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

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.

Any chance it is something that hasnt been replaced? Like a suspension component? Thrust bushes or control arms? Just a WAG. Doesnt really fit the symptoms



Report back what the TCM 'reprogramming' does. Personally I think the shop is grasping-



Finally, any thoughts on the transfer case?

Since the problem is absent warm stopped&park but appears as soon as you shift to drive, my money would be on the Transfer Case. As you fixed a 2 -> 3 shudder, the trans replacement was useful but it seems something else was disturbed in the trans swap. You eliminated the trans itself and the torque converter as a source of the issue, the remaining part common between these situations is the TC. At 250+k miles, this is quite possible. (Also my gut feeling is the TC fluid should be changed every 50k minimum but that is not part of this story.)


Reprogramming is indeed unlikely to fix the problem. But have the shop, that swapped the trans, drain the TC and inspect the fluid coming out closely. Also remove the TC actuation motor and gears, and inspect for proper functioning.

I brought it to BMW this morning. They did not do the programming. Instead they took it for a road test and came back and brought me to look.

They put it on the lift and with someone in the car they revved the gas, let off, then back on. The transfer case make a loud clanking sound / floppy chain sound and bonked around a lot. They did this a few times and said "We're 100% certain it's the transfer case. The chain stretched over time and it has far too much slack in it now."

Has anyone else tried something like this or do you know if a video exists showing how the transfer case should hold in place as the wheels are run off the ground?

But like you said, BMW is convinced it's the transfer case as well. BMW quoted me $8500 to replace it.

Nope! The trans shop is going to replace it with a low miles used unit for $350 with a 1 year parts and labor warranty next week. This will be a used 60k miles unit. They're hooking me up not charging labor because of how many times I've gone there and they should have been able to diagnose this issue there, and I shouldn't have had to go to BMW for it.

The good news is that BMW completed a full inspection and everything else on the car is 100%!

I'll update the thread on what happens after replacing the transfer case.

There you go.


I actually think there have been quite a few TCs reported on that other site... masquerading as tranny issues (so to speak)


I will comment that chains dont 'stretch'..they WEAR. As they wear, the bearing points in the chain open up and it gets longer. It isnt a 'stretch' in the sense of elastic deformation. As TriX had suggested, the fluid will prolly show you a ton of crap in it.


Report back!

:iagree:

Transfer case chains from all manufacturers can stretch with use over time, it's a maintenance item in a sense.

Update 2:

I removed the underside cover and unplugged the transfer case actuator motor harness. I drove the car without the transfer case engaging the front wheels and what do you know, the entire car feels brand new. Zero shudder, zero coasting shake and no more fluctuation while braking. This is 100% certain that the transfer case is the issue.

As mentioned, I have a "new to me" transfer case going in Monday or Tuesday. It takes about 2 hours max to do the job.

BMW Dealer quoted me $8500 for this, and they are trying to charge 9 hours labor.

But you know what, they did diagnose the issue and didn't charge me for the visit so they were honorable about what they did do.

Good that you now have a cause for the problem. From my perspective it is surprising that the guys who replaced the trans first time around were unable to diagnose this properly. They seem to be offering an olive branch by not charging labor for the TC replacement as well they shouldn't.....

So that's a good tip. If you want to run just 100% rear drive, you can always leave the connector off.