E46 323CI clunk noise from the back and jerking/twitching

[Tampepunch]

Couple of days ago on my way to work I pulled out from a gas station, pretty much floored it to get out on to the main road as there was heavy traffic and i found a spot between some cars. Directly after that I started noticing what started as a "scraping" sound, kinda like if something was rubbing up against a tire. During the next 10 seconds it became worse, and began to develop into a "clunk" noise. Just a second later, for every "clunk" noise, the car would jerk/twitch as if one or both of the rear wheels would, just for 0.2 milliseconds, lock up and then release again. It did this no matter what I did, give it gas and it clunked and jerked, brake and it would clunk and jerk. Go straight or make a turn it would clunk and jerk. No matter what I did, the car was behaving like this.

But then, all of a sudden, it stopped. Tried everything, and I mean everything, to make it "do the thing" again but to no prevail (I was trying to see WHAT part of my driving it was, causing the car to "do the st00pid" to try and figure out what the fault might be).

And then, it started again for a while. And then it stopped for a while. And then i started again. And it's been going on like this for a bit. I've searched to try and find someone who experienced this but it seems from my searching that I am alone in this specific situation. I've seen plenty of threads about "clunking noises" but never about one where the car jerks as it does the sound.

The sound is definitely coming from the back. And as I said, it jerks (not very hard but still) whenever it makes the sound.

Can someone PLEASE enlighten me with your knowledge and at least just give me some pointers as to where I should start to troubleshoot/investigate.

Could it possibly be the brakes? I changed both brake disks in the rear and pads all around like a week ago. The PO never noticed anything like this, so the brakes is the only thing that has been touched on the car, so other from that the only options is something either coming lose or breaking...

[MarcoZandrini]

As you may know, the E46 has problems with the sheet metal where the rear axle carrier bolts to the car. Basically, the engineers at BMW specified sheet metal that’s too thin for this area. As a result the sheet metal tears. BMW corrected this issue by installing thicker sheet metal in this area. The thicker sheet metal was installed in the model year 2002 E46s.

You need to get the car up in the air on a car lift to properly inspect the sheet metal. Repair of torn sheet metal is expensive as the rear axle carrier has to come out so that the torn sheet metal can be fix by welding in metal plates.