Steering King Pin Shim

What Is a Steering King Pin Shim?

Deep within your front suspension sits one of the most mechanically critical components in your vehicle's steering system: the king pin. The king pin is the primary pivot point that connects the steering knuckle to the axle beam, enabling the front wheels to turn left and right under driver input while simultaneously bearing a significant share of the vehicle's load. Keeping this pivot operating within tight tolerances is essential — and that's exactly where the steering king pin shim comes in.

A steering king pin shim is a thin, precisely dimensioned spacer used to set and maintain the correct clearance between the king pin and its surrounding bushings. Over time, king pin bushings and pivot surfaces wear, allowing unwanted play to develop in the steering assembly. This looseness can manifest as vague or wandering steering, accelerated tire wear, and degraded handling stability — symptoms that become especially problematic on trucks, heavy-duty vehicles, and older cars that rely on solid front axle designs. Installing correctly sized shims during a king pin rebuild restores the factory-specified fit, eliminating slop and returning the steering geometry to spec.

Why King Pin Shims Matter for Steering Precision

Shims may look like simple washers, but their role in suspension setup is anything but trivial. Proper shim selection ensures the king pin sits at the correct depth and preload within the axle knuckle, directly influencing steering feel, caster geometry, and the self-centering behavior of the front wheels. Incorrect clearances — even a few thousandths of an inch off — can introduce excessive play or binding, both of which compromise vehicle safety and component longevity.

When performing a king pin service, technicians measure the existing end play and lateral clearance with a dial indicator, then select shims of the appropriate thickness to bring those measurements back within the manufacturer's specification. King pin shims are typically available in a range of thicknesses, allowing for fine-tuned adjustment across different wear conditions and vehicle applications.

What to Look for When Shopping King Pin Shims

• Thickness: Match the shim thickness to your measured clearance gap. Common thicknesses range from 0.005" to 0.030" or more.
• Outer Diameter: Shims must seat correctly within the king pin bore; verify the O.D. matches your axle specification.
• Material: Quality shims are made from durable steel to resist compression and deformation under load.
• Application Fit: Always cross-reference by year, make, model, and axle type to ensure a proper OE-style fit.
• Pack Quantity: Shims are often sold in multi-packs, which is practical when servicing both sides of an axle or performing fleet maintenance.

Top Brands in Steering King Pin Shims

When it comes to sourcing reliable king pin shims, brand reputation matters. Moog Chassis Parts is one of the most trusted names in the business — widely recognized as the chassis industry's "Problem Solver" for its commitment to design enhancements that extend part life and simplify installation. Moog's king pin replacement components, including shims, are quality-tested and engineered for durability in both street and off-road applications, making them a go-to choice for professional technicians and serious DIYers alike.