Well, I was cruising around today when I noticed that the car felt like it was shifting strangely, just like the shifts felt a little more pronounced then normal. The car was in sport mode, so I put it in comfort mode, thinking that might make a difference. After changing it into comfort mode, two stop lights later, I tried accelerate but the car did not move but instead started violently rocking back and forth. Not merely like a rough idle kind of uncomfortable feeling, but actually jumping back and forth (the car did not actually move though). After that incident, I drove another 10 miles or so and it ran fine, though I'm scared something major might be one the verge of happening. Does anyone have any ideas?

sounds like a tranny fault, may be not engaging properly...it happened with me but not on a bmw . it was a feeling like it was missing but it was the tranny. i hope it is not on yours...

Try driving with the traction control off.

I have had the traction control do that on wet pavement on a newly painted turn arrow. It may be alternating locked brakes in the back.

Something that has been on going for a few years now, not that I know if it's related, is when I shift the car from Reverse to Drive or vice versa it doesn't engage, then a few seconds later it does(keep in mind I'm not giving it any gas) and then it gives me a huge KICK, like I popped the clutch my first time driving stick and this is on an 840Ci :(. It's very sporatic, but I still hope it's not a precursor to the end.

I wish you the best of luck on this one,
Thomas

I would start with fluid and filter change and make sure that it is filled to the correct level. That may be a good start.

Hope this helps.

For the 5 speed automatics there is a ZF valve body kit that replaces the worn out original plastic balls to keep them from sticking.

This covers all 840's and late 850's

For the 5 speed automatics there is a ZF valve body kit that replaces the worn out original plastic balls to keep them from sticking.

This covers all 840's and late 850's

More info, plz! :).

Call Kirt Koeller here http://www.autosportsunlimited.com/

He was the first to bring up availability of the kit a few years ago when it was a new thing.:)