Framework

A new custom rear frame was fabricated from mandrel-bent 2x3-inch rectangular tubing. The new frame welds to the front subframe and to the unibody.

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The floorpan of the unibody was notched to accept the new rear frame, thus providing additional ground clearance. The frame was welded to the unibody along its entire length for maximum strength.

A Rear Frame Adds Strength and Ties the Structure Together

The production ’68 Camaro combined unibody with front subframe construction. The rear suspension attached to the unibody. For any serious performance work, it is necessary to strengthen the basic platform to add rigidity and to provide secure attachment points for the rear suspension and a roll cage. The correct solution for this machine was a complete rear frame that rigidly attaches to the unibody and the front subframe.

Rick “Speed” Lefever fabricated the frame from mandrel-bent 2x3-inch, .083-inch wall thickness rectangular steel tubing. The frame extends to the rear of the vehicle and the roll cage attaches to it to provide additional strength and torsional rigidity. To further strengthen the structure the unibody is welded to the frame along the entire length of the frame. The floorpan is also notched in the passenger compartment for the frame rails. This provides extra ground clearance. Note the reliefs in the floorpan for the large diameter exhaust pipes too. These also add ground clearance.

The rear width of the frame accommodates large wheel and tire combinations, as well as the fuel cell mounting box. Note that the modification of the Camaro was done on a chassis jig to assure correct alignment. Such a fixture keeps things from moving around during the cutting and welding operations. This is also critical for determining the location of suspension mounts.

Additional work was done on the front subframe, cutting the front crossmember and tying together the lower A-arm mounting points. This work was done to provide additional front balancer and oil pan clearance since the engine now sits one inch lower than stock in the chassis. Note that the crossmember bracing is removable to permit oil pan removal while the engine is in the car – another nice feature.

2) With the engine set back six inches, a motorplate was fabricated to mount the front of the engine. Note the modification to the front crossmember. This allows the center section to be removed to provide the necessary space for oil pan removal while the engine remains in the car. This is an especially nice feature on cars where the engine remains in the stock location. In this case, it was also necessary to be able to lower the engine one inch for better handling, thus providing clearance for the harmonic balancer.

4) Additional bracing was added ahead of the crossmember to add strength between the lower control arm mounts and to keep the crossmember halves properly spaced when the center section is removed.