Sounds like I may have similar issues with my 2007 Alpenlite brakes. Also self adjusting. I am one for doing touch checks at rest stops & any stops when driving the mountains. Rear axel drums, both sides, get warmer from braking. Bearing temps similar all round during extended highway running.
Planning to replace whole plates, magnets & shoes all round though I suspect front ones will be perfectly good. Will clean them up & keep as spares. Will also get a couple spare bearings.
Planning another Alaska trip & it is nice to at least have vital spares onboard eliminating a potential shipping wait or absurd amount for express shipping up there.
