You say the frotn wheel rotates 3 times with the left caliper off and right in place . 1.5 times with both in place . Have you removed the right caliper to see about the rotation with only the left caliper in place ?
The left caliper , connected to the rear system is used frequently and therefore might not be as relaxed as the right caliper . Do you use the front brake often ? Try stopping with the front and rear brakes together so that both calipers are recently used . Then check how free the wheel rolls with both calipers inplace or either in place. I am suprised the rear wheel spins freely . Disc brakes do drag . The have no retacting mechanism other than the seal/dust boot . That wont move a piston far .
The left caliper , connected to the rear system is used frequently and therefore might not be as relaxed as the right caliper . Do you use the front brake often ? Try stopping with the front and rear brakes together so that both calipers are recently used . Then check how free the wheel rolls with both calipers inplace or either in place. I am suprised the rear wheel spins freely . Disc brakes do drag . The have no retacting mechanism other than the seal/dust boot . That wont move a piston far .
