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It's time to install the clutch. The following text and drawing was taken from the BMW R51/2 Owner's Manual: The engine power is transmitted to the transmission by means of the single-disc dry clutch with the flywheel mounted on the conical journal of the crankshaft by a key and screw driven into the plate. The BMW R51/2 handlebar clutch lever is on the left. Power transmission between the engine and gearing is interrupted when the clutch lever is operated whereby the pressure plate is lifted from the driven disc by means of push rods. The robust single-disc dry clutch needs no maintenance. |
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Remember I said I had two R51/2 engines? Well, how would you like the job of sorting which springs are clutch springs and which springs are valve springs? Vech showed me where the clutch springs are slightly larger at one end, while valve springs are the same diameter at both ends. |
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To assemble the clutch, place the clutch springs in the hole of the flywheel with the larger end toward the flywheel. Lay the back of the spring plate over the springs with the springs centered in the circular indentations in the back of the spring plate. The six holes of the spring plate must be in line with the six posts on the flywheel. |
 | Lay the clutch plate on the spring plate. Add the thrust ring and insert the clutch line-up tool through the center of the clutch plate to center the clutch in the flywheel. Thread three clutch compression tools in every other hole of the spring plate. Tighten all three of the wing nuts of the compression tools in a even, progressive manner until the entire clutch assembly is drawn tight; compressing the clutch springs, spring plate, clutch plate and thrust plate as a unit into the flywheel. |  |
 | Sparks fly when Vech and I work in the shop together. Yes, I'm kidding. The truth is, we had no clutch screws, so Vech tried a clutch screw intended for BMW R50 models. The thread was correct, but it was too long. Vech used a hack saw to cut about 10mm off one bolt. Clutch bolts are hardened steel which means they are pretty darned hard to cut. I suggested that he try my trusty Dremel tool and it actually worked better. After Vech cut all six clutch screws, we inserted three of them (while the three clutch compression tools were still in place). Vech set those three clutch screws with a hand impact driver. He then removed the three clutch compression tools, inserted three more clutch screws and tightened them with a hand impact driver as well. |
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Halloween,
2001 was an exciting time for Vech and me. (No, we didn't go
trick-or-treating.) It was time to put the engine into the frame! We
selected a stainless steel engine mount bolt for the rear and a
stainless steel, sidecar-ball engine mount for the front. We used a
sidecar ball because I plan to try the R51/2 with a sidecar. I have
zero sidecar driving experience, so it will be definitely a trial thing
as far as I'm concerned. The photo shows how Vech ran the engine mounts barely inside the frame and let them hang there. He positioned a jack to hold the engine so we could manipulate the engine and get the engine mounts to go through it. It is a combination of talents that makes a success of this job: standing on the work table, balancing, pushing, cursing, adjusting the jack and whacking the end of the engine mounts with a rubber mallet. To add to the excitement, the engine mounts must also pass between two engine spacers (inserted on the left side of the engine, against the frame). After the engine mounts were pounded home, Vech and I stood back and admired our progress. Vech said "if we only had (this)" and "if we only had (that)"...and this...and that...and... I thought "Yes, if only......all that and my R51/2 would be ready to ride. As things were, we called it a night. I wondered what normal people think about on Halloween night as they fall asleep. I thought about motorcycles ;-) |
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