I have 4 piston fixed calipers on the rear of my 72 and have been working on minimizing possible brake pad bump back and trying to cut down on brake drag. I did some modification to my axles and have them at .004 to.009 end play, so I don't think the bump back will be an issue anymore. What I need is some input on is the caliper side to side tolerance on the disc. I have ordered the shim washers that will get the caliper perfectly centered on the disc but I wonder how much difference it will make on brake drag or pedal feel. Right now both of the calipers are off center to the outside by .078 on one side and .115 on the other. The only thing that centering them will do is make the caliper pistons at the same depth on both sides of the caliper. Does it make any difference if they aren't even?