G: Gearbox (Twin) Output bearing?

[Gary Gittleson]

I posted this on the forum #3 but realized that not everyone looks there. So here it is:

My D Rapide has developed a noise that I think is coming from the gearbox. It's a rather quite whine (or maybe I should call it a hum). The noise is only present when power is applied. Back off the throttle and it stops. It's road-speed related. Changing gears does not change the pitch. Rev up the engine in neutral or with the clutch in and there's no noise. The pitch does seem to go up with speed, but that's hard to discern. I haven't done a high-speed test. The fastest I've run it recently was maybe 55 or 60 mph. But the noise is audible at 30.
So am I right to suspect the output bearing in the gearbox? Winter is coming, so I suppose it'll give me something to do; as if I needed that!

 

[rapide049]

Generator gear to deep in mesh with the primary chain

 

[vibrac]

Bets on Bearing

 

[Simon Dinsdale]

I would go with either a gearbox output bearing or at least something inside the gearbox if its road speed related. I have had a generator gear whine due to wrongly setting up the mesh and that was definately engine RPM related as it was noisy with the bike stationary in neutral and just blipping the throttle.

 

[Gary Gittleson]

It's definitely not the alternator mesh. I had that when I installed the Alton thousands of miles ago. Fixed it then and it never returned. And it is engine RPM related. My bet is on the bearing too. I'll be stripping the gearbox down this winter.

 

[rapide049]

Also check your ESA Springs

 

[Cyborg]

Do you know how many miles it has on it since the gearbox was apart?

 

[Gary Gittleson]

I don't suspect ESA springs but will check. Never had problems with them. It is a D, after all.

The gearbox was apart about 25,000 miles ago.

 

[Cyborg]

The reason I asked…. Many years ago I bought a Rapide that developed a bearing noise, but it was after a lot less than 25k. The previous owner had assembled the gearbox with the G5 (layshaft) the wrong way around. Pre internet days….
Surprisingly it remained quiet for quite a while, but eventually the side load on the timing side G15 bearing caused it to fail.