the callipers to the master cylinder, that way you just need to bleed the calliper (because you'll introduce some air too) but not the ABS, which is what I did.
_________________
I am not a number, I am a free man.

94 K1100LT

Flying Duck · Posted: Fri Mar 04, 2011 7:16 pm Post subject:

The pivot for the brake lever isn't that hard to get out once you get the knack of it. Unscrew it all of the way and the head remains more or less flush but if you keep some sideways pressure on the socket you can wiggle it out.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

Flying Duck · Posted: Sat Mar 05, 2011 10:12 am Post subject:

BTW: Mine took several hundred miles to repair itself. I did it visiting my dad in CA about a day and a half before I'd planned to leave. I didn't have the time to deal with it so I figured I'd have to take care of it when I got home.

To the extent safely possible, I minimized front brake usage on the way home and at every gas stop on the way home I'd take off the little plastic cover and clean things up with a paper towel. After about 600-800 miles or so it stopped leaking so by the time I got home it was fine and has been fine ever since.

In parting bikes and stuff I've found that many times master cylinders don't need to be rebuilt or replaced. Many times there's just crud in there so I take the MCs apart and clean everything up. Of course if the bore is pitted then it goes in the trash or if the seals are scraped up then it needs a rebuild.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE