...well maybe you can help me? I have a KMC Z510 HX chain, which is fine links/length-wise...until it stretches. Once it stretches the wheel has to come out in the dropout a couple of mm and the pads no longer make full contact with all the rotor (brakes are Shimano Deore M595). The caliper will not move any further along its dropout fixing as the rear caliper bolt hits the frame. Removing a link makes Mr Chain too short.
Any hoo, my question is...what chain are you running? Especially if you're using the same calipers.