1977 BMW R100RS Project: Remove & Repair Bodywork

I wrote up how I removed all the body work on this bike. I discovered a broken upper fairing bracket that was held on with only a hose clamp. There was a broken plastic boss with a threaded insert and numerous cracks and other damage to the fairing panels and side covers. I repaired all of them except for the top center panel that goes around the headlight. The damage was significant with a multitude of hairline cracks and I opted to buy a used panel rather than risk cracks showing up in the paint work after I tried to repair it.

Here are links to the write-ups.

I’m ready to start removing the forks and working my way towards the rear as I strip it down to the frame. Then I can see what other surprises are in store ūüôā

Here are a couple pictures from the write-ups.

Screen Damage So I Will Replace It

Windscreen Damage

Drill Bit and Hammer Removing Center Pin of Windscreen Rivet

Tapping Drill Bit with Plastic Hammer to Drive Center Pin Out of Windscreen Rivet

Windscreen Removed

Windscreen Removed

Carefully Drilling Inside of Dash Rivet

Carefully Drilling Inside of Dash Rivet

Dash Removed From Fairing Panels

Dash Removed From Fairing Panels

Broken Upper Fairing Bracket Steering Stem Mount

Broken Upper Fairing Bracket Steering Stem Mount

Fairing Panels Removed

Fairing Panels Removed

Headlight Panel Badly Broken

Headlight Panel Badly Broken

Headlight Panel Lower Right Corner Badly Damaged

Headlight Panel Lower Right Corner Badly Damaged

Upper Side Panel with Large Crack

Top Left Side Panel with Large Crack

Top Side Panel Cracks Routed Out with Dremel Tool

Top Left Side Panel Cracks Routed Out with Dremel Tool

Top Side Panel Plast-aid Repair

Top Left Side Panel After Plast-aid Repair and Sanding

Bottom Side Panel Repair to Brass Insert Boss

Bottom Right Side Panel Repair to Brass Insert Boss

Bottom Side Panel Brass Insert Final Hole Size

Brass Insert Final Hole Size-5/16″

Bottom Side Panel Brass Insert Test

Testing Integrity of Boss & Brass Insert Repair

1977 BMW R100RS Project: Getting Started

I picked this bike up in April 2016. Finally, on September 1, I got started on it. I had to finish up work on the 1975 R75/6 “S” update and completed that in July. I’ve put about 600 miles on that bike and its running well. You can see all the work I’ve done on the R75/6 here:

I wrote up a project page and added my build plan. You can find these here:

My goal is to complete the build by September 1, 2017 so I can ride the bike to the 40th anniversary get together in Pennsylvania later in September.

I will be posting a write-up on how I repaired the numerous cracks and broken parts on the fairing panels soon.

Here’s what I brought home, and what it looks like in the shop now. ¬†Progress is being made.

"10 Foot" View

“10 Foot” View

"10 Foot" View

“10 Foot” View

"10 Foot" View

“10 Foot” View

10 Foot View

10 Foot View

Body Work & Wheels Removed

Body Work & Wheels Removed

1975 BMW R75/6: Installing Wiring Harness

I documented installation of the main wiring harness on this project and posted it here.

I made a short video to show the routing I used and where the front turn signal, neutral switch, voltage regulator, starter relay, coils, Dyna III electronic ignition, oil pressure switch, neutral switch and rear tail light/turn signal wires go.

Video Link:
–> https://www.youtube.com/watch?v=Wq_ZDRPHVeY

It includes links to two other write-ups: The first describes the wiring connections to the diode board, alternator, points, and starter motor when I replaced the timing chain; The second write-up shows the details about the circuit board connection areas inside the headlight shell and how to connect the right handlebar switch inside the headlight shell.

I hope these write-ups will be helpful when you are installing these components and/or putting a wiring harness back into your bike.

1975 BMW R75/6: Replacing Left Side Handlebar Switch

I had to replace this switch and decided to document “what wire goes where” inside the headlight shell on the circuit board and to the ignition switch and headlight relay.
I also explain how to map information found in various wiring diagrams to the labeled areas on the circuit board. There are some places where things got confusing for me in going between the various published wiring diagram(s) and the circuit board inside the headlight shell, so I hope this material helps others avoid being confused.
You will find this write-up here:

Here are a couple pictures from the write-up.

Broken Left Side Headlight Switch

Broken Left Side Headlight Switch

New Switch Assembly with (8) Wires

New Switch Assembly with (8) Wires

Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]

Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]

Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board

Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board

1975 BMW R75/6: Rebuilding Master Cylinder & Caliper

This bike uses a single ATE 38 mm caliper (as in the size of the piston inside the caliper, not the size of the caliper shell). In 1976 the ATE caliper was changed to a 40 mm model to improve braking. There was also a change to the master cylinder mounting system resulting in a single hole in the brake fluid reservoir that mounts on top of the master cylinder. Other than these small changes, the work I did applies to all the /5, /6 and /7 models of the ATE caliper and under-the-tank master cylinder.

You can read about how to do this work here:

I had occasion to work on both my 1975 R75/6 and someone else’s¬†1976 R75/6 at the same time, so there are some pictures of the markings on the 40 mm¬†caliper and the different mounting systems (two hole and one hole) of the¬†brake fluid reservoir.

Some pictures from this write-up are below.

Master Cylinder & Fluid Reservoir Mount Under Gas Tank

Master Cylinder & Fluid Reservoir Mount Under Gas Tank. Note the Evidence of Brake Fluid Leak.

Earlier Style Master Cylinder Fluid Reservoir-Two Holes With Mounting Bracket

Earlier Style Master Cylinder Fluid Reservoir-Two Holes With Mounting Bracket

Later Style Master Cylinder Reservoir-Single Hole With Threaded Sleeve

Later Style Master Cylinder Reservoir-Single Hole With Threaded Sleeve

Earler Two Hole Master Cylinder

Earler Two Hole Master Cylinder

Master Cylinder Piston Assembly Removed

Master Cylinder Piston Assembly Removed

Removing Top Hat From Master Cylinder Piston

Removing Top Hat From Master Cylinder Piston

Master Cylinder Rebuild Kit Parts

Master Cylinder Rebuild Kit Parts

New Master Cylinder Piston with New Rubber Seals Installed

New Master Cylinder Piston with New Rubber Seals Installed

Master Cylinder Installed on Frame Tube

Master Cylinder Installed on Frame Tube

R75/6 Caliper Seal Kit - Source: MAX BMW

R75/6 Caliper Seal Kit – Source: MAX BMW

Caliper Showing Piston and Dust Seal

Front Face of Piston with Center Hole Surrounded by Rubber Dust Seal

A Blast of Compressed Air Removes Piston

A Blast of Compressed Air Removes Piston

Dust Seal Installed in Large Groove in Piston

Dust Seal Installed in Large Groove in Piston

Pulling O-ring On Eccentric Pin With Pick

Pulling O-ring On Eccentric Pin With Pick

Movable Pad with Flat Face of Pad Pointing to the Front

Movable Pad with Flat Face of Pad Pointing to the Front

Fixed Pad Secure with Wire Clip

Fixed Pad Secure with Wire Clip

Caliper With Painted Metal Line Installed

Caliper With Painted Metal Line Installed