1983 BMW R100RS/RT Install Front 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 manifold underneath the gas tank (RT: Part# 34 32 1 241 565; RS: Part# 34 32 1 241 564). Since the RT handlebars are wider, that hose is longer. The rear brake system is the same on both the RS and RT models.

Here is a link to the documentation of how I do this work.

And this is a short video summarizing the procedure.

VIDEO: 1983 BMW R100RS/RT Install Front Brake System

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 link to showing how I install the rear brake system.

I opted to use the mechanical front brake switch that mounts in the right perch instead of the original brake fluid pressure switch that mounts on the rear of the front brake manifold under the gas tank. The hole in the pressure switch can trap an air bubble making it more difficult to bleed the brakes.

I plugged the rear hole in the front brake line manifold where the front brake light pressure switch mounts.  McMaster-Carr sells a plug with copper crush washer that’s perfect for this.

McMaster Carr Stainless Steel Plug With Copper Washer

McMaster-Carr Stainless Steel Plug With Copper Washer

Stainless Steel Plug Installed In Front Brake Line Manifold Hole For Pressure Switch

Stainless Steel Plug Installed In Front Brake Line Manifold Hole For Pressure Switch

I now have brakes and the bike is getting pretty close to being finished.

Front Brake Line Manifold Connections

Front Brake Line Manifold Connections

All Done-Left Side

All Done-Left Side

All Done-Right Side

All Done-Right Side

3 thoughts on “1983 BMW R100RS/RT Install Front Brake System

  1. I have a 70’s R50. It’s in excellent shape. It wont gi over 50 miles an hour. When I shift into top gear and twist throttle it just stays at 50 mph. It’s almost like there is a governor on it. I havent has the chance to begin to check carbs or cables and timing yet. I figured I would ask before I started. Thanks in advance.

    • Hi Paul,

      You know the history of your bike better than I. If this behavior recently started, what did you do before it behaved this way? That’s were to start diagnostics.

      The items that you might check include:
      – Carburetors
      * Fuel level in float bowl
      * Float moves freely
      * Obstruction in fuel lines
      * Main jet sizes match and are size BING/BMW says they should be
      * Throttle linkage fully opens and slide fully retracts
      + Throttle cables are not hanging up
      + Slide moves freely
      – Fuel Tank
      * Petcock filters are not plugged
      * Gas cap vent is not plugged
      * Rubber valve inside petcocks is not damaged, or got crud in it.
      – Ignition
      * Timing goes to full advance around 2000-3000 RPM
      * Plug wires aren’t shorting out, are tight
      * Spark plug caps aren’t shorting out
      * Coils aren’t cracked or damaged
      – Brakes
      * Make use front and read brakes aren’t dragging
      – Engine
      * Muffler not plugged with mouse nest, or anything else
      * Cylinder compression is good
      * Leak down test shows valves, rings not leaking

      That’s some of what comes to mind to help diagnose what’s causing the lack of power.

      I hope this helps.

      Best.
      Brook.

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