Transmission Diagnostic procedure
 

Well; after some careful thought I've decided to keep her so
I'm in the process of the "maintain my ride" mind set. Repairing
oil leaks, additional issues and any other nerve racking issues
before they become a problem. Thankfully my issues are very
few.

Now it's time to take on the transmission. I will not be doing a DIY
so here's the question. does anyone know an expert NORTHERN CALIFORNIA
BAY AREA east bay transmission specialist who can give it a through
check?

Weather I change the fluid will depend on recommendations from the
expert. I have read many threads regarding the pros and cons about
why one should or should not change the fluid so thanks in advance for
any suggestions in that regard. Right now First things first. I'm looking
for a reputable shop to carry out a diagnosis.

Yep I've got the once a year downshift bang which has not been solved
by software of driver reprograming so maybe that issue can be solved. :dunno:

Seriously; No one had a recommendation? WOW

I think the lack of response is due to the "live wire" topic, trans maintenance.

Best bet? Find a ZF approved shop and let them look at it.

BMW dealers don't repair transmissions but they may know of someone that does or the local BMW focused independent shop will have someone they use.

As far as the question to change or not to change the fluid--there are strong feelings on both sides. BMW says the fluid lasts the lifetime. When they do the transmission work I feel sure they will replace the fluid. Assuming that is the case, you won't need to make a decision either way for at least 50,000 miles.

Thanks for the suggestion. :thumbup:

I cannot believe that Q is asking for BMW advice. Even stranger, I cannot believe I'm in a position to answer, at least in part.

I have the 2nd to 1st gear bang as well. What's been beating me to death is that the issue only happens in regular drive mode, NEVER in S mode. Also, issue is in the least dependent on engine idle speed and/or trans fluid temperature.

Interestingly enough another member on Xoutpost recently updated that he deleted his factory water cooled trans line setup for an exterior mounted air cooled trans line setup and his woes are gone. Issue with that is depending on ambient temperature where one lives, the trans fluid may not warm up as it should when it's very cold outside. Unless you live in Quatar, the higher band of the ambient temperature scale should be fine with the external setup though.

That said, I'm going to do a drain and fill with factory fluid first and foremost. Simple procedure to do. Very easy to access the drain and fill plugs on the E53 4.6/4.4(same trans). If this does solve my issue, I'll post up and inform the crew. In the least I'm hoping for an abatement of this darned issue.

My "banging" also does not occur when the AC compressor is engaged, but that's more a function of idle speed me thinks. If this car had an accelerator cable, we'd not be having these discussions I believe. lol.