ACT Streetlight flywheel buzzing/vibrating

[RayRay88]

Originally Posted by Pat

I just heard from the shop. They verified everything in the drivetrain looks fine, with the exception of the tranny. IIRC they stuck a scope in there while driving and saw movement around the TOB. We used a current OEM TOB. We scheduled more time next week to take it apart and figure it out.
To be continued...

Problem with the TOB or snout? AFAIK the snouts on these and other subaru tranny's are prone to fail/get damaged.

[Pat]

Originally Posted by RayRay88

Problem with the TOB or snout? AFAIK the snouts on these and other subaru tranny's are prone to fail/get damaged.

Good question. I am unsure. They will have to do more exploration next week.

[toast]

When I just did mine the other day there were witness marks on the input to the diff and what I thought was a matching one on the driveshaft. Turns out what I saw on the driveshaft must have been a sliver of light from my worklight, so I didn't have anything to line back up. I had a droning sound on deccel from 3500 to 2000 rpm. I marked where the shaft was and rotated it. One 90 degree change fixed it.

[Pat]

The shop inspected and replaced the flywheel and clutch today. Here are their somewhat inconclusive notes:

Excessive vibration while driving present. Ran vehicle on lift in 3rd
gear at 3k rpms and found increased vibration without load. Verified
driveshaft flange markings aligned. No excessive movement in
driveshaft. Used stethoscope testing rear differential pinion bushing,
carrier bearing and transmission. Found abnormal noise in
transmission only. Carrier and pinion smooth.
Used borescope camera to inspect clutch and release bearing.
Found release bearing doesn't ride smoothly on forks, has an off
rotation movement as though pressure plate forks are uneven.
To verify drivetrain after trans operation, moved driveshaft flange off
original position and test drove. No change in behavior. Based on
visual inspection suspect problem with clutch and flywheel internally.
Clutch kit removed and found clutch finger discrepancy and missing
alignment dowel pin. Clutch and flywheel has abnormal wear on
outside only from spinning off centered. Replaced clutch and
flywheel and missing dowel. Assembly reinstalled and vibration
problem greatly reduced at this time.

[shrug]
It's not as smooth as OEM, but that's not entirely surprising. I'd say the NVH is reduced by 80% from where it was previously. Good enough for me.