Bearing in MT start failing ?
 

Good morning,

After some recent tuning on dyno, some kind of short squeaking noise started to appear when the trans engages when releasing the clutch, right at the friction point, mostly when engaging into first from neutral, but it happened up to 3rd so far, particularly when car is warmed up. The noise stops as soon the clutch is fully engaged. Sometimes I will hear it also when I disengage the clutch to go to neutral, again right at that friction point. The tech listened to it on the lift and noticed that likely some kind of bearing may be doing that noise in the tranny. We changed the tranny oil (redline), but so far it does not seem to help.

I’ve had the car 7 years and never had any such problem before. This has nothing to do with the normal “quirks” of our beloved car tranny...

Has anyone experienced similar issue ? Currently I am contemplating finding a used MT with low mileage on it as a replacement, as true swap options like cd009 and rebuilds are much more expensive and seem to have their lot of downsides too. However, I would appreciate getting a better understanding of what the issue might be before jumping to a solution...

My car is a 2013, 120k km on it, turbo’d at about 310whp/260wtq since last year, but Forced induction with 270whp/210wtq has been there since 3 yrs at about 60k km. Clutch was changed last year to stage 2. I normally drive it very smooth however, and rev match my shifts most of time. Had a few hpde days in the last couple years. It had several dyno runs too for tuning.

Thanks

Is the tob original?

I would say so, unless it would get changed during a regular clutch upgrade, it is original. It not clear that the symptoms I have line up with any TOB problem. I do not have any “tractor” noise at idle, and (so far at least), the noise only occurs in the first/last inch or so of pedal travel where the clutch engages/disengages, and only if I’m putting it into gear (not in neutral) The fork was also greased, and it did not solve the issue. The noise is confirmed to be inside the tranny.

Are tranny mounts stock? Though my first guess would have been TOB.

I had the same issue with mine started chirping every time I engaged the clutch. There are a couple of bearings that wear over time that may cause the issue and can be changed. At almost 8 years old (140000 km's)I decided to just swap out the entire clutch. Problem solved. Car feels brand new

Yes, tranny mounts are stock, the one thing that was added after FI was replacing the stock rubber transmission mount bushing with a stiffer polyurethane one to reduce sway because of the increased torque. This was done last year and really made it much smoother, but increased cabin noise a bit.

Thanks for the feedback. did you swap out out just the clutch, or the tranny also ? In my case, the clutch and pressure plate are only 2 yrs old (35k kms or so)

falcon_wizard: try reverting to stock bushing.

Does the noise happen when you hit big bumps? Do you have a launch control function where you can hit the artificial redline and hear the noise happen?

My “transmission” has been “failing” for the last 20k miles and I’ve been waiting for someone that has the same problem.

The only time i have noticed it so far is when engaging/disengaging the clutch. I do not have launch ctrl, and have not been driving to redline for the last while.

I’ll try to make a small video where it can be heard well, but it only happens when the car is warmed up.

Do you think there would be a condition that would make that bushing suddently be problematic ? It’s been fine with it for over a year, and the issue just recently appeared after a dyno pull. Maybe it moved and would cause a mis alignment only when warmed up?

falcon_wizard: poly bushings still pass/amplify lot of noises to cabin that otherwise would have been dampened. Further it's made worse, if there are also at other transmission driveline stiffer bushings, eg. stiffer engine mounts/diff mounts and so on. Then you may also hear noises caused by eg. clutch/diff. Many of bushings might be of acceptable impact to NVH by themselves, but often in addition to others summary result is much worse, because when just some of bushings are changed to less compliant, often large share of noises gets passed somewhere further where still compliant bushings are .. but if those are stiff/more rigid aswell, it gets worse.
I have perrin poly transmission mount & bushing combo. In addition to some SC-like gear whine in lower gears i have also something that sounds like "gear rattling" when i go over some potholes/road defects. They went away when i reinstalled stock rubber bushing & mount for gearbox. I still decided to use those poly bushings for better gear shifts, but i need to accept that rattle noise as given.

Understood. When I did install that one trans bushing, It did transfer some whining noise from the trans particularly in 6th speed, and I hear small noises clearer, but as you say, I accepted that as trade off for the added stiffness. Without it, the trans would jerk when shifting gear due to the added TQ, and I was more concerned about that. The squeaking noise I now experience was never there before, and no added bushing or other mounts were changes when this came up. The mounts have been the same for about 10months and over 15,000kms. I’ll still check to see if it may have shifted during the dyno pull, or was otherwise damaged, who knows.

Imho most squaking noises from there are more often related with clutch. Hence my main suspect being throwout bearing. I'd change that (ensuring that it's updated one (toyota SU003-07349 or subaru 30502AA150) and maybe relubricate fork/pivot friction points and such, and as changing TOB requires dropping gearbox, inspect in general clutch state. Car has forced induction overall, so greater load/wear on clutch.