If the rear wheels lock up too soon, the vehicle becomes unstable especially during a hard stop - the rear of the vehicle pulls to one side and the vehicle begin to skid. The causes: possibly the wrong brake pads or shoes fitted to the front or rear of the vehicle, a wrongly-adjusted or faulty brake proportioning valve, oily or worn-out front brake pads, worn-out or damaged front brake discs, defective front brake calipers. Immediately take your vehicle to a specialist workshop or ATE BrakeCenter to find the cause of the problem. And use Original ATE brake parts to repair the fault.