The pic below is what a ballpin in a bottom balljoint looks like after sliding on a metalled road for approx 15 metres with the initial speed at the time of contact between the pin and the ground being approx 60kph - this accidentaly occurs when one's automobile looses its front passenger side wheel at the said 60kph. Mental picture a front wheel suspended 2 metres in the air just above your front guard and a warm funny feeling fills your pants.
The said wheel then proceeds to fly across a 3 lane major road and hits the curb and bounces back - bounces quite interestingly right back into ones car - just as one finishes landing the 3 wheel vehicle by the side of the road and ironicaly congradulates one self for negotiating the said 3 lane road safely and not killing anyone - as the wheel hits the car it smashes the left hand side mirror and lands nicely next to the car without inflicting any other damage and most importantly without killing or atleast knocking anyone out.
NOW this ball pin is usualy twice as long and has a threaded end that passes through the bottom arm and is secured by a large nut and a spring washer -after the concrete glide the nut was nowhere to be found and the pin was flush with the arm (the RED section in the pic is the missing part). So remember kids - idealy your wheels should stay on the car.
