TRANSMISSION
The transmission in the LBMC needed to be built for severe duty. So we chose a few products from BD's line of tranny upgrades to improve the strock tranny.
The first thing we did was replace the stock valve body with BD's valve body. We eliminated shuttle shifting, increased line pressure and gained firmer shifts and better shift points. Next, we dumped our stock transmission pan and upgraded to BD's cast aluminum pan, which gave us more fluid capacity, which helps keep the fluid cooler. Then we removed the tranny and replaced the torque converter with a BD heavy-duty converter.
While the tranny was out, we swapped the stock flex plate for BD's heavy-duty forged steel flex plate. That concluded our transmission build, which was our biggest mistake to date on this project. With the power output LBMC would later have, we proved that the heavy dual Alcoa rear wheels were too much for the stock transmission output shaft. Under heavy fueling (around 550 rwhp) and aggressive acceleration, the output shaft snapped like a dry tree branch. It was necessary to replace the input, intermediate and output shafts with billet shafts. It would have been so much easier to do this in the beginning when we had the transmission out of the truck in the first place. The upgraded BD transmission was great. It had excellent torque converter lockup in all gears, with sharp, tight shifts. We noted increased fuel efficiency because the engine had a more positive, direct connection to the road through the transmission.