Trans bearing whine vs gear whine?

[Garnet]

Before I dive into my gearbox I am doing some riding and listening.

When hot (warm this time of year) I have quite a whine, under load, that seems to be equal in all gears. It increases with throttle load, is less noticeable at constant speed and disappears when I back off. It seems to get less in the higher gears but I think it because I can't hear it as well as speed increases.

I have had boxes that where noisy in some gears and quiet in others, so I would think that that was gear noise. The pitch of this noise is RPM specific, so I am thinking input or intermediate shaft bearings, but it is a whine not a rumble. Could it be the gears on the input and or intermediate shaft?

Those of you who have replaced trans bearings, what where the symptoms that made you do the job?

[ME 109]

Not sure about the why and how of whining trannies.
Open it up and all will be revealed

My motivation for an overhaul was finding fuzz on the drain plug after not seeing anything for about thirteen years.

[Duane Ausherman]

I suspect that the drive gear is undercut. What did you find in the oil?

[robert]

I suspect that the drive gear is undercut. What did you find in the oil?

Drive gear is undercut? Interesting....could you explain that, haven't heard that term.
MW109 has the logical approach to the situation----open it up and find out.

[Garnet]

I suspect that the drive gear is undercut. What did you find in the oil?

By drive gear, are you reffering to the gear on the input shaft?

I have only put about 4000 miles on this box. I just changed oil and found the normal amount of paste and what looked like a few flakes, but nothing that I could feel between my fingers. After rubbing the drain plug with a clean rag I could find no evidence of the flakes in the cloth. Maybe it was just the way some of the paste was standing on the magnet.

[Ross]

I don't mind a good red wine.

[bbelk]

When I was bringing my 75 R90 back from its long slumber it had a very pronounced gear whine. The mechanic thought he could fix it with barrings and shims but when he got into it, he found that the gears were pitted. He suspected water in the box at sometime in the bikes history.

[Ken in Oklahoma]

Garnet, I'm wondering which gears whine. On the 5 speeds the first 4 gears are spur cut gears (as you probably know) whereas 5 gear has helical cut gears (for the main purpose of emitting no whine in top gear).

I reckon the same thing would be true of the 4 speed boxes, that all the gears except for high have spur cut gears.

I'm used to hearing whine in 3rd gear on some of my 5 speeds. I'm not sure but I think I remember hearing it in 2'nd gear as well. Could be more gears. Frankly, I haven't paid much attention.

Is the frequency range of the whine roughly as might be expected? That's a nearly impossible question to give meaning to, I imagine. I guess I'm trying to say that a very high frequency whine would cause me to wonder about the bearings. And a low, perhaps described as "rumbling" whine would cause me to expect something else (meaning I can't even suggest a possibility here).

The fact that you haven't found any "feelable" flakes or grit and see no metallic sheen in the oil makes me more comfortable about the health of you 'box.


Ken

[Garnet]

Ross: I prefer white these days, at least the next morning I do.

bblek: The box sat for many years before I bought it. There was only (very little) oil in it when I drained it, but that means nothing. You may be right.

Ken: The noise seems the same in all gears, BUT it is hard to tell in 5th gear as wind noise is starting to drown out all else.

It's is not supposed to rain much today so I think a couple of hours of testing are in order.

And I have to test out my new Xmas present.



BMW Pro winter gloves. The local dealer actually talked to me and had them on sale. Perhaps they thought the world was ending today.

[ME 109]

The fact that you haven't found any "feelable" flakes or grit and see no metallic sheen in the oil makes me more comfortable about the health of you 'box.


Ken

That does make things more of a mystery Ken. It is possible that the damage was pre-existing (before Garnet acquired the tranny) and the oil has been changed, removing evidence. However I found it difficult to remove all traces of 'chips and fuzz' even when the tranny is apart and shafts are individually washed in petrol to remove such debris.

I would think that a certain 'noise' can only be produced by one condition in the tranny. Suck knowledge of noise causes should be known by someone who's done a lot of tranny repairs. Perhaps ADV could enlighten.

But after all the inquiring and stuffing around, the tranny needs to be opened so.....