34 BMW 1973 R75/5 Install Rear Brakes

The swing arm and rear drive are installed and you can read about how I did that here:

Next I install the rear brakes inside the rear drive, the rear brake lever and brake light switch and mount the powder coated battery box with new stainless steel Allen head bolts, wave washers and rubber bumpers into the frame.

Parts List

These are the new parts I used.
Part #                      Description                                         Qty
34 21 2 311 080      Brake shoe, Upper Rear                   (1)
34 21 2 311 081      Brake shoe, Lower Rear                   (1)
35 21 1 232 137      Wing nut brake rod, brass, polished (1)
34 21 1 230 264/5r  Brake shoes, Rear,set                      (1)
46 51 1 231 084      Battery support, rubber bumpers      (1)
007 46 R kit 007 SS*                                                         (1)
* Hucky’s Part #   Battery bracket mount kit, SS1

Rear Brake Hardware

Below are the parts that mount the rear brake shoes and the rear wheel.

Rear Brake Parts

Rear Brake Parts

At the top is the rear wheel axle (NOTE: The axle is not bent but appears so due to the angle the picture was taken at), washer and nut. The rear brake cam goes through the rear drive housing and has a felt and steel washer on the outside. The rear brake lever attaches to the splines on the end of the rear brake cam and has a steel cylinder that goes through the large holes on end of the brake lever. The rear threaded brake rod (not shown) passes through the small hole in the center of the cylinder and is secured with a brass wing nut (not shown).  The two springs are the same and attach to the shoes.

The rear brakes use different top and bottom shoes. The top shoe has angled ends (as shown by the top shoe in picture below) while the bottom shoe has one angled end (as shown on the bottom shoe in the picture below) on the side with the round cutout that goes on the fixed pivot pin in the rear drive.  The shoes I bought are from EBC so they don’t have the BMW part numbers on them.

New Rear Brake Shoes - Different Top & Bottom Shoes

New Rear Brake Shoes – Different Top & Bottom Shoes

Grease the Brake Pivot Pin and Brake Cam

I use CRC brake grease and put some on the pivot pin that is fixed in the rear drive and the removable brake cam rod and it’s cam faces.

Brake Grease

Brake Grease

Brake Grease on Rear Brake Cam Shaft

Brake Grease on Shaft of Removable Brake Cam

Brake Grease on Pivot Pin

Brake Grease on  Fixed Pivot Pin with Steel Washer Installed Inside Brake Housing

I previously put Honda Moly-60 paste on the rear drive wheel splines when I temporarily mounted the rear wheel to help prevent the drive shaft from rotating while I tightened up the drive shaft bolts. I put a bit more on as some had transferred to the splines in the rear hub.

Honda Moly-60 Paste on Rear Wheel Drive Splines

Honda Moly-60 Paste on Rear Wheel Drive Splines

Install Rear Brake Cam Rod

I attached the steel washer on the inside of the brake cam rod (non-spline end) and pushed the spline end of the brake cam rod through the rear drive.

Brake Cam and Steel Washer

Brake Cam and Steel Washer

Steel Washer On Brake Cam Rod (Toward Non-splined End)

Steel Washer On Brake Cam Rod (Toward Non-splined End)

Steel Washer on Brake Cam Shaft Inside of Brake House

Steel Washer on Brake Cam Rod Inside of Brake Housing

Then I put the felt ring over the spline end next to the outside of the rear brake housing.

Felt Dust Seal Goes on Outside of Brake Housing

Felt Dust Seal Goes on Outside of Brake Housing

Felt Dust Seal on Spline End of Brake Cam Shaft

Felt Dust Seal on Spline End of Brake Cam Rod

Then I installed the brake lever with the socket head Allen bolt on the splines. I put some anti-seize on the bolt threads.

Brake Lever Installed on Rear Brake Cam Shaft

Brake Lever Installed on Rear Brake Cam Shaft

Install Brake Shoes

I installed the top brake shoe. It only goes one way due to the difference in the cut outs on the ends.

Round Section of Top Shoe on Front Pin

Round Cutout of Top Shoe Goes on Fixed Pivot Pin

Notch Fits on Rear Brake Cam Flat Plate

Notch Side Rests on Flat Plate of Brake Cam R0d

I hung the lower brake shoe by the springs from the upper shoe and positioned it so the cam rod end was on the bottom of the cam.

Hanging Bottom Shoe from Top Shoe

Hanging Bottom Shoe from Top Shoe

Then I pushed down on the bottom shoe and used a large screw driver to guide the round cutout end onto the fixed pivot. It wasn’t seated so I used a rubber mallet and tapped it until it seated on the round pin.

