Why is my rear-end making these noises? (And getting worse)

[ArtFoodBMW]

So the first problem,

Since I purchased my 85 325e, when I let off the gas going slow in a lower gear (ex. 30mph in 4th gear) I get a weird shake from the back end. It reminds me of when I didn't know how to drive stick, and i was letting the clutch out too fast without enough gas. A back and forth motion and it's relatively loud.

I replaced the CSB, guibo, and differential mount. Still does it a year later. This problem is depicted in the third section of the video posted below.

2nd problem.

Much louder and violent than the first problem. It just started a week or so ago. When I'm stopped, and then step on it quickly in first gear, the rear felt like it was being hit a bunch to move forward but there is no loss of power. This was occasional but now everytime I step on the gas in first, lightly or not, it feels like a machine gun is going off in the back.

It's starting to do it on a rolling start in 2nd gear now as well.

The second problem is depicted in the first two parts of the video below. It's also much louder than the video leads it to be.

Looking at the video, It looks like my seat is loose, and I can assure you it's not, that's just how violent the shaking is.



I have no idea if these problems are related or not, but if you have any idea whats causing them please let me know.

I got under the car today to see if it was something visible like a cracked subframe or leaking differential but I saw no signs of that. I was thinking it could be the subframe bushings, but those don't seem to be completely busted/ I can't really tell.

TIA

HELP ME

[efficient]

Are your subframe bushings the original ones or have you ever replaced the bushings?

[ArtFoodBMW]

Original bushings, 190k miles on the clock

[Stanley Rockafella]

boom! there's you problem
rear subframe bushings. Replace them and your car will be tighter than you've ever imagined.

Also, your gonna need an alignment after they are replaced

[efficient]

Not necessarily true^.
If he doesn't have rear adjustable alignment then you can't align anything.

[ArtFoodBMW]

Any recommendations on subframe bushings? I don't want to put stock bushings in, but I also don't want a rock solid rear end

[e30 gangsta]

condor 12mm risers.

[Stanley Rockafella]

Not necessarily true^.
If he doesn't have rear adjustable alignment then you can't align anything.

no, you fail to understand that the car has probably had alignments (in the front of the car) since it was new with new rear bushings. As the bushings fail, it changes the geometry of the suspension, requiring the front to be re-aligned.

So when he finally gets new rears in (so the geometry will change again) it'll set off the front alignment again...requiring another alignment

[DRTSRFR]

Hmmm...

I see what you are trying to say, but small changes in rear rake will only affect caster up front, and that's not adjustable without plates.

Now, If it was a big change in rear ride height, the front would lift slightly as well, which will effect toe.