1987 325 is - Vibration after Transmision replacement

Hey Folks,
I just had my automatic transmission replaced. At about 20-25 MPR a loud vibration starts between the center console and the passenger seat.
At first I thought it was something in the passenger door, now I'm pretty sure it's not. It's hard to tell from the drivers seat.
The vibration sounds like a worn out fan motor. Of course, there's nothing like that under the car. The vibration starts at 20 mpr than completely goes away after acceleration and does not increase in velocity when I accelerate. It just goes away. The car and trans work exceptionally well.
I have a call into the mechanic, and I'm waiting to hear back from him.
Any help here would be greatly appreciated.
TIA
Lance
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It sounds like your mechanic seperated the driveshaft while it was out and didn't put it back together in the correct orientation. Doing so can put it out of balance causing vibration. A driveshaft is balanced assembled, and the sections must not be misaligned.
Other posibilities are loose or improperly installed driveline parts such as transmission mounts, guibo, or center support bearing.
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I agree, the first thing that springs to mind would be the propshaft. Although, I would have expected more of a vibration at around 60MPH (100KM).
Of course, without hearing/feeling the noise, it's difficult to comment. So, it could also be a vibration/resonance from the exhaust, heat shields, etc.
Let the mechanic have a look.

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Were you billed for a new guibo? It might have been a good idea just to replace it when he was in there.
Another possibility is that the driveshaft was not reassembled with everything lined up perfectly.
Should not be a huge deal for the mechanic to fix. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Thanks so much for the feedback. looks like it was driveshaft calibration. Problem easily solved!!

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