Hello all
I am currently recommissioning an early 1946 B31 which has lain dormant for the last 20 years in the previous owner's shed. All nearly complete now, except that I cannot stop the clutch from dragging. it is so bad that I cannot select any gears with the engine running. The clutch is a 6 spring type with 3 drive plates.
All the plates are straight with no apparent damage. I have been very careful to ensure that the 6 springs are tensioned correctly so that when the plates move in and out, they remain level all the way round. The clutch push rod and cable adjustments are correct. The primary chain also has the correct amount of slack at its tightest point.
With the primary chain case cover removed, I can see that the outer plate moves out about half and inch when the clutch lever is pulled in, and with the lever fully in, the outer plate is almost flush with the rim of the clutch housing. All the clutch plates slide freely within the clutch housing.
So why does the clutch drag? I have got to the point where I think it is worth removing one of the plates, to see if that works. However, that might then allow the clutch to start slipping?
Has anyone got any suggestions?
Many thanks
Bob
sounds like alignment, with the lever pulled in kick it over and see if the outer plate spins free, id not align be adjusting springs
If you put the bike into a gear when stationary with the engine off, can you pull the clutch lever in and kick it over or is the drag so bad you cannot easily depress the kick start?
I know on my bikes, if they have been standing a while the gears go into first with a BIG clunk when first started as the plates obviously are "sticking " together a bit. This happens on new and old bikes.
Remember they were not that good even when leaving the factory. I try to remember to free the clutch before starting the bike ie. kick it over with the cluctch pulled in.
When selecting 1st from stationary rock the bike back and forth as you select gear and don't rev too high.
Its interesting to note that the army riders instructions for selecting gear in the M20 are far more extensive than the simple BSA instructions!
Thanks all
The outer plate does spin with the lever pulled in and when kicked over. Is that correct?
I don't think it is a case of a sticking clutch because I have stripped it down, and am watching it operate without the chainscase on.....
The gears were difficult to engage when I first got the bike, especially first, but at least they did work. So I have to hold my hand up and admit that it must be something I have done...... I initially stripped the clutch in order to just remove the back plate of the chaincase, as the gaskets were all leaking, so perhaps there is a problem with the way I have refitted the clutch housing and bearing itself? I don't reall think so, because the primary chains runs straight.
I guess I will have to undo the whole lot again and see if anything looks wrong.
The six spring clutch is no not the best of clutches, but having said that, I bet if you examine the slots in both the chainwheel and centre hub, they WILL BE WORN. This is indicated by the slots having depressions where the tang of the plates make contact. Being rippled like that make TRUE disengagement when the engine is running difficult as they are pushed together holding plate in notch, but appears to look ok operated when not. Strip the clutch off the machine and spend plenty of time carefully filing the slots as flat as you can get. To do this properly will take a vice and a fair amount of time (hours rather than minutes) and a good 1/4 inch square file, that has been broken off at the point the file stars to curve into towards the end (you want as straight a slot as you can get). Dress any burrs off the plate tangs with the same file. Do this and adjust the clutch correctly and I guarantee it will work fine. Alternatively buy new hub and chainwheel - expensive. Ps wash any oil off the plates with petrol before assembly.
Many thanks Malcolm - it looks like you are right! Having looked closely, there are indeed indents on the drive plate tangs, so I'll strip it all down again and do as you recommend, and hopefully, that will finally sort it.
Thanks again!