Restoring Crunchy Fenders: A Guide to Repairing Bacon Panels

Nothing mars the sleek lines of a classic car like a set of wavy, rippled rear fenders. This warping of rear quarter panels is commonly known as “bacon fenders” due to their resemblance to rashers of fried bacon. While cars with bacon fenders might look tasty to some, most auto enthusiasts want straight, flat rear fenders. Read on for a step-by-step guide to diagnosing, repairing and preventing those pesky bacon fenders.

What Causes Bacon Fenders?

Bacon fender distortion generally occurs over time as a result of

• Metal fatigue – Fenders loosen and weaken from decades of vibration, stress and exposure to the elements.

• Rear collision damage – Even minor bumps or scrapes to the rear can ripple the thin metal fender panels

• Improper repairs – Shoddy bodywork or fender replacements use improper techniques or materials, resulting in eventual warping.

• Lowered suspension – Lowering or altering the suspension puts more stress on fender panels not designed for that geometry.

• Moisture damage – Rain, snow and road salt accelerate rust and corrosion compromising panel integrity.

Unfortunately, once fenders start rippling, the distortion has a tendency to gradually spread across the panel over time unless addressed.

Assessing Bacon Fender Damage

Step one is to thoroughly assess the scope of the fender damage:

• Look for visible rippling – Scan the entire fender area on both sides for any visible waviness, peaks and valleys in the sheet metal.

• Run a hand across the surface – Often wrinkles and distortion can be felt before being seen. Feel for any irregularities.

• Use a body hammer – Gently tapping across the fender with a body hammer will reveal hidden problem spots through a change in sound.

• Check alignment – Look down the fender’s length and across to the other side for any misalignment suggesting underlying structural issues.

• Review accident history – Discuss any past collisions with previous owners, especially late rear impacts that typically cause bacon fenders.

• Consider repaint history – Improper preparation or cheap paint could have masked developing damage that now requires correction.

Repair Options

The repair strategy depends on the type of bacon fender damage:

• Mild rippling – Applying heat and gently tapping out from behind may smooth small wrinkles and waves. Finish with primer, high-build primer and sanding.

• Moderate distortion – Pulling the fender with a stud welder, slide hammer or chains can stretch metal back into shape if the underlying structure is intact. Follow with body filler and sanding.

• Severe damage – Badly warped panels likely require cutting out the damaged section, fabricating a patch panel and welding in the repair piece. Requires experience and proper tools.

• Replacement – For extensive damage, it may be easier to source a new OEM quality replacement fender and swap it out rather than trying to salvage the original.

Seeking an experienced auto body repair shop is wise if repairs will require heat, pulling or fabrication work to avoid making the problem worse in inexperienced hands.

Step-by-Step Bacon Fender Repair

With moderate fender damage, here is a general process for smoothing out those unsightly wrinkles at home:

Supplies needed:

• Heat gun or propane torch
• Body hammer and dolly
• Stud welder
• Body filler
• High-build primer
• Assorted grit sandpaper

Steps:

1. Warm fender with heat gun to make metal more pliable.
2. Using dolly behind panel, gently tap raised areas with body hammer to flatten.
3. Make gradual, even taps to slowly flatten without cracking or stretching metal.
4. Pull indented areas outward with stud welder to flatten distorted spots.
5. Verify panel is smooth with hands and body hammer before filler.
6. Apply thin coats of body filler to low spots and dips. Allow to fully cure between coats.
7. Once filler is cured, sand smooth using a guide coat to identify any remaining irregularities.
8. Apply high-build primer over sanded filler and repeat sanding/priming until surface is perfectly straight.
9. Carefully sand final primer layer flush for fresh paint application.

Prevention Tips

Avoid future fender baconing with these measures:

• Install mudflaps to protect rear fenders from road debris.
• Correct minor damage immediately before it worsens.
• Maintain clean undersides to limit rust and corrosion.
• Check torque on suspension components to reduce vibration.
• Consider reinforcing panels underneath with fiberglass to add rigidity.
• Apply protective film or PPF to shield exterior body panels.
• Garage vehicle to limit environmental exposure year-round.

With diligence and care, those crunchy bacon fenders can be returned to their former glory. A combination of strategic heat application, gentle metal manipulation, structural reinforcement and finishing work helps transform rumpled ragged fenders back into show-worthy body panels. While it requires significant time and effort, the end result of smooth, straight rear fenders is well worth it.