I hadnt on my car for very long when I stepped on the brakes and my passenger seat flew clear up to the dash. When I stopped and looked at it, they were little metal teeth all over the place underneath the seat. It wont go all the way up and lock it will only go all the way back and semi lock. If theres someone sitting in the passenger seat when I press on the brakes, it moves up a few inches and then back it will not lock completely