183 Chapter 9 Nonstructural Panel Repair Copyright Goodheart-Willcox Co., Inc. first. Make sure the base is stronger than the damage. The ram should always be set up to rest on the base. Tubes are snapped onto the ram to reach the damage. Figure 9-19 shows a typical setup inside a trunk. Notice that the base is the wheel house. The wheel house is curved and, therefore, may not be a stable base. To overcome this problem, a block of wood is placed on the wheel house and the base of the jack to spread out the force. At the damage correction end, a narrow attachment is installed. The narrow attachment can be used because the quarter panel overlaps the rear body panel. Because the damaged area is made of two overlapping panels, it is stronger and less likely a shock force. There are advantages to each type of corrective force. A constant force works better on strong folds, but a shock force is easier to set up and is adequate for minor damage. In order to apply corrective force, the ram or come-along must be hooked up to the vehicle and to a stationary object. The vehicle must be anchored to prevent it from moving. Figure 9-17 shows a power post setup with chains and floor pot anchors. The come-along can also be anchored to the floor pots themselves. As the come-along handle is cranked, the cable pulls the damaged panel into alignment. As we already know, a force will always move the weakest object. When the force is acting upon two or more objects (as with the come-along setup), the weakest object will move first. If the attachment to the vehicle is weak, it will give first. If the anchoring point is weakest, the anchor will give way. If the attachment and anchor are stronger than the damage, the damage will move first. Figure 9-18 shows a hydraulic ram being used to pull out damage. The vehicle is anchored so it cannot move. Likewise, the hydraulic ram cannot move. As the chain is tightened between the vehicle and the ram, the damaged area will move, lengthening the panel. The immobilizing position is important. Remember that a corrective pull will always try to make a straight line between the attachment and the pull. In most cases, a straight out pull is needed. This means that the pull should be at the same height as the attachment. As tension is applied to an anchored vehicle, the suspension may sag. To prevent this load on the suspension, insert blocking under the vehicle to maintain vehicle height. Blocking will keep the vehicle at the proper height so the pull will work as intended. Pushing Pushing with a four-ton hydraulic power set applies a constant corrective force to align damaged panels. For example, in a unibody vehicle that has been hit in the rear, the power set can be positioned in the trunk to push out the damaged rear body panel and quarter panel. If a quarter panel has been hit from the side and is shortened in length, the power set can be positioned inside the trunk to push the quarter panel to proper length, causing lift reaction to remove the damage. The power set ram requires a strong base. The force created by the ram not only pushes on the damage, but it pushes on the base as well. Remember that when force is applied, the weakest area will move WORKING SMART Goodheart-Willcox Publisher Figure 9-17. This power post is chained to the floor for light sheet metal pulls. Come-along Power post Floor pots Goodheart-Willcox Publisher Figure 9-18. The hydraulic ram on this pulling equipment provides a constant force to remove damage.