Quarter Panel

Quarter panels are the rear side panels of your Mustang's body. They're called "quarter" panels because each one covers roughly a quarter of the car's exterior—left rear and right rear.

On a Mustang, the quarter panel extends from just behind the door all the way to the rear bumper, wrapping from the rocker panel up to the roof rail (on coupes) or to the convertible deck (on ragtops). It includes the wheel arch, the character lines that define the body shape, and the mounting points for taillights and trim.

Unlike bolt-on parts like doors or hoods, quarter panels are welded to the car's structure. Replacing them is major surgery—you're cutting out the old panel and welding in a new one, which requires skilled metal fabrication and precise bodywork.

Here's why quarter panels matter: they rust. The lower sections trap water, road salt, and dirt. The wheel arches get sandblasted by road debris. Previous owners bondo over the rust instead of fixing it properly, and 40 years later you're looking at replacement.

I watched a shop cut out a quarter panel that looked fine under the paint. Once they ground off the bondo and filler, the lower 8 inches was Swiss cheese. The replacement panel cost $600. The labor to install it properly cost $4,500.

Quarter panel condition is a major cost factor in any restoration:

Common issues:

• Lower rust - Road salt and water collect at the bottom edge
• Wheel arch rust - Rock damage and moisture lead to perforation
• Collision damage - Rear-end hits crumple quarter panels
• Previous "repairs" - Bondo over rust that's now failing
• Poor reproductions - Some aftermarket panels don't fit correctly

Replacement scenarios:

• Patch repair - Small rust section cut out, patch panel welded in ($800–$2,000)
• Lower quarter replacement - Bottom 12" section replaced ($1,500–$3,500)
• Full quarter replacement - Entire panel replaced ($3,000–$7,000 per side)

The decision to repair vs. replace depends on how much of the panel is compromised. If rust or damage covers more than 30% of the panel, replacement is usually more cost-effective than extensive patchwork.

Quarter Panel Replacement Process:

1. Strip trim & glass - Remove taillights, emblems, side glass, weatherstripping
2. Assess extent - Determine how much of the panel needs replacement
3. Cut out old panel - Carefully cut along factory seams without damaging structure
4. Inspect inner structure - Check for rust in inner wheelhouse, frame rails
5. Fit new panel - Trial-fit reproduction panel, mark and trim for alignment
6. Weld in new panel - Stitch-weld new panel to body, avoid warping from heat
7. Body filler & shaping - Fill low spots, shape panel to match factory contours
8. Block sanding - Hours of sanding to achieve smooth, straight surface
9. Prime & prep - Apply primer, final sanding, prep for paint
10. Paint & reassemble - Paint panel, blend into adjacent panels, reinstall trim

This is 30–60 hours of skilled labor. Shortcuts here show in the final finish.

Reproduction Panel Quality:

OEM-Style Panels (Best):

• Dynacorn, Goodmark, Auto Metal Direct
• Correct contours and body lines
• Fit well with minimal adjustment
• $400–$800 per panel

Budget Panels (Acceptable for driver quality):

• Generic imports
• May require more fitting and adjustment
• Thinner gauge metal in some cases
• $200–$400 per panel

NOS (New Old Stock) Ford Panels (Rare):

• Factory original panels from 1960s–1970s stock
• Perfect fit and finish
• $1,500–$3,000+ when available
• Only worth it for high-value concours builds

For driver-quality builds, OEM-style reproductions are fine. Save NOS panels for rare Mustangs where originality justifies the cost.

When to Repair vs. Replace:

Repair with patch panel if:

• Rust is isolated to lower 6–12 inches
• Damage is localized (small dent, limited rust)
• Rest of panel is solid
• Budget is tight

Replace full panel if:

• Rust covers more than 30% of panel
• Multiple areas of damage/rust
• Previous repairs are failing
• Doing show-quality restoration
• Panel is creased or buckled from collision

The labor cost to patch extensive rust approaches the cost of full replacement. At a certain point, replacement is cleaner and more cost-effective.