Whining of 915 Transmission

[HawgRyder]

I have found in the past that this is the exact problem when you mis-match gear sets.
Some spur gears are just plain noisy.
We used to have several sets of the same number of teeth gears...and would try them on a test set of shafts to determine the noise and mesh factors.
Staight cut gears are the worst for noise.
Lubricant can also have a big effect on the whine factor.
Normally...the crown/pinion set is the loudest...and even following factory clearances...they can still be very frustrating to get correct.
In your case (no pun intended), I would remove the crown gear and try the spin test...a stethoscope will be needed to find the loud point.
Bob

[Walt Fricke]

I've been told that the gear manufacturer for the Porsche R&Ps sets the pinion depth at least in part acoustically. Set them up in some kind of test rig, and move in and out until the least noise is heard (within some set mesh range), and then inscribe that setting on the gears.

[HKZ Bob]

Originally Posted by HKZ Bob

Here some more schematics.

Dear Forum,
here one reason I strongly assume of my whining noise.

Attached a picture of the fixed fivth gear.
Look at the worn out tooth of the fivth gear. The other side of the syncro ring does not look better.

What is the root cause for such wear?




BR
Bob

[bazar01]

Gearbox probably was ran in the past with low oil level or wrong gear oil.

[Walt Fricke]

Agreed - those gears are toast.

At this point, I'd suggest you open up the rest of the gear box so you can look at gears 1-4. If 5th is that bad, and it was due to an entirely inappropriate oil, or not enough oil, or both, chances are the other gears aren't in very good shape either.

The pictures of the ring and pinion gears, and the spider gears, didn't look as bad as these of the 5th, so maybe the gears inside are still OK.

Looking back, I see you (or someone) had this box all apart before, and replaced a whole lot of stuff. I can't fathom anyone putting a 5th gear as bad as this one back in, which raises the worry level for the others.

Well, I can fathom it, but it would be a conscious decision to live with noise, and the ever present possibility that a tooth will break off, and perhaps get caught in one of the gear sets. When that happens, lots of things break as the gears try to push the transmission case apart so the foreigh object (which is hardened steel and isn't going to crush) can pass through. And I suppose that when one tooth breaks off (even if the fragment sits harmlessly down in the bottom of the case)others will follow faster, as the loads on adjacent teeth increase due to the lack of the first tooth.

[HKZ Bob]

Here some more pictures

how can I identify if dog tees are worn out out the shifter slider is bad?
My slider shows wear paddern inside but what ist still OK and what is bad.










BR
Bob