[gogo911]

I upgraded my front Carrera calipers on my 88 911 n.a. to early Boxster calipers. I've now run two sets of pads through it. Currently running Hawk Blues. I am running into a problem of pad friction--as in the pads are not retracting sufficiently upon pedal release which is causing undue friction. The dust seals on the pistons appear fine, brake fluid (ATE Gold) flush was just done, and once the pads are pushed back, the wheel turns freely. Bearings are adjusted properly and yet I still get pad rub.

I wonder why the pads are not retracting enough? One theory I have... could it be due to a warn master cylinder maybe which doesn't have enough back pressure? Is the master cylinder just not strong enough compared to the Boxster's? Any viable solutions exist?