Transmission noises

[hmmmya]

Hope u can help. I want to gauge what is likely wrong before strip the bike down.
BMW k100 1986 engine but whole bike is a bitzer. I've owned for 6yrs and put on 45k  on her and totalling 85k now.

Gear box ran very low on oil due to leak out the clutch boot. Leak isn't a split boot but corrosion on the alum sealing surface.

Now I noticed this due to removing my ear plugs one day, I've been doing lots of commuting and have rarely ridden with out plugs lately. Anyway I noticed a slight dragging transmission noise on accelerating and engine braking. So slight it could be missed if you didn't know the bike. Pull the clutch in it goes away. I've drained the remaining oil with no visible metal in the pan. Refilled to spec and still hear the noise. Is it gubbed? The gears work fine and clutch operates as it should. Any ideas? I was going to strip it down and do a full spline lube anyway but would quite like to know what I might be in for.

Worth noting when I pull the clutch boot off the oil pours out rather than leaks.from memory I think this is wrong but not sure.

Rear drive is fine, I did spline lube about 3yrs back and 20k ago.

Any comments and thoughts would be appreciated.

Thanks in advance.
Duncan (Glasgow ,Scotland)

[johnny]

greetings...

if it was mine... after i fixt that leak...id keep all the fluids proper... getts some moly for gear oils in the transmission oil... ride it often... and wear ear plugs...

j o

[hmmmya]

Thanks Jo, I'll look into moly for gear oil, I've heard it talked about but never seen it sold or looked for it before. I generally have a fast motorway commute to work so will likely strip back and grease everything anyway just for peace of mind. Is it normal for oil to piss out the clutch boot? I'm suspicious it literally Pours out. I changed the clutch lever bearings down there last year and was pretty sure oil barely came out when I removed the boot. Where now oil pisses out if the boot is removed. Comments welcome. Cheers

[Laitch]

Is it normal for oil to piss out the clutch boot? I'm suspicious it literally Pours out. I changed the clutch lever bearings down there last year and was pretty sure oil barely came out when I removed the boot. Where now oil pisses out if the boot is removed.

It is not normal for oil to pour from the boot unless the boot is ripped, the gear case overfilled, or too much free play has been allowed at the clutch lever. A small amount might leak when the boot is removed. How much oil have you put in there and how did you measure it? How much free play is at the clutch lever? Here's a little reading.

[hmmmya]

Thanks I'll investigate further then, gear box was filled using circa 750mm then checked height with BMW tool so oil was too the line, the adjustment feels nice and doesn't seem excessive. I measured and adjusted it last year and haven't noticed a significant change but will recheck. Thanks for the info. The leak was actually coming from the larger diameter sealing surface directly on the gearbox so not affected by the spring. Will let u know what unravels.cheers