1983 BMW R100RS Install Rear Brake System

I’m converting this RS model to a RT. The only difference in the brake system is the length of the hose from the front master cylinder to the front brake line splitter underneath the gas tank as the RT handlebars are wider so that hose is longer. The rear brake system is the same on both the RS and RT models

I previously rebuilt the two front and one rear calipers and rebuilt the rear master cylinder. The front master cylinder was so badly corroded that I replaced it along with the entire right handlebar perch. I also installed the three disk brake rotors on the newly powder coated wheels. You can read about how I did that work here.

Here is the documentation of how I install the rear brake system and a short video summary of the procedure.

VIDEO: 1983 BMW R100RS/RT Install Rear Brake System

The master cylinder in on the right side while the rear brake caliper is on the left so there is a long steel brake line between the master cylinder and a bracket on the left, lower frame gusset where the flexible brake hose from the caliper attaches to the steel brake line. That’s a long run of brake line and I use my “Air Zapper” to help pull the air out of the line.

"Air Zapper" Vacuum Brake Bleeding Parts

“Air Zapper” Vacuum Brake Bleeding Parts

I finished up bleeding the rear brake system by pumping the rear brake pedal and opening and closing the caliper bleed valve to get the last bit of air out of the system. I now have a solid rear brake all set to stop.

Rear Caliper Mounted And Ready To Stop

Rear Caliper Mounted And Ready To Stop

So next up is installing the front brake system.

2 thoughts on “1983 BMW R100RS Install Rear Brake System

  1. Very well explained as usual. I do not have a disc brake on the rear of my airhead but I can always use a video and well intentioned and thought out procedures that don’t hide our inadequacies.Thank you for all that you do for airheads everywhere.

    • Kit,

      Thanks for the kind words. This is the first rear disk I’ve worked on, so it’s been a good learning experience.


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