Fender benders occur every day. Someone changes lanes without looking and bam! There’s a crash. If you’re repairing these cars, the fender repair will be an easier fix than the quarter panel because the fender can be removed and replaced.
Rear quarter panel work will require more time and applied skills than the fender job. Welding will be necessary when this panel is being replaced. Also required is an exact paint match with the door, B-pillar (if applicable), roof, fascia and trunk lid. This review of quarter panel replacement is focused on a late model Dodge Challenger.
The Use of Heat
Before we get into the specifics of quarter panel replacement, a warning concerning the use of heat is in order. The FCA US LLC engineering position on the use of heat during collision repair is as follows:
Body panels or frame components sustaining damage, which are to be repaired and reused, must be repaired using the cold straightening method. No heat may be used during the straightening process. During rough straightening prior to panel replacement, damaged panels or frame components may be heated to assist in body/frame realignment, but the application of heat must be constrained to the parts that will be replaced and should not be allowed to affect any other components.
This “no heat” recommendation is due to the extensive use of high-strength and advanced high-strength steels in FCA US products. High-strength materials can be substantially and negatively affected by heat input, which will not be obviously known to the consumer.
Ignoring these recommendations may lead to serious compromises in the ability to protect occupants in a future collision, reduce the engineered qualities and attributes, and/or decrease the durability and reliability of the vehicle.
The Rear Quarter Panel
The rear quarter panel is not a bolt-on body component like a door or trunk lid. It is a large body side section, extending from the trailing edge of the doors to the rear bumper. It is part of a welded assembly commonly known as the body side aperture. This assembly also includes the framework for the doors and side windows. There is a right side and a left side aperture.
These two assemblies, along with the other components such as the vehicle’s underbody, rocker panels, frame rails, back panel, tail lamp panel and roof panel, are welded together to comprise the unibody.
Because the rear quarter panel is a component of a welded assembly, the energy from the body-damaging collision may be spread throughout the unit. Therefore, a thorough inspection of the damaged area is necessary. Remember that the rear quarter panel is one of the boundaries of the trunk and door openings alike. Check the opening/closing and the margin fit of the doors and trunk. Tail lamps, rear bumper fascia and rear bumper reinforcement might also have suffered damage.
The most important consideration is the structural alignment of the unibody. It is critical that alignment be verified with 3D measuring systems. If alignment is off and not corrected, it will be nearly impossible to install the replacement panel correctly.
Quarter Panel Removal
Before you start cutting sheet metal to remove the quarter panel, the components adjacent to it must be removed. This includes the deck lid, weather-stripping, rear tail lamps, rear wheelhouse, splash shield, compression link and spring. If you are removing the driver’s side panel, the fuel door must be removed from the quarter panel to access the inlet tube feeding the fuel tank.
Quarter panels are spot welded in place. Drilling through these spot welds is one method of removal. A plasma cutter or cutoff wheel can also be used. Remember the corporate warning on the use of heat in performing body repair work. Another removal tool is the air chisel.
Try to follow the contour of the panel while trying to make all cuts in straight lines. Transfer the cut lines to the new panel and trim to fit as necessary. Be as precise and accurate as possible.
Next, position the replacement panel over the damaged area of the quarter panel. Trace the outline of the replacement panel on the existing one. Remove the replacement panel and carefully use your air chisel to cut out the damaged area. Be sure to cut along the inside edge of your scribed line. Any areas that are bent can be flattened using a hammer and dolly.
After you’ve finished removing the quarter panel, clean the cut edges with a high-speed grinder. Be sure the edges are clean and free of rust. If any rust does exist, apply a rust-arresting compound.
Quarter Panel Installation
Properly preparing the rear quarter panel before installation is essential. All new body panels are coated with electrocoat primer. This coating must be removed ¾” high along the mating edges of the panel in order to properly weld bond it into place. Failure to do this will prevent the proper adhesion of adhesive and effect flow of weld current, resulting in an insufficient weld.
Dry fit the quarter panel with the adjacent body parts and hold it in place with locking pliers or sheet metal screws. Check the fit and then install the trunk lid (Figure 1). Apply the structural adhesives that are required using the slowest curing product . This will give adequate time for final wet fit. Fasten the panel with self-tapping screws to hold it in place.
With the panel in place and the adhesive applied, resistance spot-weld the panel to secure it. Then, use a MIG welder to do the final butt welding. Remove the self-tapping screws. Grind down the welds and fill in any surface imperfections with body filler to complete the job. Seam seal the area before painting.
Recheck the gap and flush on the trunk lid and side door (Figure 1). Trunk lid adjustment is done by loosening the screws that secure the upper hinge bracket to the trunk lid (Figure 2) and moving it to the correct position. The lateral door adjustment is done by loosening the hinge-to-hinge pillar fasteners one at a time and moving the door to the correct position. The vertical adjustment of the door position can be done by loosening latch striker bolts (Figure 3) and moving the door to the correct position.
The finish of the new panel is very important. Painting can present some problems. The new paint will have to blend into the existing paint seamlessly. Also, it will have to match the paint on the door, roof, rear fascia and trunk lid. Make yourself a sprayout of the color and verify the match before spraying any paint on the vehicle to ensure a perfect job. Refer to the six FCA US approved refinish paint suppliers (Axalta, Akzo Nobel, BASF, PPG, Sherwin-Williams and Valspar) for detailed paint application recommendations.
It’s important that, when working on a FCA US LLC vehicle, you are fully aware of the factory positions regarding sensitive procedures and parts sources. Visit: www.MoparRepairConnection.com for those factory official positions that can save you time and trouble on your next body repair.