THE LIGHTENING

side shot of lightening

Tom McBurnie, owner of the ‘34 Lightening was designed by Thunder Ranch and the Finite Element Analysis was performed by Chris Kilbourne at Barracuda Ltd. the manufacturer of Divinycell, the expanded polyvinyl foam used in the composite. For the catastrophic test, the ‘34 Lightening was first loaded through the door openings with a 3500 pound central load. This load was increased by 4.6 times before failure occurred. This structural analysis was made prior to the addition of the center cooling tunnel which is 7 ” tall, 5″ wide and runs almost the entire length of the car. The center tunnel equals the strength of the composite in the rocker boxes that should extend the load carry capability before failure by more than an additional 10,000 pounds.

To eliminate body torque, the complete body/belly pan is one piece, and the transition from rockers to body side panels a gentle radius. Further torsional stiffness is achieved by a two piece rear engine bulkhead, a bulkhead at the cowl, a small bulkhead that doubles as the lower fan shroud, and a second floor between the engine and cowl bulkheads at door sill height. These bulkheads and floor tie the strength in the skin, rocker boxes, and central tunnel together to make the only street car body produced with its high strength-to-weight ratio in the world. The complete monoque body/chassis weighs just a little more than 200 pounds.

The suspension is also unique. The front suspension bolts directly to the composite through aluminum bobbins that are laminated into the carbon fiber and Kevlar composite as the body was made. The system of through bolting in a fiberglass automobile laminate using bobbins was first done by Colin Chapman at Lotus in 1957. The ‘34 Lightening uses an upper A arm and lower control arm in front with a single Aldan shock mounted between and attached to extensions on the lower control arm. A remote shock reservoir is used so that shock air expansion takes place away from the actual shock valving.

The lower control arm also is splined onto the torsion bars that lay in the belly of the front compartment. These two parallel torsion bars are mounted into a steel housing and use bronze bushings as bearing surfaces. The torsion bars extend through the lower control arms and into the composite in front where another bronze bushing is located. In all, each control arm/torsion bar assembly is mounted on three bronze bushings.

The upright and spindle mount a ‘70-’77 Chevrolet Camero hub/disc assembly and braking provided by a Wilwood Dynalite II caliper and CNC’s dual master brake cylinder set up. The steering is a modified Ford Escort rack and pinion.

At the rear the engine cage comprises the only steel frame in the car. The engine cage is necessary not for strength; but because we want to offer a variety of power plant options. Therefore, the engine cage is a device that currently allows the buyer to use a GM 4, 6, or 8 cylinder front drive power system (engine, transaxle, half shafts, uprights, and brake calipers) that have been produced from 1985 to present. The Thunderod featured in the Street Rodder series (August 95 to December 95) uses the 1995 Oldsmobile Aurora V-8 for its power.

Thunder Ranch