540i/a Shifting

[Phatty5BMW]

how cold is it where you live?

It was about 30 or so this morning, when he drove it, it was about 45 or so? somewhere near there.

[charlie]

What is "reflowing the solder joints" all about?

I agree. Other than the shift selector, there are no mechanical controls such as cables or vacuum modulators. It's all electronic.

I had a minor shifting problem with my 540 (the torque converter lockup, really) and talked to Kirt about it. His primary recommendation was to reflow the solder joints in the control unit. Beyond that, he said, drive it til something worse happens.

In my case, the reflow didn't help as much as a Dinan trans chip (I still think the resolder is worth a try).

BTW, those M60 drivers with Alusil replacement blocks and slightly erratic transmissions may want to open up their transmission control units for a look at the chip inside. My car had a chip that did not resemble the one Dinan told me to expect to find.

[MBXB]

Reflowing a solder joint involve reheating the joint and getting the solder to completely reflow to make the connection secure.
Joints can get intermittent due to vibration, temperature or a faulty solder flow to begin with (called a cold solder).

[Ross]

If "gear hang" means that it shifts a bit late when cold this is normal.
The higher revs help the cats light. It's painful to hear a cold engine rev like that I know.

[charlie]

but where? in the transmission?

Reflowing a solder joint involve reheating the joint and getting the solder to completely reflow to make the connection secure.
Joints can get intermittent due to vibration, temperature or a faulty solder flow to begin with (called a cold solder).

[Mr._Graybeard]

but where? in the transmission?

The control unit is under the black cover near the firewall on the right side of the car, along with the ECU and (IIRC) the ABS control unit. You'll see the cover is in its own little compartment in the corner of the engine bay opposite from the fuse box.

[MBXB]

http://www.bimmerboard.com/forums/posts/356031