My understanding of my recent barn find is that the transmission was rebuilt and was never driven after.

It does run great and shifts nicely, but there is a steady whine which appears to come from the transmission when cruising. At 55, while applying just enough gas to maintain speed, the whine is very annoying. It does it in all gears, the pitch increases with speed, and is quiet when coasting.

Two extra transmissions came with the car, one looking like it was a donor, and the other looks untouched. I cracked the untouched one and examined things and the ring and sychros all looked pretty good, so I swapped it in. Magically, no whine, but grinds when shifting into 1st.

So I cracked the one that whines and found that the pinion and ring gears are mismatched. One is marked 617 and the other 240. I opened the donor and found that they were also mismatched, but I now had gears from 4 sets, there were no two that matched.

So I pulled the transmission that ran quiet and its gears matched. So I swapped the gear stack between the quiet one and the whiny one, and now had a transmission with all good synchros and rings, and matching pinion and ring gears. I was very proud of myself to have identified this issue and found a resolution.

So I installed my new creation and it ran great, shifts beautifully, and still whines!

By the way, all new transmission oil installed using Red Line 75W90.

Any thoughts would be greatly appreciated!

Are you sure it is a noise from the transmission? It would be an unusual problem, likely an assembly issue since it has been apart. The rear wheel bearings can sure make some noise when they're failing. The noise will change with veer toward left or right if its only one side going south. Since your noise is present when under load, rear whl brng problem may not be a good guess, but worth checking.

It's the Ring/Pinion matchup that creates that whine. I'm no expert, but have heard that Porsche assembled the transmissions and ran them on a test stand and selected the intermediate plate gasket thickness that minimized the noise from the R/P. Since you've had yours apart and did a mix/match you may have gotten the R/P off of it's sweet spot....
I'm sure some better qualified folks here can chime in....where's Dr. Evil when we need him??

Rear bearings were just replaced. Whine was present before and after.

I thought about the gaskets. Only one was present but I have no idea whether the previous owner paid attention to the gaskets when he rebuilt it. Since setting it properly requires some tools that I doubt I could obtain, I guess I could try adding one gasket at a time to try to find the sweet spot. But what a pain.

Any better ideas about how to go about this?

Before you get carried away with more complex solutions, have you tried a heavier tranny oil like 85/140? It quieted down my trans considerably with no ill effects.

This is what I found when mine started whining on my 6!

Bummer, but all the bearings look good. It's got to be a mesh issue, and most likely the pinion / ring mesh.

Does it change tone or pitch between accel and decel?

No noise on decel but pitch does change with speed.

Don't know about decel by down shifting because engine noise is louder.

Those "gaskets" are technically shims, I think. I think the basic clearance was in the general range of .1 to .3 mm. And John may be correct about that being the cause.

The correct procedure is to mic the old shim/gasket in a spot where it's not been compressed by the case and replace it with one or two new ones that closely approximate the original within .003 inch (or mm?). But if whoever took apart the case previously never bothered to do that, you're basically just guessing until you can get it right, and that does sound like a real pain .

Hopefully it's something easier...

Sounds like you have all matching internal parts and made excellent progress.
I believe you now have to do a basic setup of the ring and pinion because you have installed them in a random housing.
You sound like a guy who'll get through it with insight and perseverance.
AND a manual.

Differential out of adjustment, yes gasket is shim but there are other adjustments.
Backlash is indicated on the pinion, there is a specific methodology for this adjustment.
With a stock tranny measurement of the gasket gives the backlash.
Mix and match produces problems ie whine and wear.
Factory repair manual has the procedure.
Mike

^^^^ Yes it probably needs to be realigned. Have to smear that grease on it and checked contact. I had this problem with my 5MT trans. Mine was missing a shim and it only whined on decel. Take a look at the bottom of the page on this link for an idea of how a trans is aligned.

Tooth contact alignment (bottom of page)

Dr Evil could probably fix that for you.

Check the bearing race deep in the case for the pinion shaft to make certain it has no damage. Hard to see, but older cases do have issues with that bearing and race when the wrong setup is put together and run for too long.

That's an interest procedure. The procedure in the factory manual involves some very special tools. I'll give this procedure a try.
Thanks

Chris,

The Subaru procedure you provided worked perfectly, although it took some patience! I had to open the transmission, paint the diff gear with blue dye, reassemble with different size shim, torque everything down, use a motor to spin the transmission, open it up again and inspect the gear mesh. I had to do this 4 times before I got the mesh correct, and like magic no more whining!

See pic: http://dolimpios.com/gear_mesh.jpg

I learned that method on muscle car differentials in the 80s. I was the only guy in my high school that could change the ring and pinion in a diff and not have it whine.

Just follow the directions to the letter. Don't try to take shortcuts. You can stop the whine if you work at it.


BTW...... Betty's car has a slight whine, but that is due to 400K on the clock, not improper assembly.

I have the same sort of whine in my gearbox and it was recently rebuilt. It did whine alot more before the rebuild and the builder changed out a couple of bearings and synchros. The whine is most apparent in 4th gear which of course is the gear I mostly use. I talked to the builder and he thinks the 4th gear is simply worn.

Not sure wether to live with the whine or have it torn down again.

I have the same issue post rebuild with a new bearing. Was told that it was likely "wear on the R/P from bad bearing" (meaning the old bearing).

Wonder if the setup procedure described here wasn't done...