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Various parts of the wheels on the R51/2 are different from later plunger bikes. My wheels were in pretty good shape so I was able to reuse the rims and hubs. The spokes, wheel bearings and hub nuts were replaced. The spokes on plunger frame twins come in three sizes: M3.5, M4 and M5. The R51/2 wheels use the smallest of these three spokes. You can see from the picture that the spokes look delicate, even without a comparison to the larger spokes. Vech did not have the small spokes, and Mark Huggett was out of stock at the time I rebuilt my wheels. Motorrad-Stemler and Uli’s Motorradladen did not have the smaller spokes either. I called Kenny Buchanan at Buchanan’s Spoke and Rim. Kenny fixed me up with the closest match he could – spokes intended for British bikes – and they fit close enough to use, but the shape of the nipple where it seats in the rim was less than perfect. I have since gotten correct spokes from Huggett, and will likely rebuild the wheels sometime in the future. I had the steel wheels cleaned up and reused them partly because reproductions were not available with the smaller nipple holes required for the R51/2. Reproduction wheels are now available from Mobile Traditions. |
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| You can see from this ‘after’ picture a couple of differences between the R51/ and R51/3. First is the lack of the iron band around the half-hub on the R51/2. The other difference is the presence of a grease fitting in the middle of the hub on the R51/2. The theory behind the grease fitting is that it would make it easy to periodically service the bearings without removal of the bearing stack from the hub. In fact I bet this turned out to be a very efficient way to grease the front brake shoes if you did not bother to remove the wheel before putting grease through the fitting as directed in the owner’s manual (what owner’s manual?) so that you could clean off the extra grease as it moves past the inner bearing. |