Repairing Damage on a Diamond Frame

Repairing Damage on a Diamond Frame

We have a 1970 Chevelle with a diamond frame. It is only off by 3/8" in the center section, and the channel behind for the trunk support is also out by 1/4". Can I just use a simple jack on the inside of the frame in the opposite corners to straighten it out?

We have a 1970 Chevelle with a diamond frame. It is only off by 3/8″ in the center section. The rigid main front structure is straight. The rear of the frame behind the main structure for the rear end attachment is straight, but the channel behind for the trunk support is also out by 1/4″. Can I just use a simple jack on the inside of the frame in the opposite corners to push it the other way in these two areas? – Bruce Lavine, Lavine Inc., Miramar, Fla.

Question answered by: Richard Perry, OEM and strategic account manager, Chief Automotive Technologies

Diamond is not hard to fix, but it is important to understand how the repair will affect the rest of the vehicle. If you have diamond in the center section and attempt to move the right rail forward of the left rail in the center section, the front will sway to the left and the rear will sway to the right. That’s why you can’t really say that the front is straight if there is diamond in the center, because when the diamond is removed, the front will no longer be in the correct location.

In order to properly straighten the Chevelle, you will need a square, level center to align the end sections to. Using a ram diagonally in the center will get the rails to move, but you will not be able to control or monitor the rest of the vehicle while corrections are being made. Changes in height, width and length will be out of your control. Care will also be needed to make sure the cross members are not stressed, which could inflict additional damage to the vehicle.

For the best possible repair, load the vehicle onto a frame rack with a measuring system. Using this setup, you can carefully pull at strategic locations while monitoring your progress. Plus, you will be transmitting force from the frame machine to the vehicle, instead of pushing one corner of the frame against the other corner. Anchoring to a frame rack and using precise, controlled pulls greatly reduces the risk that the vehicle will be further damaged during the repair.

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