Same here! 545 step - or maybe SLAMTRONIC!! Happens about twice a month.

That said, the E39 did it at speed. If I jumped on it at about 75 - 80 MPH, it would slam hard when it downshifted.

But the E60 does it only at low speed.

 

This happened to me also. October 2004 build 545. Just once in 4500 miles, but it scared the crap out of me. I was creeping on a metered freeway merge ramp and thought I'd been hit by a truck, but the closest vehicle was way too far away for that. I think I am going to go in for 16.2 upgrade for this and several other oddities, like no bluetooth in the iDrive comm menu.

 

Ha! and I thought I had problems wiht my SMG... (same type of banging) LOL Where's CIP 16.1??? GRrrrrrrrrrrrrrrrrrrrrrrrrr

 

I had it, but haven't felt it in a while. BMW service says transmission is functioning normally. Low speed transmission slam is normal? I doubt it.

Maybe after it breaks in, it stops doing it?

 

My dad has a 545i steptronic and he has the same problem happened about 10 times he said its like feeling 325hp in your back teeth. im going to have him go down and get software 16 when i know that it acctually exists.

 

Happened to me today. My god!!!! It felt like my head was going to snap off. It happened as I had just slowed down to stop and then took off before the car came to a complete stop. Then BAM! What is up with this?

 

mine is currently in the shop...and this is one of the problems being addressed...dealer told me it needed a software upgrade to fix the problem...i asked my service advisor if the software upgrade was a known fix to a known problem or merely an attempt to rectify the situation. And she (the advisor) told me she would check with the tech and let me know...they still have the car in that they need to finalize the install of my steering rack...when I get the car back I'll let you know

 

Here's a possiblility on what's happening (at least in the case of ledbettm but possibly others)...

I've been saying for a while now that in my experiences, I've found that downshifting the SMG before the car does it for you seems to work better. The main reason I've said this before is that by downshifting yourself, you maintain control of what's happening with the car. If you let the car downshift when it has to but you then decide to accelerate (as ledbettm described), you catch the transmission "off guard" because it was in the middle of downshifting but you're telling it to accelerate. (I've experienced behavior similar to what ledbettm and others are describing back when I was first figuring out the best way to drive the SMG.)

In my earlier posts on this subject, I used the analogy of pulling up to a stop sign but never coming to a complete stop (as many of us do on some deserted side street, for example.) I always downshift into first gear around 2000-2500 rpm as I'm approaching the stop sign. That way, I can gently ease off the gas and/or modulate the brake as the car is slowing but if and when I'm ready to accelerate, the car is already in first and ready to go.

Here are some links to my earlier posts on this topic:
http://forums.e60.net/index.php?showtopic=...932&#entry51932
http://forums.e60.net/index.php?act=ST&f=2...st=0#entry59189
http://forums.e60.net/index.php?showtopic=...147&#entry69147
http://forums.e60.net/index.php?showtopic=...190&#entry69190