gear lever lengths

I have been having great difficulty changing gear on my recently purchased Commando, it has one of the 45 degree cranked levers with a rearset footpegs and I thought it may have something to do with the angle causing sideways forces. I decided to try out a standard lever in a reversed position like I used to have on an 'S' many years ago so I borrowed a lever from a mates Atlas and it seemed to be too long (about 150mm from centre of shaft to centre of rubber )it is too close to the footpeg and also fouls the kickstarter, some levers available on ebay quote lengths of 127mm from centre to centre and the Andover Norton site has a picture comparing their 'original' which is shorter than 'pirate' copies but the long one I borrowed is definitely original since he's owned the bike from new. Were the Commando and Atlas different lengths? Also can anyone suggest other possible reasons for not being able to change gear when moving (stationary it will click through the gears when moving the lever by hand)? There is some slop in the bush between the shaft and outer cover, I have washed and replaced the clutch plates and the clutch nut seems to be tight.

Its common for the primary chain to get too tight once road heated and hang up shifts, usually 1st N 2nd so check that 1st thing. The lever should not need much force so doubt the angle on shaft matters much, just toe access distance. Pawl spring is another infamous reason for missing shifts but wouldn't think moving or still would change its shifting faults. I've had bushes especially the paper thin 1st cog one break up so shifting whille rolling was iffy and wouldn't stay engaged in 1st when loads matched at slow coating speeds and engine drag, suddenly in Neutral freedom. At rest it shifted ok maybe because no wobbling as when rolling. I've had the dog faces smear off d/t worn bushes tipping cogs and that made shifting difficult. May just be oil fouled clutch plates. I've used rear set with flipped over lever and worked a treat but didn't like the pattern so put on the over head linkage to suit my reflexes and toe clearance laying over. Likely time to learn more about old worn Norton drive trains the good ole hard way and let us know what ya found that fixed it.

what Hobot said...

lever length is more a function of footpeg placement than the actual leverage needed to shift. If you can't shift easily, most likely culprit is a too tight primary chain, especially if it seems to shift OK when stationary. If you had set the proper slack on the primary chain, one cause could be a too loose top bolt on the transmission. As you accelerate, the final drive sprocket pulls on the chain, which pulls on the rear sprocket, turning the wheel. The force pulling the rear wheel forward is also trying to pull the transmission backward, and if that top bolt isn't properly torqued, it will slip, tightening the primary chain and possibly twisting the transmission in the cradle. If the adjuster is tight, the transmission may slip back in place when stopped, and you'll be left scratching your head. It doesn't take much movement of the clutch drum to make the primary chain taught, so if this is what's happening, you may not even see a telltale rubbing on the cradle slot.

I had a situation on my P11 (the top mount is a special thin head bolt) where the head actually separated from the bolt and got a similar result. I replaced the bolt with a stud, and could just fit a standard nut if I used a thin washer.

edward said:

some levers available on ebay quote lengths of 127mm from centre to centre and the Andover Norton site has a picture comparing their 'original' which is shorter than 'pirate' copies but the long one I borrowed is definitely original since he's owned the bike from new. Were the Commando and Atlas different lengths?

Click to expand...

The 850 Mk3 lever is shorter (about 110mm C to C).

Are you using a parallelogram gear shift arrangement with your rear sets or a reversed lever ? A reversed lever can bring the situation where your foot is putting part of the force up the lever rather than into a rotary motion.

The bike is a Dreer Commando with belt drive, I have just checked the gearbox mounting bolt and its tight, as already mentioned I've cleaned all the clutch plates. It has the reversed 45 degree cranked lever and that's why I was thinking this combined with the endthrust which is inevitable due to the position of the lever might be the reason for my problem. If the Mk111 lever is 110mm centre to centre then that means there must be at least 3 different lengths of lever available! I think all I can do is get one of the shorter levers and try it and if it doesn't help I'll have to strip the gearbox and clutch just to check everything. The bike was 'remanufactured' in this manner so it must have worked then. I liked the clip of the 880,they sound even better in the flesh if only I could get it out of first gear...