HELP ME!!! Vibration - Shudder - Jerking after Transmission Replacement

[mejim707]

I desperately need help here. I'll try to keep this short.

I used to have a 2-3 shudder. The car was perfectly smooth other than that one 2-3 shudder. When I say smooth, I mean it. It was perfection. Highway was like floating on a cloud.

The trans was diagnosed bad from the 2-3 shudder. I got a used low milage transmission form a reputable parts location and had a reputable foreign transmission shop install it.

During the install they replaced both front and rear Guibos and Carrier bearing. All brand new BMW issued parts. And the install was correct. All aligned properly and the center bearing not installed upside down.

They used the Mechatronic form my original transmission since the computer is supposedly bonded with the mech and married to the vehicle. According to BMW you cannot reprogram the TCM form a used transmission so you have no choice but to use your original mech.

After getting the car back I had a shudder / shake appear at higher speeds from 50 - 75 mph. It would manifest when you pressed the gas about 20% or more. This increased to a vibration across all driving conditions as the car warmed up and as I used it. Then when you approached a stop a very heavy vibration / rumble would occur.

I brought it back and the mechanic diagnosed this as a bad torque converter. Under warranty they replaced the torque converter with a remanufactured unit from a reputable rebuild shop as well. The parts place, mechanic and rebuild shop are all highly regarded.

After getting the car back the exact same issue came back. So the shop took it for numerous road tests and was 100% confident that the issue was due to a faulty replacement transmission.

So the parts shop got a new transmission that was even less miles than the other. I got the car back today, it was smooth as silk out of the shop. Got on the highway and drove about 10 miles when the 50 - 75 mph shudder / jerking came back exactly the same! The heck??!!!

1. Cold and low speed up to about 45mph everything is smooth.
2. Warmed up in park there is no vibration.
3. Warmed and in gear there is a heavy rumble.
4. Press gas the rumble increases slightly then goes completely away.
5. As you increase speed the acceleration feels slightly crunchy, inconsistent and rumbly.
6. Highway speeds at 50 - 75 with light throttle the car is pretty smooth.
7. Highway speeds at 50 - 75 as you press the gas around 20% and more the whole car shakes, sometimes heavily including jerking / rumble / shudder. Almost where it feels like something is spinning unbalanced. (This is not tire or wheel related. It's not a balance issue and not from alignment. That's all perfect and checked.)

This is a total freaking mess. I feel absolutely defeated. I'm in on this at over $5500 now and the car is far worse than ever before. It NEVER felt like this. It's absolutely trash.

I'm going to BMW in Bridgeport CT tomorrow to have the TCM reprogrammed. The shop said that if BMW reprograms the TCM it will "marry" the original mechatronic unit to the new transmission and my issue "will go away". So that's what I'm going to do. But I don't feel confident in this and it's going to cost another $200.

Any recommendations would be great. This is the 2nd replacement transmission and 3rd replacement torque converter and the car feels horrible and exactly the same with all of them.

This is why I hate bringing my car to mechanics. Here I am trying to figure this out myself after already paying about $5500.