What are shims? Why buy them?
Shims are thin metal wedges that have been machined to a specific thickness in order to change suspension and wheel geometry for alignment purposes. By adding or reducing the amount of shims it is possible to change camber and castor angles which can have a dramatic effect on vehicle handling and control. Any time you alter your vehicle’s suspension or add new wheels and tires it is important to check and adjust the alignment on a modern alignment machine. For many vehicles, the only way to get the alignment into spec is with the addition of shims. However, adding and removing shims is a very precise job and should be left to a professionally trained alignment specialist. If you are trying to guess how many shims to add you could wind up hurting your vehicle’s performance more than helping it.