4th gear whine

[maestromaestro]

Had the transmission swapped with a donor one, which went through a rebuild. The rebuild included bearings, but the gears were “out of scope”.

So, now when I’m in the 4th gear - and it is limited to only the 4th - I hear a high-pitch whine.

Any thoughts? Really loathe the idea of removing the tranny again and opening the case....

 

[TyphoonFiST]

Who did the rebuild?

 

[maestromaestro]

Who did the rebuild?

The shop I trust. My question is what this noise means...

 

[TyphoonFiST]

What fluid did you fill it with? and how much?

 

[maestromaestro]

What fluid did you fill it with? and how much?

Right. So - mostly Ravenol 75w. Had to use a bit of Lukas to top off; should be very close to 2L.

 

[TyphoonFiST]

Could it be the Carrier/ axle shaft bearing on the passengerside Cv axle?

 

[TyphoonFiST]

Since the Trans was just basically rebuilt.... that's one bearing that comes to mind. I just find it hard to believe the trans is bad already.

 

[maestromaestro]

Since the Trans was just basically rebuilt.... that's one bearing that comes to mind. I just find it hard to believe the trans is bad already.

It started making the noise immediately, during the post-install test drive. So, it’s likely something that I “inherited” with the donor. My question is whether it needs to be addressed or is harmless. Also, what the culprit may be.

 

[TyphoonFiST]

Hmmm...that's a good one

 

[Questionable]

I've had a similar issue that happened to several transmissions. It was annoying, but never affected how the transmission shifted. Was the donor car tracked or raced at all?

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[maestromaestro]

I've had a similar issue that happened to several transmissions. It was annoying, but never affected how the transmission shifted. Was the donor car tracked or raced at all?

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I wish I knew. It was, allegedly, from a 30k mile car. Junkyard sourced. When the case was opened, a bunch of shavings were found. Rather than send it back, I decided to have it rebuilt. But, we never touched the gears.

 

[Questionable]

Sounds like the third transmission I had in my 2014. I got two transmission replacements under warranty, then I put an LSD in the third trans. So when I got the whine again I took it to a good transmission guy with specific instructions to figure out what's going wrong.

When he took it apart he found shavings and only 4th gear eating itself. He's been doing this a long time and said it was really weird wear because the synchros were fine. His best guess was my dual-mass flywheel was smashing 4th when I was shifting particularly roughly (loaded up in a turn shifting from 3rd to 4th).

New gears were put in the transmission (no upgrade parts available), the tolerances were made as tight as possible, and I was told to consider replacing the OEM flywheel with a single-mass one. I changed where I shifted on track and eventually replaced the flywheel with a Spec unit. I haven't had the issue come back.

The other guy in my track group who runs a 2016 Fiesta ST shifts where I used to and hasn't had any issues like this.

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[maestromaestro]

Hmmm ... I had a new flywheel (DM) put in as part of the whole shebang. Given that it started with the whine immediately, it can’t be the new FW. Unless the donor car had this issue - we really couldn’t find any MAJOR problems with the bearings, but there were shavings found....

Really would hate to take the whole thing apart again.

 

[Questionable]

Oh, I didn't mean to imply that your car caused the issue. I meant the driver(s) of the previous car might have had a bad flywheel and made some rough bad shifts like I had.

The whine in my car never got worse *except* when I made rough shifts from 3rd to 4th on the track. And it never affected how the car shifted, just how annoyed I was when driving in 4th gear. I just dealt with the whine for 6-ish months until I got annoyed enough to pay for having everything torn apart to diagnose. I didn't have any sort of catastrophic failure that forced me to do the rebuild.