[Racer20]

I'm not looking forward to the thought of swapping all the MPHAS hardware to a new strut and dealing with that whole mess just to put a new $1000 strut on the car and have it still clunk. So, I figured I'd do some more easy testing before I really dig in.

I got all new sway bar hardware (links, body bushings, and new nuts) so I removed all the underbody protection and pulled the bar off. Figured this was a good chance to see for sure if the bar was the source of the noise or at least a transfer path, so off to my test bump I went armed with my chassis ears.

Things I learned:

1. The sway bar or end links aren't causing the clunk.
The noise is still there, even with the bar and end links completely removed. It's maybe a bit worse than before since the suspension can now articulate more.

2. Chassis ears are a little bit fiddly.
I moved the mic that I had on the coil spring to down a coil to avoid contact with the body. The mic must have been hitting something else last time, because there it's silent now. I clipped a mic on the pass. side spring to compare, and they sound the same. No noise. Sometimes it's tough to tell if the noise is actual noise or just the mic clip being jostled around.

3. The damper itself is pretty quiet too.
I clipped a mic onto the "nub" that's formed into the bottom cap of the damper, assuming that anything that's transferred through the strut body will light that up. Nope, quiet as a mouse.

4. The tension arm is NOT quiet.
I tried a few different mic placements on the tension arm (one example shown in the pic), and this seems like the most likely transfer path at the moment. The loudest is when I clip it to the extra threads at the bottom of the ball joint. Next is the bolt on the other end, and it can be heard faintly from the subframe just next to the tension arm bolt. Out of the 5 different mic configurations I tried, I could hear the noise through the tension arm in 4 of them.


Conclusion:

Ordered a new tension arm. I have to take it off anyway to replace the strut in order to fit the puller tool in there per BMW's instructions.

My strut sill has lag, so I might replace it regardless, but I want to see how it sounds/rides after the tension arm replacement. I'd rather not do all that work for minimal benefit.