1977 BMW R100RS Refinishing and Rebuilding Master Cylinder and Calipers

I refinished and rebuilt the master cylinder and calipers. You can read about how I did the work here:

This bike had the blue front calipers and the ATE front disk brakes with the drum rear leading and trailing shoe brakes. Originally, the wheels were wire spoke but a previous owner upgraded them to the later snowflake wheels.

As Purchased with Later Snowflake Wheels

As Purchased with Later Snowflake Wheels

Calipers Showing Anodized Blue Fading

Blue Anodizing on Calipers Has Faded

I rebuilt the two front calipers, the master cylinder and replaced the rear brake shoes. The blue anodized calipers had faded so I had them anodized, but this was a dismal failure. Either the shop who did the work botched it or it’s not so easy to anodize old parts. I found a paint that replicates blue anodizing. I stripped the botched anodizing and painted them. I like the result.

I replaced the lower steel brake line that goes between the caliper and the union that is inserted into the lower front fairing with stainless steel lines from Rocky Point Cycle. I replaced the rubber lines with braided steel lines with a translucent blue cover and chrome unions from Spiegler Performance Parts.

Here is the finished product. When the fairing comes back from the paint shop (soon, real soon now 🙂 ) I’ll connect the upper steel lines to the braided steel line through the bushing in the top center fairing panel.

Refinished and Rebuilt Calipers Installed in Fork Lowers

Refinished and Rebuilt Calipers Installed in Fork Lowers

Speigler Braided Steel & Rocky Point Cycle Stainless Steel Caliper Line

Speigler Braided Steel & Rocky Point Cycle Stainless Steel Caliper Line

Refinished & Rebuilt Master Cylinder Mounted on Spine Tube

Refinished & Rebuilt Master Cylinder Mounted on Spine Tube

5 thoughts on “1977 BMW R100RS Refinishing and Rebuilding Master Cylinder and Calipers

    • Hi Tom,

      The first year, 1977, BMW anodized the R100RS calipers blue. It complimented the silver/blue paint color and blue pin stripes. I suspect it pays homage to the corporate colors and the state flag of Bavaria.

      Best.
      Brook Reams.

  1. On the ATE caliper rebuild, I found the dust boots over the pistons to be a bugger to get on without tearing the rubber. I even tried 2 different suppliers of the dust boots, from reputable BMW shop.
    Finally made a wood press plate with my hole saws to press the dust boot in evenly without tearing it. One hole saw for the OD and another hole saw to make a recess for the piston so I was just pressing on the seal. Then used a C clamp to push the dust boot into place.
    Hope this helps others.

    • Hi Jerome,

      Thank you for sharing this trick to help get the dust seals on. I’ve not had too much trouble, but on this set I did have to use a drift and some light taps on the edge to gently coax the high side of the to be even in the bore and a bit recessed. The 36 mm socket helped get it pretty straight, but it wasn’t perfect so I had to “fettle it” a bit as our British twin friends would say.

      Glad you got them rebuilt and back together.

      Best.
      Brook.

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