1999 R1100RT Rear brake master

[Gregory]

Hi all. I suspect that my brake rear master is failing. I'm going through the process of checking the pads and bleeding the lines to see if that firms up the pedal. TBT. Is the rear master rebuildable and if so where can I get the rebuild parts? I checked Beemer boneyard. TNA. I replaced all the brake lines with braided stainless so that's all good. Thanks in advance. Gregory

 

[m_stock10506]

If it really is a bad rear MC, look for used/salvage parts. I have a LOT of miles on my 1100RT and still have the original MC. I would bleed the rear line, refilling the reservoir at least 3 times. Then, if you can get a firm brake pedal, push it so the brake is working and tie it down in place and leave it overnight. The rear circuit is difficult to get fluid moving properly once the lines are opened and get air, because the ABS module is the highest point. You'll have a hard time getting the pedal to start pushing fluid. I have had success by reverse filling from the caliper to the MC, and also by applying a vacuum to the circuit at the caliper until you feel the pedal moving fluid.

 

[fbt80]

Agree, new rear masters are crazy expensive: https://www.euromotoelectrics.com/category-s/2936.htm
If that's the issue buy used...but make sure you have no leaks from any of your lines, install a speed bleeder on the rear caliper if you haven't already and try the "reverse filling" as m stock said...and if you think your ABS units still has air in it, then here's the best video on flushing and filling your ABS I've seen. I used it when I switched to braided.

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[Gregory]

Thanks for the reply's. I did the same system bleed when I went to all stainless braided too. Also went with speed bleeders front and back. The ABS on my 99 is not integrated so that really simplifies the the bleed process. I found a new 12mm Brembo rear master for $89.00 without the pushrod linkage, which I don't need anyway. That's really cheap. Thanks again

 

[m_stock10506]

install a speed bleeder on the rear caliper if you haven't already and try the "reverse filling

Yes, I have speed bleeders on all three calipers. They make brake bleeding quick and easy.

I’ll offer one correction here. Keep the standard bleed screws available somewhere easy to find. The check valve on a speed bleeder will prevent fluid from going in the reverse direction. That’s exactly what it’s designed for. If you want to reverse fill the brake circuit, you’ll have to install the old standard bleed screw to do that.

 

[fbt80]

Yup, speed bleeders for top down fill, but stock screws if you try the reverse.