FFS I JUST GOT HER BACK TOGETHER. Rear diff mounting point is borked.

[03Z]

The mounting point for my rear diff mount is sheared in two. Like the space for the rubber bushing, has split in half and the diff is resting on the bracing and debris shielding underneath it now. Is this something I can weld or is it aluminum and going to require dropping 1k+ on a new rear subframe because they just had to make it all one piece?

I swear, these little things that BMW dropped the ball on is really gonna start to tick me off. first plastic for the shift fork pivot, now a mount where the guage of metal drops down two sizes and they essentially jsut make a strap instead of a properly reinforced mount.

[Steeler]

Are you talking about the snout on the diff cover or the steel tabs on the subframe??

[03Z]

Originally Posted by dbarton62

Are you talking about the snout on the diff cover or the steel tabs on the subframe??

the (hopefully) steel tab I suppose. the circular portion the bushing presses into is split clean in half so that the half of the circle that goes under the bushing is just gone. everything I've found so far suggests that it is aluminum like the subframe, and one piece with the subframe. so either I'm welding it, or buying a whole new subframe. if it's steel I'm welding it, if it's aluminum I can't.

[Steeler]

OK hold on, the subframe is steel
Get some pics

[03Z]

Originally Posted by dbarton62

OK hold on, the subframe is steel
Get some pics

Yeah I just realized anyone on the internet talking about the rear subframe and calling it aluminum is misinformed. Went out to the garage, jacked up the car, and stuck a magnet to it. Looking at this mount up close though, idk, steel or not this might not be a fixable deal. the back of it didn't break clean and I don't really know how I'd get my welder in there. here's a pic of what I'm looking at.

[Steeler]

Wow that is serious
You must have some very worn out bushings in the rear to get enough movement to fatigue that much.
IMO you need to replace the subframe. Don't know if you could repair that and get correct alignment for the bushing.

Edit, looking at the mess of that bushing I am not surprised the metal fatigued

[03Z]

Originally Posted by dbarton62

Wow that is serious
You must have some very worn out bushings in the rear to get enough movement to fatigue that much.
IMO you need to replace the subframe. Don't know if you could repair that and get correct alignment for the bushing.

Edit, looking at the mess of that bushing I am not surprised the metal fatigued

The bushing wasn't like that when I was under the car doing a massive overhaul about a month back. Shortly after completing everything I started getting a slight thud noise on hard acceleration. I just thought it was a gear backlash issue because i switched to the UUC lightweight kit and it would not be as forgiving of slop in the drivetrain as the DMF. I had been suspicious for awhile that the diff wasn't as tight as it should be for awhile before I did all the recent work but I didn't think it was bad enough to be an immediate issue. I decided just to baby her a bit until I could get the time to get into it. Well about a week ago the thud got exponentially worse over a short period of time telling me there was a more serious issue.

The front bushings are fine, this bushing was fine until the mount failure. I can pinpoint when it failed now that I think about it. when I was benching the trans back into place there was a real loud POP from the rear end that just about made me shit myself thinking I was about to have the car come down on me. I took the trans back out, couldn't find any issues, did a cursory look around the car and couldn't figure out what it was. Since I wasn't messing around in the rear then I didn't think to check it.

Well, about a year ago I had the same exact thing happen to my sway bar bushing mount. It just popped in half, same noise, about the same guage of steel, just let go. dunno why. I take care of the car and make sure all the rubber bits are good as a preventative chassis maintenance program. This is, I think, a new way for the subframe to fail. I don't think I've ever seen anything like this talked about.

Really don't have the free money to drop on a subframe after spending several thousand on her already.

[Steeler]

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