Mike,

I've never worked on the "Modern" brake systems.  Only the '85 and older
with 2 pistons.

On my '85 Westy, the inboard piston on the driver's side froze up and
wasn't moving.  The outboard pad wore much faster and was pushing the
rotor over against the frozen pad and was wearing it only a little.
Strange that there was no pulling or other indication that something was
amiss.  Rather than trying to rebuild that caliper, I just replaced it.

My best guess is that your caliper isn't working properly internally and
isn't pushing one pad as hard against the rotor as the other.

Mike

mwmiller@cwnet.com wrote:
 > 87 syncro