1973 BMW R75/5 Rebuild: Some Refinishing Information

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I’ve had several questions and Email about how I refinish the rough aluminum casting on the engine, transmission and rear drive and also some questions on how I got the carburetors to look shiny and new again.

NOTE: Refinishing is not rebuilding. Refinishing is restoring the surface of parts to “like new” condition. You are removing crud, stains, grime, dirt, grease, bugs, corrosion, tar, mud and old gasket sealer that have frequently been baked on for 10, 20, 30 or more years. It takes PATIENCE. It is applied Zen Smile

So, I put this together to illustrate some of the techniques I use on this project:

And, some After pics from the write-up:

Polished Hubcaps

Polished Hubcaps

New Rubber, New Spokes & Polished Wheels

New Rubber, New Spokes & Polished Wheels

Polished Engine

Refinished Engine Case and Timing Cover

Refinished Left Side

Refinished Transmission

Cleaned and Polished, Outside View

Cleaned and Polished, Outside View

Powder Coated Right Control Perch with Polished Lever

Powder Coated Right Control Perch with Polished Lever

1973 BMW R75/5 Rebuild: Installing Rear Sub-Frame, Shocks, Key Lock, Seat Latch

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This bit of work finishes up the rear end until I install the fenders and seat. Those will wait for me to strip and paint the body work.

Here is a write-up on this work.

The key lock and seat latch can be confusing to get in, so I took some extra pictures of the assembly process.

Here’s a couple pictures from the write-up.

Rear Frame

Rear Sub-Frame, Upside Down

Marking on Right Shock Pre-Load Adjuster

Marking on Right Shock Pre-Load Adjuster

Securing Shocks by Lower Shackle

Securing Shocks by Lower Shackle

Right Side Sub-Frame Bolts Installed

Right Side Sub-Frame Bolts Installed

Seat Latch and Lock Hardware

Key Lock and Seat Latch Hardware

Attaching Lock Retaining Ring with Screw

Attaching Lock Retaining Ring with Screw

Here is the rear end of the bike when I disassembled it.

Rear End Disassembly

Rear End Disassembly

Supporting the bike before rear end and swing arm removal

Rear End Dissassembly

And how it looks now. Major improvement 🙂

Rear Shocks Installed

Final Product

Lock & Grab Handle

Key Lock and Grab Handle Installed

1973 BMW R75/5 Rebuild: Rear Brake Installation

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Well, I now have the rear brakes installed and am working on getting the rear sub-frame on the bike. When I get that done, I’m going to move on to the front forks and steering.

Here is the write-up on installing the rear brakes, rear brake pedal and mounting the polished rear wheel with the new stainless steel spokes and the powder coated battery box:

Here’s how the bike looks at this point.

Rear Brake Pedal and Wheel Installed

Rear Brake Pedal and Wheel Installed

Final Result

Final Result

1973 BMW R75/5 Rebuild: Install Swing Arm and Rear Drive

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After I got the engine and transmission installed in the frame, it’s time to add the swing arm and the rear drive. Here is the write-up I did for this part of the project.

And, you can find the write-ups for the engine and transmission installation work here:

Here are some of the pictures from the write-up.

Rear of Transmission & Drive Shaft Coupling (Upper Right)

Rear of Transmission with Drive Shaft Coupling (Upper Right) and Frame Protection

Powder Coated Swing Arm with Drive Shaft Inside

Powder Coated Swing Arm with Drive Shaft Inside

Swing Arm Pivot Pins, Lock Nuts and Plastic Caps

Swing Arm Pivot Pins, Lock Nuts and Plastic Caps

Swing Arm Boot - "OB" EN (Top) on Round Section

Swing Arm Boot – “OB” EN (Top) on Round Section

Measuring Swing Arm Gap to Center the Swing Arm

Measuring Swing Arm Gap to Center the Swing Arm

Sitting on Rear Tire to Tighen Drive Shaft Bolts

Sitting on Rear Tire to Tighen Drive Shaft Bolts

Swing Arm and Rear Drive Installed

Swing Arm and Rear Drive Installed

1973 BMW R75/5 Rebuild: Install the Engine and Transmission

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It’s time to put parts back into the frame :-).  The first to go in is the engine followed by the transmission. You can read about what I did here:

I used information from the following resources to plan this work.

As I had the engine stripped down, I was able to lift it into the frame by myself using some straps so my hands weren’t under the oil pan. The transmission isn’t very heavy, but there isn’t much clearance when the engine is installed and I had to remove the kick start lever or it wouldn’t fit.

Here are a couple pictures from the write-ups.

Engine Installation

Polished Engine

Polished Engine Ready to Install Into The Frame

Engine In Frame Resting on Lift

Engine In Frame Resting on Motorcycle Lift

Left Side Shackle and Side Stand

Left Side Shackle Keeps Side Stand on Pivot Pin (Looking Toward Rear)

Engine In Frame & Secured to Lift

Engine In Frame & Secured to Lift

Transmission Installation

Refinished Left Side

Refinished Transmission Ready to Install in the Frame

Clutch Throwout Parts

Clutch Throw Out Assembly Parts

Frame Protection

Frame Protection Before Inserting Transmission In the Frame

Clutch Throwout Rod Bearing Assembly

Clutch Throw Out Bearing Assembly Showing Direction and Order of Insertion into Bearing Housing

Job Done

Transmission Install Job Done