Clutch/ gearbox rattle

[Pattern14]

Just thought i would ask the question that has no doubt been asked before. 1978 R100S, 1/2 a million K's on the clock plus, and the rattle sounds to come from the clutch area. Quiet when cold, clacking noise when hot, still present when you pull the clutch in, but not as bad. I've lubed the spine and pushrod assembly, which helps a bit, but no cure as such . Everything works fine though, apart from the annoying noise. There is no felt around the pushrod, and I was wondering if wear on the clutch pushrod components could be the culprit. The bike has big miles on it, so any thoughts appreciated.

[khittner1]

I don't know the source of your rattle, Pattern, but I do love seeing questions about weird noises on an airhead with 300K-500K miles on it! I hope I'm still able to generate some weird noises when my airhead gets to 500K . . .

[Pattern14]

All going well, your bike will still be running too I realise that at the this end of the mileage spectrum you expect wear and tear, but experienced boxer mechanics are practically non existant where i live, and no-one I know has a bike with really big miles on it. I usually do my own work anyway, but sometimes things just baffle me.

[Kurt in S.A.]

What sort of replacement/maintenance history is there on the clutch and gearbox? If it's all original, I would imagine that a whole lot of play is showing up, especially the spline coupling, maybe even the gears in the box. Usually when you pull the clutch lever in, that quiets things down a lot. If it's still too loud for comfort, could there be slop between the clutch disk and the input shaft splines?

Kurt in S.A.

[Dave Backmarker]

Pattern,
Can you describe the clacking a bit more? I assume it's not a metal on metal scraping sound? More of a rattling?

The lack of felt on the push rod will allow it to rattle but I'd expect it to quiet down a lot when you pull in the clutch. How old is the clutch disc or diaphragm spring? I'm wondering if rivets on the clutch or spring are coming lose.

Dave
1975 R90S
2000 R1100RT

[Duane Ausherman]

You can test to see if the rattle is in the box or clutch. Get the idle down to as low of RPM as possible. That makes the rattle sound worse. This lets you know if it gets better or worse.

Put the transmission in gear and pull in the clutch. In that condition nothing is moving in the transmission, so any rattle is in the clutch splines.

Being quiet when it is cold is great indicator that the rattle is in the box. When the oil warms up, it allows more rattle than when cold.

When hot, do you have any sign of grabby clutch? The clutch should be equally easy to smoothly engage when hot or cold.

Way too much is blamed on spline lube, or the lack thereof.