The 4-1/2″ King Pin Bolts are used on our EC Front Axles and many others to hold the spindles to the front axles. 

The kingpin allows the spindles to pivot, and by using heims or caster blocks, you can change its inclination to make camber and caster adjustments.

The kingpin also has its own built-in inclination when the front axle and chassis are made. Kingpin inclination or KPL is important for the handling dynamics of your chassis; if you are unsure of the geometry for building your own axles, we recommend using our fully adjustable front axles for racing lawnmowers.