OK, let me get this straight. If you pull the brake caliper off, the track turns fine, right? This will prove that it is the brakes and nothing else. If that is so, then the after market pads are too thick or the caliper piston is sticking.
If it was just a fluke and you still have problems with the track locking up check you rear shock mount and make sure it is up and not down, they always tip down when you put the skid in and you need them up.