Originally Posted by Stang70Fastback
I think perhaps I wasn't fully clear in my explanation, though it's possible I'm still misunderstanding something, as I'm not yet an expert in these things. As I understand it, if my car is sitting still, clutch OUT (not depressed), with the transmission in neutral, the input shaft will be spinning along with the engine. If I clutch in, this disconnects the engine from the input shaft, and it stops spinning. If I then release the clutch, the engine is again reconnected, and the input shaft spins up again.
Correct.
In my case, I hear the whine when the car is sitting, clutch out, in neutral. I press the clutch, and the sound goes away. I release the clutch, and the sound "spins up" along with the input shaft.
That also just happens to coincide with loading and unloading the throwout bearing. How long does this "spin up" take? The input shaft will go from stop to engine RPM in a fraction of the clutch travel. It should be nearly instantaneous. If it takes longer than that, it is not the input shaft you are hearing. That does not necessarily rule out an internal transmission issue, but it rules out the input shaft bearing.
Also, when I shift from 1st to 2nd, the input shaft abruptly goes from spinning at 5k to spinning at 3k RPM. I can HEAR this in the form of that whine abruptly spinning down in a similar fashion as I push the gear shifter into second.
Now, you said that the noise goes away clutch-in. You presumably have the clutch in when you are shifting...? So describe this a little better... Does the noise suddenly come back? but only during the shift? Because that points to another problem entirely.
Unfortunately, I am not in a position to easily pull the transmission (in fact, I've never done that before.) What you are saying makes sense, but I would think that I would get at least some sort of noise with the clutch depressed, if the throw-out bearing was failing, no?
Not necessarily. Adding a thrust load to a worn or failing bearing can silence it, for largely the same reason that pushing on a loose, rattling panel can stop the noise it's making. In fact, most people reporting TOB issues say the noise starts clutch-out after cold start, and only progresses to happening clutch-in when it gets really bad.
Also, if it's the latter, then that makes sense too, and I'd be totally okay with it if it's just a result of the transmission being "broken in", but as I said, I doubt it is a case of gear whine, as the sound appears to be independent of the actual gears in the transmission.
It doesn't have to coincide with the actual gears; consider this... All the gears in the transmission are in constant mesh. They are all spinning at the same time, and they are all in mesh regardless of the selected gear. 2 pairs of gears carry the load at any given time: the selected pair on the layshaft and output shaft is the first pair, the second is the the input shaft gear (there is only 1 gear on the input shaft), with it's corresponding gear on the layshaft. The latter pair carry the input load regardless of the selected gear. With the exception being in fifth gear, as that connects input and output directly. 1:1 Oh, I forgot to ask, does the noise go away in any gear?
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