Thunk in my E36.

Hey all, need a little wisdom here. My E36 makes a noise that can best be described as a pop or a thunk that occurs when changing direction under load. For example, it happens most often when I disengage the clutch in reverse on a hill or under high load. There is a slight delay between power transfer and the noise. It will happen again when I go back into first. Its been happening for a while now and I have not been able to pinpoint the problem. I suspected a CV joint so I replaced a leaking axle. It seemed to fix the noise for a while but now its back. Now the outer CV joint on the other side has some play as well. I swapped to another axle which seemed to quite the noise but then it came back again. The car is properly aligned and both rear wheel bearings are good. All bushings are good (subframe bushings are the only questionable ones.) Speaking of subframes, I dont see any cracks or breaks in the sheet metal of the body. Guibo is good too. The front diff bushing is a little worn but I dont see how it could be making such a noise. I suspect the drive shaft bearing could be it but I have no idea how to diagnose such a thing. I put a bore scope in there the other day but couldnt see anything that looked off. Im not getting any weird vibrations either. Any thoughts on where I should start? I would rather not throw parts at it.

subframe bushings can and will cause that noise as it moves when getting on and off of the power.

Have you checked the joints on the driveshaft itself? This includes the rubber donut or "guibo" at the back end of the transmission

My Ti had a bad driveshaft joint that produced the same symptoms

Front diff to subframe bushing bolt. See if it's bent. If so, replace the bushing and the bolt together.

I've been down this road all the way, to the point of milling the face of the diff the bushing mates on and putting in a threaded insert to fix the less-than-perfect threads.

New bolt w/ Loctite and book torque value.

Forgot to mention, Guibo looks good. Diff bolt was replaced a while ago with an upgraded unit and was installed with loctite and a healthy dose of torque. The noise doesnt happen when coming on or going off power, only when changing direction. Drive shaft joint? Is that the center support bearing? I stuck my bore scope into the tunnel but I didnt really know what to look for. Nothing looked obviously bad but the car has 211k miles and to my knowledge the bearing is original.

I vote subframe bushings as well.

when going from reverse to forwards or vice versa? That sounds like subframe bushings. You are literally torqueing the whole assembly one way then the other when you change direction like that

Also check the upper shock mounts. They'll make some pretty bad thunks and clunks when they're shot.

mine did this and it was the rear subframe mounts were torn out. with the car up you could see the tears without moving anything.

Hope thats not the case for you.

Shock mounts are Turners repair shop mounts.

Ill have to check the mounts again a little more carefully. Is there a way to check the bushings without dropping the subframe? This is my daily and I cant have it down for long, especially just to check something.

Check the rear suspension adjustable camber bolts. I had one loosen up and seize itself into the bushing. It took a trip to the $60 alignment shop to finally find it.

the hardest part of replacing the shock mounts.. getting to them from inside the car. once you can access them, it is a half hour job. Two bolts hold them to the car and one for the shock

Sorry, that was misleading. The shock mounts are solid so there is nothing to go wrong there. I meant the subframe. Is there a way to check the bushings without having to drop the whole rear end?