M47 Conversion: noise reduction

Just completed the conversion from 3sp auto to M47 on my 245.

Car drives fantastic, shifts smooth.

But there's a whine, almost electronic, not unlike an alternator, that increases with RPMs. It's loud in 3rd and 4th gears, and almost disappears in OD.

Once I'm out of OD, the whur/whine returns.

I think I need more insulation?

Is there a foam block kit that assists this?

Or should I run a different gear oil?

Or, am I screwed?

An M47 is a straight 5 speed no OD.

Redwood Chair said:

An M47 is a straight 5 speed no OD.

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Oops. Sorry. M46. New to this.

Strange 4th is 1:1 or straight thru the box so there shouldn't be 'gear' noise in 4th.

Two things (which don't address the root cause)
1) if you don't have the fitted OEM foam block that fits inside the shifter hole - just get a cheap foam car-washing sponge and cut a small hole in it, then stuff that down into the gap between the trans and body. Less heat, less noise.
2) I made the T5 in my wagon (not the same thing at all, of course) quite noticeably quieter by changing the shift knob from a solid hard plastic round knob to a leather-wrapped knob with a little sound deadening inside. The stick vibrates, but the knob is one of the ways that vibration gets turned into noise inside the car.

It could be the OD clutch bearing. When OD is engaged, the clutch is pulled against the brake ring and it stops spinning.

I have the foam shifter seal in stock.

http://forums.turbobricks.com/showthread.php?t=307928

I created a video of the trans noise at speed. It's that synthetic-sounding noise. https://youtu.be/VFoikXw1l58

Yeah that sounds rough. Hard for me to tell really where it's coming from. Hope someone else has some insight for you.

intothelabyrinth said:

Yeah that sounds rough. Hard for me to tell really where it's coming from. Hope someone else has some insight for you.

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I'm thinking it's a bearing