Alignment shims are used on straight axle, leaf sprung applications to adjust castor when aligning the vehicle. They may be referred to as wedges or castor wedges due to their shape and their purpose. These alignment shims will be placed under the leaf spring packs to tilt the axle in the needed direction and degree. When ordering wedges, choosing the correct degree and spring width is important as well as the type of shim. Zinc is used for up to 12,000 lb. axles without spacer blocks while bronze and steel