Whenever I park on a hill or say my house's 30% grade driveway, I notice that after starting the engine and shifting into rear gear, there is an unusually strong kick coming from the transmission. It only recently occurred to me that it must be because all of the stress resulting from holding the parked car still is from transmission instead of the hand brake. To test this theory, I stopped my car in our driveway, shifted into neutral, activated the "hand brake" and released the normal brake. The car rolled back and would keep on going unless I apply normal brake. Is this normal? I thought that the hand brake should be strong enough to keep the car still.