I've got a 92 vert with a brake issue the rear brakes won't completely stop the rear wheels. It's got a 5 lug 4 wheel disc conversion with an adjustable prop valve for the rears. 95 spindles with 99 dual piston calipers , 95 booster and master cylinder and 95 single piston calipers. I jacked the rear end of the car up with it in drive with foot on brake and notice the rear wheels turning. The rears bleed fine. Any thoughts ?????