BD tests every transmission...
BD tests every transmission it builds on an in-house transmission dynamometer. The technician makes sure the unit is performing correctly through a variety of tests before it is shipped to the customer.
When Dodge introduced the Cummins engine, it represented a major breakthrough in power, torque, and fuel economy for Dodge pickups. It also was the beginning of what would turn out to be an ongoing struggle with transmissions. Before long, the word was out: Dodge transmissions weren't always able to stand up to diesel torque, especially in heavy-hauling or towing applications. Subsequently, the factory began implementing minor improvements in an effort to stem the tide of transmission warranty claims, finally getting it right only a couple of years ago.
One thing the factory didn't concern itself with, however, was the burgeoning diesel performance market. While the latest Dodge transmission, the 48RE, was able to handle the stock power levels, failure began to shake its ugly head when power was increased beyond 60 hp or so. It soon became evident that with engines that were capable of more than 1,000 lb-ft of torque, something had to be done, and BD Diesel Performance has done it.
Here, the stock torque converter...
Here, the stock torque converter turbine housing (left) is compared to the BD housing, which features furnace-brazed fins. You've probably heard a lot about furnace-brazed fins in the past, but may not know what they are.
If you look closely, you can...
If you look closely, you can see that the factory fins are merely bent and staked into place. The BD fins are actually brazed in place for greater strength.
Also note that the stock turbine...
Also note that the stock turbine housing uses a hub which is riveted in place.
BD has been at the forefront of the diesel industry since it began, offering an ever increasing line of performance products to answer the needs of the evolving Cummins market. As problems with the Dodge 47RE and 48RE transmissions began to surface, the company initiated an extensive research and development program to determine the weak links in these transmissions, and then methodically solved them to arrive at some truly dependable designs. Today, BD offers everything from exchange transmissions to custom-built race transmissions and torque converters, made on the premises and designed to handle the outer limits of diesel torque. They even back their transmissions with a one-year parts, labor, and freight warranty, and offer an optional three-year warranty as well.
BD welds the hub in place,...
BD welds the hub in place, which is why there are holes where the rivets used to be.
The stock stator (left) is...
The stock stator (left) is made from cast aluminum, and uses a plastic spacer in the center. BD's stator is made from billet aluminum, and is machined at its center for a Torrington bearing. Also, note the difference in impeller blade angle between the two units. BD has found that the more extreme angle of the stock stator blades increases torque converter stall speed, which is good in a high-performance gasoline engine, but wastes low-speed torque on a diesel. By reducing the angle of the impeller blades, stall speed is decreased and low-speed torque is increased.
The 47RE and 48RE torque converter...
The 47RE and 48RE torque converter covers have lugs which are welded to the cover at the factory.
We visited BD to learn what they do to their transmissions to make them live behind high-torque diesel engines. From the torque converter to the tail shaft, BD's transmission department walked us through the mods that they perform. As you'll see, they amount to much more than a recalibrated valvebody and some extra clutches; these transmissions are literally reengineered. And though we're focusing on Dodge transmissions in this article, it's worth mentioning that BD offers the same services for the current crop of Ford and GM transmissions as well.
If you plan to bolt serious horsepower onto your diesel, save yourself some trouble and consider a performance transmission designed to handle it. The factory may be able to experiment with the thresholds of transmission failure, but we're betting you can't afford to do the same.
BD has found that the intense...
BD has found that the intense heat used to weld the lugs to the outside can actually warp the clutch surface on the other side.
This results in high spots,...
This results in high spots, even cracking.
The close-up shows these spots....
The close-up shows these spots. BD covers incorporate mounting bosses, rather than welding them on after the fact.