Friday, April 7, 2017

The Sin of Omission… 1964 CA77 clutch mystery-solved!

My friend, Javier, has a bright red CA77 Dream which he’s used sparingly for the past 6+ years. He called the other day to ask me to help him solve a shifting problem that he had suddenly encountered. Despite monthly rides to keep the bike in operating condition, suddenly the clutch wouldn’t disengage when he tried to ride it last week.

All the symptoms sounded like a “stuck clutch” syndrome, which often happens when the bikes are laid up for many years. It didn’t make much sense that the clutch would suddenly act up like that after regular use, so the only thing to do was to have him bring it over for a look. After checking the clutch cable and clutch adjuster for proper settings, the bike continued to lurch into gear and die when any attempt to drive it began. I suggested that he ride it down the driveway in neutral, pull in the clutch and drop it into gear; then continue to ride the bike up and down the street in gear with the clutch lever pulled in to see if it would break loose. He had no luck doing that, so was obviously time for a clutch inspection!

The bike is mostly stock except for front crash bars, rear grab rail and some re-purposed HD mufflers installed on the stock header pipes. The oil was drained and work commenced on disassembling the left side of the bike; exhaust pipe/muffler, footpeg, shift lever, oil filter cover and all the clutch cover case screws (Socket head screws on this machine). The oil came out a little dirty after circulating for the past 5 years, but there were no signs of any large particles in the drain pan and the engine’s left side components were all relatively clean showing that someone had done an overhaul on it during the restoration process.

Once the cover is off, it only takes removal of four bolts to remove the clutch pack from the engine. The clutch pack combo came out like a brick and the remaining clutch plate set, held in with the retainer wires, was stuck together as well. It is hard to imagine that the bike could have been recently driven with a clutch that looked like this. The clutch inner hub was removed and the outer wire carefully taken out of the hub to release the inner clutch plate set. All the clutch plates were pried apart and the steel plates all scrubbed up on a wire wheel. The fiber plates were scrubbed on a Scotchbrite pad, just enough to rough them up a bit. The surfaces were all glazed to some extent, but not from excess slipping or abuse.

With everything cleaned up, the clutch pack was reassembled onto the engine. I fully expected to have a fully functioning clutch now, but after bolting down the outer clutch pressure plate with the four bolts, washers and springs, it was apparent that something was missing! The outer spring-loaded plunger, which is called a “metal oil guide,” was nowhere to be found! It hadn’t fallen out into the drain pan because it was never there in the first place! Whoever had built the engine failed to install the part, which is crucial to supplying oil to the clutch and transmission shafts. The metal oil guide is the bridge between the oil feed hole in the clutch cover and the center of the clutch pressure plate to supply the clutch and transmission with fresh oil. Not only does the oil fail to be delivered to the transmission shafts, the oil which would normally go to the oil filter on the way to the crankshaft bearings is dumped back into the clutch cover, through the existing gap between the cover and the outside of the clutch pressure plate.


I recalled hearing the engine run, years before, there were unusually loud rumbling noises that seemed to sound like bad crankshaft bearings to me. I heard it again when the bike was being run during the attempt to break the clutch loose, prior to teardown. Javier hurriedly fired the bike up and ran it around the block, then shut it down to be loaded back into his truck before I could get a good listen to the engine after the repairs, but I suspect that the crankshaft is going to be a lot happier with a full flow of oil to the bearings from now on. 

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