From cuts to custom fender wells on my Mustang - FINAL
This video shows the final stages of converting trimmed fenders into finished custom fender wells on a Mustang to accommodate wider wheels and tires. The build covers cutting the factory metal, fabricating and shaping new wheelwell panels from sheet metal, welding them in, sealing and priming, and finishing so the wells are strong, sealed from the elements, and ready for paint and liners.
Build Sequence
1. Measure clearance and mock up layout
With the wheel and tire installed, measure the clearance envelope and mark where the factory inner fender needs to be altered. Mock up the shape of the new wheelwell using cardboard or template material to confirm geometry before cutting metal.
2. Cut the factory metal
Using an angle grinder or cutoff wheel and a spot-weld cutter where needed, remove the factory lip and any obstructing sections of the inner fender. Keep cuts controlled and leave room for flanges to weld to.
3. Create templates and trace panels
Transfer the cardboard templates to 18-gauge sheet metal and cut the rough shapes. Mark bend lines and areas that will need hammer/dolly shaping or flange formation.
4. Shape and fit the new wheelwell panels
Use a hammer and dolly, shrinker/expander or small bead roller to form the sheet metal to match the factory contours. Test fit repeatedly, trimming and shaping until panels sit flush with existing structure.
5. Weld panels into place
Clamp the panels and weld using short tacks or plug welds to avoid warping. Use weld-through primer on seams before welding, then finish welds and grind smooth as needed.
6. Seal and treat seams
Apply seam sealer over welded seams and any joints to prevent moisture ingress. Spot-prime weld zones with epoxy primer or rust inhibitor.
7. Body-finish and prep for paint
Featherfill low spots with body filler, sand smooth, then apply epoxy primer to the fabricated areas. Block and guide to ensure a smooth transition between new metal and factory surfaces.
8. Install liners and final hardware
Trim or fabricate plastic liners and attach with pop-rivets or fasteners. Re-check wheel/tire clearance and reinstall any removed suspension or splash components.
Frequently Asked Questions
How much wheel/tire clearance should I leave when shaping the fender well?
Leave at least 10–12 mm (around 3/8" to 1/2") of static clearance between the tire and the inner lip with suspension at full droop; more is safer if you expect suspension travel or aggressive steering/alignment changes.
VIEW FULL ARTICLE →How long does a project like this typically take?
For someone with metalworking and welding experience, expect a full weekend (12–20 hours) from measurement through fitting, welding, and sealing. Novices will take longer, especially during shaping and finishing.
VIEW FULL ARTICLE →Do I need any special tools to make custom fender wells?
Basic fabrication tools (angle grinder, drill, MIG welder, hammer/dolly) are required. Access to a sheet metal brake, shrinker/expander or bead roller helps achieve factory-like contours but isn't strictly mandatory for simpler shapes.
VIEW FULL ARTICLE →Do I have to weld the new wheelwell panels, or can I bolt or rivet them?
Welding is preferred for strength and to restore structural integrity, but panels can be riveted or bonded in place if welding isn't an option. If you rivet or bond, be sure to seal seams thoroughly to prevent rust.
VIEW FULL ARTICLE →Will cutting and welding the inner fender cause rust problems?
Not if you properly treat and seal the new metal. Use weld-through primer during welding, then apply epoxy primer, seam sealer, and paint. Ensuring proper sealing and coating is key to preventing future corrosion.
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From cuts to custom fender wells on my Mustang part 3Parts Used (8)
Material to recreate or line the inner wheelwell for splash protection.
Grinding, shaping and cutting metal during fabrication.