RPM-dependent gearbox whine

[nuclear944]

The singing gearbox...well who knows?! You have so many bearings in there.
My sedan's gearbox is original and it sings between 45 and 55 mph. Not unbearably, but noticeably. The throwout bearing also whines like crazy whenever the clutch is operated (especially under low load).
Sometimes I get angry at it and sometimes I tell myself that it'll hold. Never has jumped out of gear, but 1st to 2nd is notchy.
Maybe things will get better after a motor mount overhaul.

You shouldn't worry about yours if the gear changes are relatively smooth and non-grindy.

[euromobile900]

The singing gearbox...well who knows?! You have so many bearings in there.

You're telling me. I have a mental image of each one in my head as I'm driving.

Only the pinion bearings really have a habit of singing. Opposed tapered roller bearings seem to like to do this more than other types. It will sound just like a tuning fork, struck and put on something wood. That kind of "oooooooooooooo" sound that, when viewed on a 'scope, is a pure sine wave. Musicians? I read on the Netz somewhere that SAAB pinion whine had a pitch around middle C. That's the note mine is making. This has been somewhat confirmed by a friend whose 'box failed. Unfortunately, upon disassembly, it was found that his failed by shearing the teeth off of 4th on the cluster. Doesn't mean the pinion wasn't going too...

[nuclear944]

That is confusing as hell. I should get my guitar tuner in the car someday.

What makes them whine? And why oh why do they fail so prematurely as opposed to other manual gearboxes?

[drwatson32]

Case flex is a big part of it. Unfortunately, having experienced 2 manual gearbox failures, they both shifted fine before catastrophe struck. Check this out:


This had the C tuning fork sound. The teeth on the 4th gear & lay-gear, as you can see, sheered off going up a country hill, boosting 18psi.

[nuclear944]

Blimey! That looks gnarly! How did the failure manifest itself? What did it sound like?

P.S.(what happens in SC stays in SC)

[drwatson32]

Blimey! That looks gnarly! How did the failure manifest itself? What did it sound like?

P.S.(what happens in SC stays in SC)

It sounded delicious : p I've shown this to euromobile900, but might as well put it out there, given your question.
Yes, I've captured a gearbox failure on video : D You can hear what lovely condition things were in on the mic, though gear changes were nice and smooth up 'till that point. The neat thing was that just a few days before this video, I had just pulled a nice 69k mile gearbox at the Pull-A-Part, as I foresaw my fate.

[euromobile900]

It was only 4th, no? The newer gearboxes have a wider 4th to prevent this kind of thing from occurring. How fast were you going at the time?

[nuclear944]

Whoa. My gearbox is whining like that too on 1st gear take off. But it occurs only when the clutch pedal is depressed.

What's the deal with the clunking on clutch release in neutral? Mine does it too but I know for sure the pilot and release bearings need replacement.

[mbriet]

Great info on the part numbers!

I found that the SKF LM 48548 is a widely available equivalent to this bearing. Same applies to Febi 08950. Any taped roller bearing with b=35, B=65 and w=18 (in mm).

Alternate/OEM Part Number(s): 0K01126151, 10033592, 12309853, 1256028, 4338650, 5261231100, 53000475, 7451789, 7451790, 7451895, 7451959, 871086, 8710865, 8953000475, 9428059, E0TZ1244B, OKO1126151 (http://www.rockauto.com/en/moreinfo....=1835470&jsn=3)

Another Timken U298 equivalent list: http://www.pfibearings.com/CS_Custom...U261L&ssr=1771