Taking the cover off, I'm finding metal filings in the bottom of the primary chaincase.
I was getting these before I fitted a NOS clutch, I've still got them.
I can't see any obvious damage to components when fitting the new clutch.
The sprockets are in line.
Primary sprocket in OK condition & cush drive spring is tightened.
New Renold primary chain fitted.
I can't detect any play in crankshaft bearing.
The filings seem larger after fitting the new parts, some are about 1mm size.
I was hoping the filings might just be normal wear & tear but have never noticed them like this before.
What do others think?
This sounds rather serious! Could it be that the gearbox shaft is rubbing against the plate that seals off the drive sprocket, behind the clutch? By this I mean the large, adjustable steel item that looks like an eye, and is supposed to keep the oil inside the primary.
I'm assuming the filings are steel. Check with a magnet to see if they're alloy, in which case they have to come from the crankcase.
Look behind the clutch. It may be rubbing on the inner primary cover or felt seal area. Also check the outer primary cover. The metal has to be coming from somewhere.
Thanks for the replies folks. I think I've found the problem.
The locking wire on the 3 bolts behind the engine sprocket had snapped, allowing the wire to abrade against the sprocket. There's no damage to the sprocket or chain that I can see. I suppose the soft wire could be pinched by the sprocket & chain, snapping off small pieces. I'm surprised I didn't notice this when I replaced the chain.
As for the plate behind the clutch that Allan mentions, I don't really understand this. Mine looks in good nick compared with others, it mounts loosely on the inner chaincase with horizontal & vertical movement. I figure the circular opening must contact the rotating clutch to some extent. Does it rely on oil being flung about for lubrication?
My footrest spacer has a few gouges, a chain must've let go a long time ago.
I'm relieved you've found the source of the metal filings. That safety wire is important, so you've just saved yourself from future problems, if the bolts come loose.
As for the plate behind the clutch, my understanding is that it is moveable so that it centers on the gearbox shaft. Once centered it needs to be tightened firmly in place. if it's loose it will start to rub on the shaft and worse.
Ditto...The plate should be able to slide back and forth relatively freely..As the hole in the plate is circular and the back of the clutch sleeve is circular there will only be a 'point contact' anyway and if the plate is free to move there won't be any contact pressure on it either ...Ian
