Strut mount and sealing ring

[DWBOX2000]

There is a faint banging around noise is my right rear quarter when driving. Do strut mounts usually go out in pairs or can one last considerably longer? My left side is good. I just check the torque, all are ok. I jacked car up and shook everything around, no noise. I then put a 2x4 under tire and bounced up and down, noise appeared. Left side doesn't do. Would having a bad sealing ring be likely another possible cause. I noticed it was in rough shape when I had struts off a year or so ago. I replaced the left side. I know, dumb move not replacing when I had the chance.

[DWBOX2000]

The ring is the rubber elastic that goes around edge of mount.

[That986]

Originally Posted by DWBOX2000

There is a faint banging around noise is my right rear quarter when driving. Do strut mounts usually go out in pairs or can one last considerably longer? My left side is good. I just check the torque, all are ok. I jacked car up and shook everything around, no noise. I then put a 2x4 under tire and bounced up and down, noise appeared. Left side doesn't do. Would having a bad sealing ring be likely another possible cause. I noticed it was in rough shape when I had struts off a year or so ago. I replaced the left side. I know, dumb move not replacing when I had the chance.

You only replaced one shock, not the pair? Bet that feels good at the back.

Are you sure it's not your track control arms, they knock around.

[DWBOX2000]

No, sorry. I replaced the springs on both sides. Bilstein HD's were not changed. It was the rubber ring that goes around the edge of the strut mount where it creates a cushion between the mount and body. I only replaced left side. Dumb I know. It looked a bit rough.
Can I tighten the strut mount with the strut disconnect from the body but still in the wheel well? I had a tough time since I couldn't use my torque wrench since I had to put an Allen wrench (or something similar) on the strut shaft to keep from turning. So maybe it just needs to be tightened a bit.
Sorry, mechanics is not my first language.