A sprocket unit comprising: a damper mounted on the first shaft with a first face defining a recess and a second face defining chambers for receiving spring loaded weights; a sprocket mounted to the first shaft with a hub defining an aperture and a slot; a front end plate mounted on the shaft with a hub defining an aperture aligned with the aperture of the sprocket; and a spring received within the aperture of the sprocket, the aperture of the front end plate, and the recess of the damper. When the first shaft rotates and firing frequency of the engine coincides with a resonant frequency of the first shaft, the spring loaded weights slide in the chambers of the damper, dampening out the resonant frequency in the first shaft and when the sprocket rotates the spring compresses and extends, reducing torsional load of the first shaft on the second shaft.