181 Chapter 9 Nonstructural Panel Repair Copyright Goodheart-Willcox Co., Inc. Remove any screws that are found. If no screw heads are present, pull on an edge of the plastic panel with your fingers and try to look under it. Do not use a screwdriver or other pry tool when removing the trim. Prying on the plastic panel with a tool may distort the plastic and leave a stretch mark. A stretch mark is a visible white band in the plastic panel. If you can see clips under the panel, pull the panel off by hand. With the roof trim off, the headliner can be accessed. Carefully detach the headliner from the roof. The head- liner may be attached to the roof with magnets or Velcro. Most headliners have a semirigid backing. Folding this backing will permanently crease the headliner. The left and right edges of headliner may be able to be rolled together slightly and removed from a hatchback vehicle. In regular-cab pickup trucks, the headliner can be taken out through a door. In other vehicles, the back glass or windshield may need to be removed. If the headliner cannot be easily removed, drop it down on the seats and leave it inside the vehicle while the roof is being repaired. Roughing Out The panel repair process can be divided into two steps: roughing out and finishing. Roughing out restores the damaged panel to its approximate contour, and finishing completes the repair by restoring the exact contour of the panel. Several operations may be involved in the roughing out phase, including pulling, pushing, stretching, leveling, raising, edge alignment, and shrinking, as well as picking and filing. Pulling Longitudinal force can shorten a panel’s overall length. A pulling operation can be used to lengthen the panel. Pulling will remove folds, restoring the panel’s overall length. If a corrective force is applied at the point of impact, folds from longitudinal force can be removed as the panel is lengthened. See Figure 9-12. Lateral force can also shorten a panel by drawing the edges inward. A pulling operation relies on the lift reaction to restore panel dimension as the damage is pulled out. The lift reaction means that as the panel lengthens, the buckle unfolds, or straightens. A pull will always try to form a straight line between the pull loca- tion and the anchor location on the vehicle. The lift reaction has the greatest effect when there is a small angle between the attachment and the pull. When the angle is large, the lift reaction has less effect. See Figure 9-13. To set up a pull, an attachment is needed. An attachment, or hookup, connects the vehicle to the pull. Two attachments that are quick to set up are a clamp and a hook. Two clamps are shown in Figure 9-14. Each clamp grabs a portion of the unibody. Hydraulic power from the towers on a frame Goodheart-Willcox Publisher Figure 9-11. Pull on the masking tape handle to remove the taillight. Goodheart-Willcox Publisher Figure 9-13. A pulling operation relies on the lift reaction to restore panel dimension as the damage is pulled out. As the panel lengthens, the buckle unfolds. A—A small angle gives a large lift reaction. B—A large angle gives a small lift reaction. Pull Pull Anchor Anchor Small angle A B Lift reaction Large angle Lift reaction Goodheart-Willcox Publisher Figure 9-12. Folds can be removed from longitudinal damage by exerting a corrective force that restores panel length. Anchor Corrective force Point of impact