Check the brackets holding the bag mounting rails. I know of 2 FLHRS owners who had the left one break. I've included a picture. its not a custom, but it will give you the idea.

its the brackets with the 2 big allen head screws between the bags and the rear fender support near the mufflers. There are actually 3 brackets connected at that point on each side, the one that breaks is the one that is farthes outboard, and IIRC, I think it has the muffler connection.

It makes a big racket when broken.

Tim

 

Same problems. Humming turned out to be tires... just the tread cut bit I agree it does sound like an axle bearing. The front clang? Nothing has fallen off and just came back from 1,500 trip with Mrs. but the noise always concerns me. The rear noise at idle just showed up and at first I though I lost a main bearing. Scared the s**t out of me. Then I realized it was from the back left side and not the motor. Whew!

I guess it is just the pleasure of owning American Iron. Gotta love it... I do.

 

I've had a whine or groan apparently from the rear and most notably on the left side. It started soon after installing an E3 on the rear, got worse after a few months, but hasn't gotten worse since that time. It lessens on hard left turns, increases on hard right, is mostly apparent between 25-50mph and is speed-related. Belt tension is a looser than spec now (9/16" cold using the 10# method), but adjusting tighter does not change the noise.

I tried jacking the bike up and putting my ear closer to the problem, but the result was inconclusive. I've learned to live with it since it hasn't gotten worse in over a year, but I'm going to try the silicone-grease-on-the-belt-edge trick tomorrow. The E3 is a stellar performer and if I must endure some whine so be it, as it is that good.

It just doesn't sound like a bearing, so I've ruled that out, and a trusted tech at the dealer thought it was the belt and suggested that I spray some dry silicone or Teflon lube on it, but that didn't change anything.

 

I've got the chrome filler strips so I can't see the mounting hardware. I guess I'll have to take em off.

The noise seems only to happen at idle; when vibration is at its worst and it always comes from the right side, rear. I'm fairly certain it has something to do with the muffler, the muffler bracket or the bag mounts but finding it has been elusive.