There is a tradeoff between chassis rigidity and total weight in any track car, and this one is no different. The lower radiator support from XV Motorsports has been proven to be a key upgrade for Mopar vehicles, but it does add some weight to the car. Adding weight is always cause for concern, especially when the weight is ahead of the front wheels. Given that this car is already nose heavy, we were reluctant to add any more weight that far forward. But the benefits of tying the frame rails together at the front of the car have been proven by XV on their four post shaker, so we decided to move forward and weld the support in place. With a little bit of extra fabrication work, the brace installation came out looking very clean and original. This car uses a radiator which is larger than stock, so the brace was slightly modified to provide additional clearance for the tanks. Once the support was painted black and the bumper re-installed, it is virtually impossible to see that it is there.
Transmission and Rear end
As part of our weight reduction effort, we went through the car and weighed all of the heavy components. One item we really noticed during this process was the original four-speed transmission, with its total weight of 117 pounds. This weight is carried fairly low in the car, but it is ahead of the center of gravity, so we were interested in reducing this weight as much as possible. We were aware of the weight savings possible with the aluminum case from Passon Performance, so we gave them a call. Passon developed their version of the A833 case several years ago, and it has been a very popular item for Mopar vehicles. Not only does Passon have aluminum versions of the main case available, but they also offer an aluminum side cover and an aluminum tail shaft. Our total weight savings after a transmission rebuild was right at 35 lbs.
Previously, the car was setup with a 3.23 rear gear and a close-ratio 2.47 first gear set in the iron A833. With the additional power of the new motor, the decision was made to switch to a 2.94 rear end gear. Combining this high rear end ratio with the close ratio set in the transmission gearing was going to make the car difficult to launch smoothly during street driving so we decided to go with a wider ratio gear set. To accomplish this, a 2.66 first gear was installed in the Passon case using a 308 front bearing and a 5.125-inch bearing retainer. Incorporated into the rear gear change was a swap to a 1967 B-Body 8-3/4 rear end. This was done to facilitate using the higher offset wheels at the rear. The slightly wider B-Body rear end places the high-offset wheels squarely in the rear wheelwells without the use of spacers.