Did a search but nothing conclusive. My Oct '07 build 2008 550 has very recently developed some transmission issues. Kind of like the slam issue I had on my 545 which was corrected by a software update. Happens in DS and/or Sport mode when slowing down and the transmission down shifts, hard. Feels like being rear-ended. Don't recall anyone seeing the same issue. Anyone with similar issue and if so the fix?

I think I've felt it a couple of times (not sure if it was strong enough to feel like I was rear ended though.)

99.9% of the time, I manually downshift (like I did with my SMG) so it really doesn't happen to me much. I'm due for a service in the next few weeks and I do plan on mentioning it to see if there's any software updates that may address it...

Thanks Rudy. I will try manually downshifting for a while. Perhaps rear ended is too strong a description, more like being tapped from behind. I'm due for service in a month or so, will also mention it then...

I have had it, just once... I posted the experience, pretty frightening at the time given the traffic situation and the car shutting down on me. A search will turn it up. I also found and reposted a discussion that included a supposed ZF engineer, who offered an analysis of the slam issue, and it made a lot of sense. Again, try a search, if you don't find it I'll try to find it again. Search on my name. By the way, I don't manually downshift unless I'm feeling spirited, and it takes peculiar circumstances for the Slam to occur (if the ZF engineer's explanation is correct).

Cal

There are many of us chasing this tranny slam problem, unfortunately for many of us the software upgrade does not solve the problem. My car have been reprogrammed at least three times with the newest software everytime and the problem is still there. Do a search here and you will find quite a bit of info. Good luck.

I was the dealer today picking up my wife's X5 and spoke to my SA about the transmission issue. He didn't know of any software updates but a service tech walked in as we were talking about it so we asked him. He indicated there was a software update to deal with harsh downshifts on my 550. Unfortunately I had to run and couldn't press for a SIB number or any real details. I'll see if I can get more details but my the issue is not worthy of a separate trip and my next service is three months away...

:thumbsup:

mine is back!!! :( :(