Identify this noise?

[Andy JB]

A long-shot perhaps, having owned my 500 for 14 years i'm pretty familiar with all its foibles, noises and maintain a most of it myself.

Recently its developed a knocking noise which sounds like its coming from the rear, i wondered if anyone else has had this issue and point to anything obvious i've not considered?

Its best described as a rotational noise like perhaps a brake caliper catching on the disc, particularly at speeds below 50mph. I've stripped rear down checking & tightening everything up from dampers to arms to fuel pump, exhaust & nothing is loose or broken. Nothing reported on MOT & local Indy couldn't find anything wrong or safety critical. Its driving me insane to the point i don't want to drive it.

I was thinking perhaps track rods, differential, but what do these sounds like if they wear out? If anyone has any ideas i'm all ears.

[rgw2012]

Shot in the dark - only because you haven't mentioned it but have probably looked - wheel bearing?

[Andy JB]

Thanks worth considering although it doesn't sound like a traditional wheel bearing type noise, not sure how i would check that though

[N7GTX]

Jack the rear of the car up and place on axle stands. Start the engine, let it warm up for a couple of minutes till idle is settled, put it into 3rd gear and let the clutch out slowly. Wheels will now spin and you may hear a wheel bearing rumble. You may also hear the diff making bearing noises - place a long big screwdriver tip against the diff and the handle hard against your ear - and maybe CV joints knocking. You can place the tip of the screwdriver against the hubs to listen to the bearings and compare each side.
The only problem if it is a wheel bearing is that the weight of the car is not loading the bearing so it could still be worn even if it runs quietly.
Check the propshaft UJs by gripping the propshaft and trying to turn the flange part back and forward. Remember to check both ends!