Transmission noise upgraded from 'concerning' to 'alarming'

[anarchy1024]

Hi transmission people,

I recently started getting an alarming noise from the transmission, which I'm guessing is something with the input shaft. Whenever the clutch pedal is released (any gear, any speed, including neutral), there's a "chattering" noise. When the clutch pedal is depressed, the noise stops.

The noise varies based on engine speed and transmission load, not road speed. The noise is present when engine braking and accelerating, and is louder in lower gears. When coasting with the clutch pedal in, the noise disappears, regardless of engine or road speed.

The noise probably started sometime last year, but was very quiet (barely audible). It only became this bad after a spirited drive, where the drivetrain was under unusually high load. The clutch, flywheel, pilot bearing, throwout bearing, clutch fork, slave cylinder, clutch fluid, and gear oil have already been changed. There's no noticeable problem driving the car, or with the feel of the shifter, clutch pedal or anything else (that I can tell).

I recorded the sound that the transmission is making, with a microphone placed right beside the transmission (it's just a USB headset, but hopefully it's clear enough... you might need to turn down your volume as it's quite loud):

Driving:
https://goo.gl/photos/HrZzN6aXmNihExoi7

Revving (Transmission Audio):
https://goo.gl/photos/TfL4CUbk9YNySUda7

Revving (Interior Audio):
https://goo.gl/photos/MtAuc7E5Z4GWBTew9

So, I've gotten myself a second car that I can use in the meantime, since I guess that continuing to drive the Baja would be bad. Short of buying a new transmission, where would be a good place to start?

I'm guessing it's the input shaft bearings, and if so, it looks like they might be relatively easy to get to using these directions:
http://www.ultimatesubaru.org/forum/top ... placement/

Thanks!

[anarchy1024]

TL;DR version:
After a spirited drive, the transmission has a 'chattery' noise when clutch pedal is released (all gears incl. neutral; all speeds incl. stopped); disappears when pedal is pressed (not just touched). Noise varies with input shaft/engine speed, not road speed. Already have new clutch, flywheel, pilot bearing, throwout bearing, clutch fork, slave cylinder, clutch fluid, and gear oil. Videos above recorded with a headset microphone placed beside the transmission.
Thanks!

[Acro2pilot]

It sounds like your on the right path, and what I think you already know is that your going to have to drop the tranny, split the case, and get eyes on the problem. As available as these transmissions are, it might be justifiable to pull a used unit and do a swap so your downtime is only an afternoon. You could pull the original apart at your leisure and have a spare.

[anarchy1024]

Yeah, the plan is to drop it and check it out inside to see if the problem is obvious. If I can find a used transmission for under $600 I'll just get and install it, but I bought a second car to use as a DD, so I can take my time with the Baja. I want to do as much myself as possible, mostly for learning, but also so I can say it's my Baja, if that makes sense.

Anything I should be aware of when opening it, look out for when I'm inside, or change as preventative maintenance while it's apart?

[Acro2pilot]

Drain it and let it drain overnight, every drop you get out makes life that much easier. Photograph everything as you go. Replace seals while your in there, and once it is back together check the function before putting it back in since it is not fun to find a fork was misaligned after the tranny is fully installed back in the truck.

[anarchy1024]

Cool, thanks!

Finally got started taking it apart, and I think I found the problem:

image.png (462 KiB) Viewed 5937 times

Since everything else is tight with little-to-no play, and this one has lots of play, is it safe to say this is the cause?
Video: https://goo.gl/photos/SfhaRqFU3VHNLTy37

This one doesn't look easy to replace... seems to require a press and other tools that I don't have. Is that right?

Also, what's the best way to clean the inside of the transmission? Compressed air?