King pins and bushings are vital steering system parts on large trucks. Regular maintenance and inspection is recommended to ensure safety of the vehicle. If replacement is required, some king pin bushing models require special tools. Tools commonly used for king pin bushing removal and replacement include a press, soft brass drift punch, and a reamer.
A hydraulic press is often used in the removal of a king pin bushing due to the extreme difficulty that can be experienced while attempting to remove the king pin. Removal of the king pin without one is nearly impossible in large trucks like semis and buses. Using a press eliminates the need for sledgehammers and torches, and the hydraulic pressure removes the king pin with little effort. Press tool kits are also available for king pin bushings. Press tool kits are used by inserting the compression nut into a ratchet.
Soft Brass Drift Punch
A soft brass drift punch can be used in place of a hydraulic press to remove the king pin bushing. Generally, it is recommended that an air hammer be used when removing a king pin bushing with a soft brass drift punch, which will make the removal of the king pin easier. The use of a sledgehammer or traditional hammer can take a lot of strength and effort, especially on a large truck. Soft brass drift punches are the best alternative to a hydraulic press because they will not spark or damage other metal parts.
Reamers are not used in the replacement of all king pin bushings. Half-ton and three-quarter-ton trucks use what is called a "floating" bushing, recognisable by their bronze colour. Floating bushings do not require reaming because they are manufactured to the final size. One-and-one-half-ton trucks do require the bushings to be reamed, because the bushings are press-fit into the spindle. For these types of king pin bushings, a reamer is required. When reaming is required, it is important to avoid honing or burnishing the king pin bushings, which will cause damage to the bushings. Reaming is done with the use of an adjustable straight flute reamer to ensure that no parts are damaged. To use the reamer, it is inserted into the steering knuckle just until the blades touch the bushing. It is then rotated with a slight downward pressure. Applying too much press can also cause damage to the king pin. Driving with a damaged king pin is extremely dangerous, and can cause a loss of control to the vehicle, possibly resulting in an accident.