Tag Archives: R100s

Disassembly of an airhead R75/5 BMW final drive

Posted on by

Here is a photo essay of sorts detailing the disassembly of a 1973 BMW Final drive. The same applies to all 1970’s era BMW’s (R90 R100 R75 R80 /5 /6 /7 S etc). The seals were shot inside causing leaks. The splines are decent so no need to weld on a new set of splines. I plan to have the drive blasted and powder coated to match the rest of the bike for an upcoming build.

The image descriptions have notes on the disassembly.

  • Final Drive missing a spring
  • Final Drive brake shoes removed
  • The next step is holding the drive gear in place, flattening this washer down, and removing this nut with a good impact gun.
  • Nut off
  • Gear removed
  • BMW tool used to remove the threaded ring inside this shaft area
  • Threaded Ring removed with seal inside.
  • Seal Removal 28x55x9 Part number 33 12 1 231 542
  • Note the orientation of the shoulder of this washer
  • Notice the orientation of the shoulder on the washer
  • removing that large washer
  • Removal of the M8 nuts with a 13mm socket
  • Removal of the M8 nuts with a 13mm socket
  • I’m pretty sure this was a M5 screw I had lying around. Ignore the red locktite looking stuff at the tip. These screws are needed to push the cover off the housing.
  • Two halves apart
  • Notice the shim/washer. Also take note of that small pin in the casting just above the gear. That pin needs to be removed to remove the needle bearing nested inside the housing.
  • There is that same shim from the last photo
  • Press out the axle bushing/tube
  • bushing comes out this side
  • Differential gear is next
  • Press out the differential / crown gear
  • Notice the giant shim/washer
  • Press out the seal from the cover plate.
  • Press out the seal from the cover plate. 65X85X10 part number 33 12 1 233 528
  • spring side goes towards the oil.
  • This housing was put in the oven at 350 degrees for about 20 minutes
  • Removed gear and bearings – HOT TO TOUCH!!! They practically fell out of the housing
  • Unfortunately this pin broke preventing me from removing the bearing. It is common from what I understand. I ended up covering it up with silicone to prevent media from getting at it when blasting.
  • Final Drive Disassembly Gallery
    Seal Removed – 30x42x7 part number 33 12 3 004 337

1978 BMW R100S Restoration

Posted on by

A 1978 BMW R100s fixed up and released back into the wild.

This bike is an absolute dream to ride. It runs amazingly smooth.

I had to go through some serious DMV hoops to get the salvaged title status back on the road with a deadline of 5 months until I incurred DMV penalty fees.  I made it to the registration day with 2 days to spare.

I cleaned, restored, replaced, rebuilt whatever it needed to get it back on the road.  The front end is from a spare R90/6 that I had lying around.

 

1978 BMW R100S with R90/6 front end. by Josh Withers
1978 BMW R100S with R90/6 front end. by Josh Withers
1978 BMW R100S with Oshmo emblem by Josh Withers
1978 BMW R100S with R90/6 front end. by Josh Withers
R100S Straightened in frame jig
Powder Coat
Steering Race installed
Steering Bearings
Steering Bearings
Assembled front end
Forks Rebuild with new fork seals and all the goodies
Reinforced rear frame tab for passenger pegs and muffler hangers
Powder Coated and Reinforced rear frame tab for passenger pegs and muffler hangers
Swing Arm Bearings installed
1978 BMW R100S with R90/6 front end. by Josh Withers

Reinforced Passenger Peg Muffler Hanger tab on BMW motorcycle

Posted on by

This is one of those things I try to do to every BMW motorcycle I rebuild.

The Motorcycles Cushman Truckster is one of the more popular models of bikes in the United States. It has been around since the mid nineteen-hundreds and has always been a top seller among collectors and bike lovers. While it doesn’t come with a warranty, you can get around that by getting a Cushman Tribute package, which pays for repairs or parts that might need them in the future. There are many sources online for Cushman bikes, including parts selection, prices, and even complete restoration packages for your bike if you’re not sure what you want to do with it. When you buy this bike, be prepared to spend a little extra money up front to purchase the bike you want. But remember, it will end up being cheaper in the long run because of the extra care you’ll be taking with it.

