Remo Weatherking Standard Hazy Timpani Heads Determining size The size of your timpani head is determined by the diameter of the bowl itself. Measure the old head from the outer edges if this measurement exceeds the bowl size by more than 1-3/4 inches you need an extended collar head. If you are not sure of which size to get call us and well help out.Be careful when removing old timpani heads Pedal type timpani tuning mechanisms are spring loaded. The pedal will move to the toe down forward position - do not try to hold it back. Also do not adjust the balancing spring tension. When replacing head the opposite reaction will take place. It is recommended to use a small dab of Vaseline Petroleum Jelly on the threads of the key rods for lubrication. Be sure to clean the bearing edge of the bowl. It should be smooth to the touch. If possible apply a very thin film of paraffin wax to the bearing edge before replacing heads.