Dan the Gear Man Tech® Note 1:
Shims are used between the King Pin Caps and Steering Knuckles to set your Knuckle Bearing/Bushing turning preload. More shims decreases preload, less shims increases preload. King Pin Caps are shimmed to put the specified turning preload on the bearings. The amount of turning preload varies by vehicle and year but the value is measured by a beam or dial type torque wrench (refer to the vehicle manufacturer Service Manual for your specific model specification). Too loose can cause poor steering or "Death Wobble", too tight will lead to rapid bearing failure, broken parts, and possible steering loss.

Dan the Gear Man Tech® Note 2:
Chevy, Dodge, GMC, IHC, and Jeep also used Dana 12 bolt closed knuckle axles. These axles, which originally used the out of production QU40327 Bronze Upper King Pin Bushing instead of QU50600 Bearing can use this Kit if the Knuckle turning preload is set at 9-15 Lb. Ft. (12-20 Nm) without QU40189 Ball Seal or steering rods Installed on Knuckle. Also See QK4616 for our King Pin Bushing and Bearing Kit.

Dan the Gear Man Tech® Note 3:
If you have a Dana 25, Dana 27, Dana 30, or Dana 44 front axle with 8 bolt ball seals, see QK4617.