Hey all,

Ive got a 4.0 mustang with all GT drivetrain, 8.8 rear end, aluminum driveshaft, freshly rebuilt tr3650..

Im getting a whirring/humming noise under load thats really got me stumped. Yesterday it was way louder than today, but I managed to capture the sound.. Its a bit hard to hear so I apologize in advance. I had to put my phone speaker up to my ear to hear it well, but in person its plently loud and annoying.

Its mainly only pronounced in 5th gear, and only under load. Heres the link..

https://youtu.be/4yRuryWhBZA

Is it typical for a freshly rebuilt trans to emmit these kinds of noises? Shifting is super smooth, and the ride is nice. I dont think its rear end trouble (fluid was clean), Im just hoping its not an input shaft, or maybe driveshaft imbalance/pinion angle.

The only thing that might make me think driveshaft, is that there is a roughly 1/2" spacer in between the engine/trans to adapt the 4.0 to the tr3650 bellhousing. And Im using a stock length GT aluminum DS.. So maybe pinion angle/etc could be a possible culprit.

TIA

 

*Bump*

 

I don't hear anything but exhaust drone in the video, unless that's the hum....
I do not hear a whine...

The TR3650 is known to be noisy, and are surprised you're not complaining about
noise it makes at idle with the clutch engaged. For some reason, behind the 4,0
engine, it makes odd noises. There is another post here somewhere about it.
My 4.0 and auto trans kind of growls at you, it's odd. It runs fine, has been, but
when you accelerate, it makes an odd growling noise. My son drive it once, he
has a 2002 and he was told me he noticed it too; he said "Hey dad, you're car
growled at me. I was like, WTF?" I just said yeah, it does that at low RPMs
when accelerating.

Could also be the aluminum shaft is carrying the vibrations from the trans and
emitting the noise. The only way to know would be to go back to the stock
2-piece shaft.