It is almost never the engines in BMW`s that are the problem; properly serviced with clean oil at regular intervals, and no abusive riding, they should easily see 200,000 miles

This area is cracked on nearly every frame I tear down. It is the rear foot brake area which also is the muffler / silencer hanger, and where the passenger foot pegs attach. This frame is a 1978 BMW R100s. If you are considering rear sets on your bike that attach to this section, then I HIGHLY RECOMMEND doing this procedure.

cracked tab near rear foot brake pivot hole on BMW airhead framecracked tab near rear foot brake pivot hole

cracked tab near rear foot brake pivot hole on BMW airhead frame

New piece of metal to weld onto the old cracked section to reinforce the area making it MUCH stronger and no longer prone to cracking.

Welded metal onto the rear foot brake section of a BMW R100S

Finished powder coated frame with the welded metal. This area is out of sight to most people unless they take the rear tire off.

Final drive spline rehab

Posted on by

I can’t remember the condition of this final drive when I assembled my 77 R100s back in 2003.  When I had my rear tire replaced recently, I noticed how terrible the splines are. The splines on the wheel are better then the final drive but they will need replacing someday too.

I found this drive with the same ratio and cleaned it up and replaced the spline.  Now it is time to swap the drives.

While it is apart, I am taking the opportunity to pull the tranny back and lube the clutch splines as well.

Bmw final drive spline

Bmw R100S final drive spline replacement

Check out Oshmo.com

Posted on by

Just an update… I have 3 bikes in the works but they have been taking longer then expected.  I’m trying to customize many features vs buying the available parts out there.
And, I’ve been busy over at Oshmo.com helping to develop some Airhead aftermarket parts that look good, and function, for customizing these old BMW’s.

Recent additions are rear sets, and top clamps…  more ideas to come!!

Black Rear Sets for 1970's BMW motorcycles

Black Rear Sets for 1970’s BMW motorcycles

 

 

Ed Korn Cycle Works Swingarm seal removal tool

Posted on by

Removing these seals is a frustrating process.  Prying them out usually doesn’t get you anywhere.

I bought Ed Korn’s tool a while back and it can be used for pulling both the races, and the seals.

Here is how you use it to pull the seals.

Here is the tool assembled

photo-1

 

I first cut out some of the seal’s rubber with a razor blade.
It was easier to get the tool installed that way.

 

photo-2

photo-3

Then you tighten the threaded rod with the allen fitting at the end of it.  By doing so, it expands the nut against the screws and presses them outward so they ‘catch’ under the metal part of the seal.

photo-4
Then you install the collar, plate and washer and nut.

photo-5

Once you begin tightening that nut, it will pull the seal out into the collar.
image_1
You can then loosen the nut, and break the old seal free with a few taps with a hammer.


image_2

 

 

Cad Plating

Posted on by

A friend turned me onto the idea of having those old, nasty nuts and bolts cad plated.
After disassembling 4 BMW motorcycles over the years, i developed a few ziplock bags of rusted, filthy, oxidized junk.

After i gathered everything up in a tupperware container, it weighed close to 50 lbs.

I should have had this done before my latest restoration but nothing will beat the stainless steel hardware I have used throughout the bike.

This will, however, save me lots of money and trips to the hardware store.

It was a heavy load for one saddle bag. My bike was all over the road having ‘dead weight’ on one side of the bike.
Bikeimage_1C

These were pretty much un-usable parts. I threw in some fork plates, rusted axles, and other bits just to see what would happen. Whatever was aluminum couldn’t be plated but they got blasted clean anyway.
Dirtyimage_2C

A day later and $80 out of my pocket and into the pocket of the guy who did this ‘under the table’ and this is what I got.
CleanimageC
Cleanimage_3C

I spent about 3 hours watching TV, drinking beer and organizing everything. I would have been watching TV and drinking beer anyway…
And at anywhere from $.07 – $.60 per washer, bolt, nut and screw from the hardware store or from BMW (some parts are $2 or more), I think just the contents of this container is worth it.
WashersphotoC