17 January 2004 - Today I started to prepare the wheels for disassembly. The photo below shows the rear wheel. The hubs are the same on both wheels however there are slight differences with the rims and spokes.

The rear wheel has no dimples in the rim. The spokes have shoulders on both ends (larger diameter than the center diameter). The spoke diameter in the center is 0.16" (4mm) and the spoke wrench needed is 0.27" (7mm).

The front wheel has 5 dimples in the rim opposite the valve stem. The spokes do not have shoulders on both ends. The spoke diameter in the center is 0.14" (3.5mm) and the spoke wrench needed is 0.24" (6.1mm). The area that is circled in red is one of the dimples (it may be hard to see).

I was not able to get a spoke set for an R12. Vech sent me a stainless steel spoke set for an R51/3 half hub that he thinks will work. The photo below shows one of the spokes. It is a shouldered spoke. The center diameter of the spoke is 0.155" (~4mm), and the spoke wrench is 0.235" (6mm). If the spoke nipples will work for both rims I will use them (I know they will work for the front). I will sandblast them so the paint will adhere right.

The photo below shows the hub nut off of the front wheel. The pin diameter to remove this is smaller than the /2 and the /3. However the pin diameter for the rear nut was the same as a /2 (4mm). I am going to drill the pinholes out on this nut to 4mm (I had to remove it with a punch and hammer, I have a tool for 4mm pins).

This is a photo of the bearing spacer that is right below the nut.

Here is the open wheel bearing (2 per hub). I will be replacing this with a sealed bearing (I think 6304), which will not require any greasing. I will retain the outer nut and felt oil seal for cosmetics.

I have ordered a couple of tire irons and a spoke wrench. Once I get the tire removed. I will measure the location of the hub relative to the rim with a device I will make out of a couple of pieces of sheet metal and some screws. This will give me the data I need to reassemble the wheel.

19 January 2004 - I made a tool to measure the offset distance between the hub and the wheel so I could get some measurements prior to teardown. Once the measuring bolts are set at a reference point, this tool can also be rotated around to check if the offset is uniform around the wheel. I was hoping this would be the case on my wheels…no luck. Both my wheels have offset variation as you rotate the tool around the wheel and the offset distance is different for both. The only thing they have in common is that the hub is higher than the rim on both wheels. The offset was measured on two sides. The offset on one of the wheels was 7.62mm and 6.858mm, the other wheel was 10.41mm and 10.9mm. So what is the correct offset? I am trying to find out. I believe is should be the same for both wheels as they are supposed to be interchangeable. The photo below shows the tool I used and the measuring points.

27 January 2004 - I contacted the BMW Historical Archives in Germany to see how much higher the hub should be relative to the rim. They found an original dimensioned wheel drawing and the distance is 7mm. Tonight I disassembled the rear wheel. Some of the spokes came loose. Others were rusted solid and had to be cut off.

Here are the spokes and nipples from the rear wheel compared with the R51/3 stainless spokes. The length and heads that hook into the rim are the same. The diameters are slightly smaller and the nipples are smaller. I have fitted the nipples in the rim and I think they will work (nipple hole in rim 8.56mm, nipple diameter is 1mm less). The spokes and nipples should be a much better match to the front wheels (which is definitely correct for the bike).

28 January 2004 - Tonight I dismantled the front wheel. Below is a photo of the rim

Here is a comparison of the spokes on the front wheel. Close match. The nipple is a little bit longer but a nice fit to the nipple hole (~7.4mm).

30 January 2004 - Today I removed the bearings out of the hubs. The photo below shows the inside of the wheel hub where the bearings and spacers go.

The photo below shows the bearing and spacer stack. Notice the spacer on the left, I pretty much destroyed it when I was pressing the bearings out on the first wheel. On the second wheel I press the stack down until I could reach my finger down inside the hub and flip this spacer up on its side allowing the press to contact the bearing directly. The good news was that I have a postwar spacer that is identical to replace it with. The bearings are 6304. I am going to replace them with sealed 6304 bearings to eliminate the need to grease the hubs.

Feburary 1 2004 - Today I sandblasted the wheel hubs. They are in pretty good condition overall.

The five dimple rim had some text stamped on the top of the rim. It appears to be "Kronprinz = Licherheitsfelge" but is hard to read (I found out this roughly translates into "safety rim"). The other rim had a couple of barely legible numbers stamped in it. 2061(?) 1 64 240 0 and 3x? 19 1 41 B. These may be BMW part numbers and date codes.

February 14 2004 - Today I sandblasted the hubs and some other small pieces.

Inside the hub was the number "1661" stamped (both hubs). As I was removing the paint the original coat of gray was under the black over paint.

March 22 2004 - Today I picked up the primered hubs and rims. Next is new bearing installation and wheel lacing. Then they go back for painting.

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