Then I applied brake cleaner to the pads and cleaned them in case some grease had gotten on the pads during installation.

Install Rear Brake Pedal Assembly

The next step is installing the rear brake pedal into the frame and attaching the threaded actuator rod to the rear brake lever.

Rear Brake Pedal with Hardware

Rear Brake Pedal with Hardware

The brake pedal rotates a large threaded pivot pin that is secured with a locking nut. The top of the brake pedal has a threaded hole for a bolt and nut that contact the rear brake light switch.

I put wheel bearing grease on the shaft of the pivot pin. Note the face of the pivot pin has a zerx fitting and a hole to let grease fill the housing for the pin. I filled the hole with grease and smeared some on the shaft and put some in the hole in the frame.

Axle Grease for Brake Pedal Pivot Pin

Axle Grease for Brake Pedal Pivot Pin

Here is how the hardware go on the shaft.

Rear Brake Pivot Pin with Hardware

Rear Brake Pivot Pin with Hardware

The bolt goes through the frame, then the large flat washer goes on the bolt shaft against the inside of the frame.

Rear Brake Pedal Pivot Pin

Rear Brake Pedal Pivot Pin with Large Flat Washer

The brake pedal goes on threaded shaft, then the wave washer and finally the plastic locking nut.

The bolt and nut to actuate the rear brake light switch are screwed into the threaded hole at the top of the brake lever with the face of the bolt pointing to the rear.

Rear Brake Pedal with Brake Light Bolt

Rear Brake Pedal with Brake Light Bolt

Install Rear Brake Light Switch

The rear brake light switch mounts with two screws on the bracket inside the frame. There is a rubber cover for it, but I will put that on after I get the wiring harness installed and hooked up to the rear brake light switch.

Rear Brake Light Switch

Rear Brake Light Switch

I adjusted the bolt in the brake pedal until the pin in the brake light switch just fully extended when the brake pedal was up. When you push down on the brake pedal, the bolt moves forward and the pin retracts into the switch turning off the brake light. I’ll make final adjustments to it when the electrical system is installed.

Brake Light On

Brake Light Off

Brake Light Off

Brake Light On

Install Battery Box

I installed the powder coated battery box with some new stainless steel Allen head bolts and wave washers.  I put in new 10 new rubber bumpers into the holes in the box.

Battery Box Installed

Battery Box Installed

Here is the condition of the battery box at the start of the project. Significant improvement.

Battery Box Rust

Battery Box Rust at Dissassembly

Final Product

Here’s the bike with the rear brakes installed and rear wheel mounted.

Rear Brake Pedal and Wheel Installed

Rear Brake Pedal and Wheel Installed

Final Result

Final Result

 

8 thoughts on “34 BMW 1973 R75/5 Install Rear Brakes

  1. Pingback: 1973 BMW R75/5 Rebuild: Rear Brake Installation | Motorcycles & Other Musings

  2. Sir . . . I’m reassembling the rear brake, and my question is in regarding the removable shaft and its metal washer. It appears that you did not put the metal washer on the shaft before installing the shaft (ie., so no washer on the inside) but rather saved it for the outside, after the felt washer.
    When I disassembled mine, the metal washer was on the inside. Further, I tried it both ways – upon reassembly. I found that if I put the metal washer on the inside this made the shoes line up perfectly with the final drive body. If I did not use the metal washer on the inside, the gap between the shoes and the final drive body was not even. In other words, using the metal washer on the inside appears to be correct.
    Any thoughts on this?
    Thanks. I’m working on a 1972 R75/5 toaster with a manufacture date in late 1971.

    • Hi Bill,

      Thank you for stopping by and reading this write-up. Simply stated, you are correct and what I did was incorrect. I made the changes in the parts order and updated the page with correct pictures and text. Thank you so much for catching my error.

      Best.
      Brook Reams.

  3. You’re quite welcome . . . and thanks.
    I thought I was correct but after seeing your description wasn’t sure. Neither the manuals I have nor anything online that I could find made it perfectly clear to me which way is correct. The exploded diagrams of the rear end show the parts but not the order of assembly.
    You do a wonderful service with this documented overhaul. And . . . your completed project is beautiful.
    -Bill

  4. Hey Sir,

    So I have looked high and low on the web for the EBC brand break shoes. Who did you order yours from? I live in nowhere KS so my choice of in-person dealers is limited.

    Thank you!

  5. Did you polish, powder coat or paint the brake pedal? My 71 r60 is now completely disassembled and thanks to your website I might be able to get back together.

    -Reed

    • Hi Reed,

      I cleaned it and then used “000” steel wool to make it shine. Then I applied AutoSol aluminum polish.

      Best of success on your R60 project.

      Best.
      Brook.

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