Gearbox (?) noise

[riceburner]

Hope someone can give me some advice on this issue.

I've got a "rough whirring" noise coming from somewhere in the drivetrain.

In Neutral, I can hear it.
In Neutral, when I pull the clutch in (dis-engaged), it goes away.
In Gear (any), (moving, natch!), with the clutch out (engaged), I can hear it
In gear (any), (moving or standstill) with the clutch in (dis-engaged), I can still hear it.
The noise changes frequency with the gears as far as I can tell, and (I think) changes with engine speed rather than road speed.

From this I am guessing that it's something in the gearbox itself, on the clutch side (as opposed to the final drive side), or possibly something to do with the clutch, on the gearbox side.

I've been hearing the noise for a week or two now, and I have a "vague idea" that it's slightly louder on the RIGHT side of the bike.

I've dipped my finger into the gearbox oil (changed at 60K miles, bike is now on 67K) and it's clean and clear still.

My main issue is that I now do NOT have ANY other means of transport - and a 23 mile journey to do on a daily basis for work (public transport isn't a valid option at the moment), so I've had no choice but to keep riding the bike.

Has anyone had anything that sounds like it might have been similar?

I MIGHT have a few days over Christmas during which I could strip the bike down - but not really before then. I know that getting to the gearbox/clutch is a major PITA and would take the bike off the road for some time. I also can't afford BMW dealership labour rates - especially for a "diagnostic" job.

[Laserr Boy]

Sounds like a throw out bearing to me.

[sweatmark]

There's no throw-out bearing.

Burner, hate to ask... any chance you're hearing the demise of clutch hub/transmission input spines? Sure as heck hope not.

[riceburner]

There's no throw-out bearing.

Burner, hate to ask... any chance you're hearing the demise of clutch hub/transmission input spines? Sure as heck hope not.

I sincerely hope not!!

I wouldn't have thought that would be a drawn out process though - last time that happened (previous bike at 30K miles) it was a sudden and catastrophic failure. This noise has crept up and has been constant for the last 500+ miles I think. (daily travel is 45 miles ish)

[Buckster]

I do not know, but...Did you check your clutch fluid? Not sure if it would cause the sounds you are hearing, make sure the fluid resevoir is full and didn't leak down into the slave. If it has, good chance the clutch will need to be replaced.

[sweatmark]

In gear (any), (moving or standstill) with the clutch in (dis-engaged), I can still hear it.

This finding seems most significant: if bike is running while on centerstand, clutch pulled in and friction plate disengaged from flywheel assembly... only rotating parts should be flywheel assembly and clutch actuation rod (and whatever wants to spin inside the clutch slave servo).

If the clutch slave is failing, then perhaps clutch disengagement is not complete... which would mean some power transfer to gearcase and rear wheel rotation despite clutch pulled in fully.

[riceburner]

In gear (any), (moving or standstill) with the clutch in (dis-engaged), I can still hear it.

This finding seems most significant: if bike is running while on centerstand, clutch pulled in and friction plate disengaged from flywheel assembly... only rotating parts should be flywheel assembly and clutch actuation rod (and whatever wants to spin inside the clutch slave servo).

If the clutch slave is failing, then perhaps clutch disengagement is not complete... which would mean some power transfer to gearcase and rear wheel rotation despite clutch pulled in fully.

Hmm - interesting. I have to say it does sound to me like something that's "outside" the gearbox oilbath. The noise doesn't sound "muffled" as it would be if it was within the gearbox oil.

I have to admit - in all the time I've owned BMs, I've NEVER touched the clutch.... (except to use it), and have only had one issue - where the slave piston rod became misaligned with the push rod somehow. That was under warranty though so I didn't have to do much.

Note - is there a clutch servo?? I thought it a purely hydraulic system with no outside interference??

Oh - there's no issue with clutch dis-engagement though, I don't believe.

[sweatmark]

Note - is there a clutch servo?? I thought it a purely hydraulic system with no outside interference??

No servo. I meant to type "clutch slave cylinder". Like you say, it's a purely hydraulic clutch actuation system... thankfully!

Seems I suffer from "BMW Integrated ABS Servo Over-Sensitivity", long after I removed the iABS from my Rockster.

If it was me, I would buy a replacement clutch slave and fittings (gasket? crush washers for banjo bolts?), remove the current unit for inspection, flush clutch hydraulics, and reassemble with current or new unit as required. Might take an afternoon's time? You would know where you stand with respect to the control-side of clutch before digging in further.

Good luck.

[riceburner]

Note - is there a clutch servo?? I thought it a purely hydraulic system with no outside interference??

No servo. I meant to type "clutch slave cylinder". Like you say, it's a purely hydraulic clutch actuation system... thankfully!

Seems I suffer from "BMW Integrated ABS Servo Over-Sensitivity", long after I removed the iABS from my Rockster.

If it was me, I would buy a replacement clutch slave and fittings (gasket? crush washers for banjo bolts?), remove the current unit for inspection, flush clutch hydraulics, and reassemble with current or new unit as required. Might take an afternoon's time? You would know where you stand with respect to the control-side of clutch before digging in further.

Good luck.

Worth thinking about certainly.

I still think it's something "at" the clutch though - it's definitely coming from that part of the drivetrain (ie it sounds like its coming from the clutch housing area).