mcman56 Posted July 23, 2011 Report Share Posted July 23, 2011 My c15 slips out of 1st under a light load. So far at least, it has not done this under hard throttle. There are no sounds or jumps, it just sort of slips into neutral. I pulled it apart and the cam plate had a little defect where it catches the spring in first gear so I cleaned it up square with a carbide end mill. It seemed OK but after getting hot it started slipping out again. The cam plate has no BSA or part number markings. I have ordered a new one. The bike was dead when I got it and so I did a total disassembly with replacement of any suspect parts. If it was anything obvious I probably would have seen it. It does not slip out of other gears or have any other shifting issues. Quote Link to comment Share on other sites More sharing options...
copemech Posted July 24, 2011 Report Share Posted July 24, 2011 Jeez man you are hard core to get into that! Unfortunatly it does rather sound as if the actual engagement lugs on the gears sides are worn where they slide together and cam out under light load. Not that I know beans about that animal! Quote Link to comment Share on other sites More sharing options...
jack_the_lad Posted July 25, 2011 Report Share Posted July 25, 2011 My c15 slips out of 1st under a light load. So far at least, it has not done this under hard throttle. There are no sounds or jumps, it just sort of slips into neutral. I pulled it apart and the cam plate had a little defect where it catches the spring in first gear so I cleaned it up square with a carbide end mill. It seemed OK but after getting hot it started slipping out again. The cam plate has no BSA or part number markings. I have ordered a new one. The bike was dead when I got it and so I did a total disassembly with replacement of any suspect parts. If it was anything obvious I probably would have seen it. It does not slip out of other gears or have any other shifting issues. Back in 1972 I ran a C15 on the road (I still have the bike) I had the same problem. When I went to the local BSA dealer he said change the lay shaft bush, I did and it stopped jumping out of 1st gear. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted July 25, 2011 Author Report Share Posted July 25, 2011 Back in 1972 I ran a C15 on the road (I still have the bike) I had the same problem. When I went to the local BSA dealer he said change the lay shaft bush, I did and it stopped jumping out of 1st gear. Would this be the bush in the main engine cases? Mine is the early style transmission,1960. The later ones seem to have more options for shimming. One odd thing about this transmission is that it has the wide ratio first gear and close ratio gears 3 through 4th. Quote Link to comment Share on other sites More sharing options...
b40rt Posted July 25, 2011 Report Share Posted July 25, 2011 Had a similar problem on my B40, adjusted the pawls on the plunger quadrant, been fine ever since. (20 years) Quote Link to comment Share on other sites More sharing options...
mcman56 Posted July 27, 2011 Author Report Share Posted July 27, 2011 Had a similar problem on my B40, adjusted the pawls on the plunger quadrant, been fine ever since. (20 years) How do you adjust the pawls? I don't see anything to adjust? Quote Link to comment Share on other sites More sharing options...
b40rt Posted July 28, 2011 Report Share Posted July 28, 2011 How do you adjust the pawls? I don't see anything to adjust? Small screw from memory. Took off the second casing and put it in a vice (carefully) put shaft and quadrant in and adjusted. Locktited screws. If you have a new quadrant, these have variable quality. Have you got Rupert Ratio book ? ISBN 0-9535098-1-8 Quote Link to comment Share on other sites More sharing options...
mcman56 Posted July 28, 2011 Author Report Share Posted July 28, 2011 Small screw from memory. Took off the second casing and put it in a vice (carefully) put shaft and quadrant in and adjusted. Locktited screws. If you have a new quadrant, these have variable quality. Have you got Rupert Ratio book ? ISBN 0-9535098-1-8 I have the book but I can't find anything on adjusting the quadrant. I pulled the quadrant out but still do not see what to adjust. The two plungers look to be located in holes with no adjustment potential. The plate with the screw just seems to hold them in place. One interesting thing is that on one side, opposite the plunger, the flat surface is built up with about 1/16" of what looks like brazing. This area contacts the built up flats in the engine cases to limit the shifter travel. It is on the side that would limit travel on up shifts and I can't imagine why someone would do that. Thanks for your help with this. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted July 30, 2011 Author Report Share Posted July 30, 2011 I put in new cam plate. It looked a little different from the original, like it may engage further. It also had a newer part number than the original parts list. This is a distributor model. I did not see why it would make a difference but swapped the shift forks at the same time. The shifter now feels different when shifting, like more is going on. It worked OK during an hour ride so hopefully it is cured. Quote Link to comment Share on other sites More sharing options...
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