Buy auto body fender shims
Choosing auto body fender shims is less about picking a universal part and more about matching the shim to the substrate material, the repair method, and the final panel alignment you need. A fender that sits proud, tucks inward, or shows an uneven gap after replacement or collision work often needs a controlled spacer rather than more force on the mounting bolts. The right shim restores the designed relationship between the fender, hood, and door edge while leaving room for corrosion protection. Commercial kits and individual shims vary by thickness, material, and shape, so the direct answer below explains what to check before you buy.
The direct answer
Buy auto body fender shims only after you know the gap or offset you are correcting and the fastener size that passes through the shim. A shim that is too thick can force the fender outward and disturb the hood-to-fender margin, while one that is too thin may not hold the adjusted position. Basic slotted shims slip behind the fender mounting flange and allow incremental spacing without fully removing the panel. For most repairs, a mixed-thickness set gives more control than one fixed size, but the shim must fit the bolt or clip diameter and remain narrow enough to stay hidden behind the flange.
Material and corrosion protection matter as much as thickness. Steel shims provide firm support for a bolted fender, but they should be coated or placed against a clean, primed surface so trapped moisture does not accelerate rust where the shim meets the substrate material. Plastic or composite shims avoid direct metal-to-metal contact and can be easier to trim, yet they may compress differently when the fender bolts are torqued. Regardless of material, clean surface preparation and a compatible coating help the adjustment last after the panel is aligned.
