Say hello to project Baja B.O.M.B.er, the latest addition to an extensive family of project vehicles here at Four Wheeler. The Baja B.O.M.B.er is a 1999 Dodge Ram 3/4 4-ton 4x4 truck that we plan to turn into a desert-pounding chase truck. For those of you who don't know about Baja and the type of punishment chase trucks are subjected to, listen up: Baja is one of the harshest 'wheeling environments on earth. So follow along as we address the weak links and the high potential of the Cummins-powered Dodge Ram so that it can survive in Baja, and reveal some of the best-kept secrets of diesel-engine tuning and chassis-performance upgrades.
The automatic transmissions of Dodge Ram trucks are regarded as the weakest link in an otherwise stout drivetrain, compromised by poor electrical components and an inadequate lubrication system. With 50,000 miles on it, the 47RE transmission behind the torque-heavy Cummins turbodiesel in the B.O.M.B.er began, during upshifts, to hunt for the proper gear. Shortly thereafter, the indecisive transmission would randomly upshift. Clearly, it needed help.
For that help, we turned to the experts at Diesel Transmission Technology (DTT) of Abbotsford, British Columbia, Canada. Owner Bill Kondolay has been developing solutions to premature transmission failures for more than 20 years. Bill takes pride in his company's success in producing transmissions that are built for longevity and driveability. Many of the innovations that make a DTT 47RE the Rolex watch of automatics come from Bill's continued involvement in NHRA drag racing. It's this involvement that provides Bill with the access to the materials and services that make his products unique.
One of the problems with this transmission is that the internal components of the 47RE were engineered with a gas engine in mind. A gas engine makes power at higher rpm than a diesel does. This becomes problematic because the efficiency of the oil pump moving vital ATF through the various components of the system is directly related to engine rpm. This pump must supply specific pressures for everything to work properly. A higher pump speed means higher ATF volumes. In a gas-powered Dodge Ram truck you'll find the close cousin of the 47RE, the 46RE.
Just as its counterpart does, it has a pressure regulator valve that prevents excessive flow and Automatic Transmission fluid pressures from exceeding specific limits, which a high-revving gas engine is quite capable of producing. On the 47RE, the flow volumes are much lower, due to the lower revs of the diesel engine. Unfortunately, these lower volumes make a 47RE transmission run very close to its minimum-pressure requirements. This means that as your transmission breaks in, and dozens of tiny leaks are created around seal surfaces, the essential pressure drops below minimum requirements. Follow along as we learn how to correct these problems to make a reliable 47RE.
Step By Step
The first step of the process was to get pressure readings on the OEM transmission. To do this the DTT technicians installed a pressure gauge on the front servo port and took the truck for a drive. These measurements tell you where leaks are, as well as what problems might exist within the valvebody.
Bill's right-hand men Darrin Eby and Vinnie Parray got right to it and started by detailing how this truck is used.
With the transmission removed, the teardown process began. The dark color of the ATF suggests high amounts of metallic material were present. The DTT technician suggested that this trans had about 5,000 miles left before total failure. One look at the magnet inside the pan indicates how much damage had occurred.
With the pan off and the filter removed, a special tool was attached to the valvebody to bench-test the internal components for leakage. Next, the overdrive unit was removed. This back half of the transmission contains a heavy spring under 800 pounds of pressure. Careful, here-improper handling of this unit can cause serious injury.
These are the third-gear clutch discs, heavily damaged by slippage. Noticed the discoloration on the discs near the technician's hand.
This crud you see on the reverse servo is what floats around in the ATF and ruins transmission seals. It comes from the material on the friction bands as they wear. The only way to remove this substance is to change the ATF regularly.
With all the components removed and cleaned, a close inspection revealed tiny hairline scratches in the second-gear release servo that allowed pressurized ATF to leak past old seals, causing pressure loss, the primary cause of transmission slippage. Leaks like these prevent ATF from getting to the cooler and filter, as well.
To prevent leaks like these, DTT created its own servo that uses this special bushing that eliminates leaks caused by friction.
DTT goes to great lengths to ensure the quality of its components. The stock input shaft is in the background, the DTT improved design is in front. The billet input shafts and hubs were designed for heavy loads and extreme power applications. DTT says these shafts hold up to 800 hp and 1,600 lb-ft of torque.
The DTT output shaft shown on the left is vital for customers who plan to drag race and launch their trucks in 4WD. The design utilizes every bit of space available for extra beef. Notice the added thickness of the shaft material on the base of the DTT unit as compared to the stock output shaft on the right.
Notice the cross-hatching on the case, where the valvebody seals against the transmission. This is a poor surface to seal against without a gasket, as Chrysler engineers designed it. At DTT the surface is treated and if required, a custom-made gasket is used to prevent leakage.
Shown here are the various billet pistons available from DTT. These pistons, along with the pressure plate, change the OEM four friction materials to five friction materials. When combined with increased valvebody pressures, these changes increase the third-gear holding capacity by more than 40 percent over the factory setup.
These parts have vital design differences; using billet materials ensures longevity.1) DTT accumulator piston (billet aluminum)2) Stock accumulator piston (plastic)3) Stock band anchor (cast steel)4) DTT band anchor (billet steel)5) Stock band strut (spring steel)6) DTT band strut (billet steel)7) Stock second-gear lever (cast steel)8) DTT 4.4 lever (billet steel)
Bill recently introduced the DTT billet drum, engineered to prevent uneven wear during the apply cycle of the piston. Notice the two slots machined in the center of the DTT drum (arrow). The OEM cast-iron drum has a single slot, which causes the piston to wear unevenly. The DTT billet drum also increases the surface area by 67 percent. With the OEM drum and the DTT billet piston, you can upgrade to a five-clutch pack. This new drum also enables Bill to change the OE factory friction clutches from four to six. This, combined with the higher-pressure valvebodies, increases the holding capacity by more than 2.5 times over that provided by the OEM system.
Details like these are what make a transmission last longer. These are the seals DTT uses to prevent ATF from bypassing the accumulator and front servo pistons. These seals are made from Teflon and feature a stepped seam. These seals allow for complete sealing as materials heat up and expand. The OEM seals are made from steel, one is shown underneath the DTT upgrade.
To ensure against leakage, the torque-converter freeze plugs were staked, and then sealed with silicone. Specific torque settings are carefully adhered to and each transmission is thoroughly built according to specs determined by customer profile sheets generated for each truck. Each customer's needs vary, so every DTT transmission is custom-tailored.
Once all the new components were installed in the transmission, it was time to observe the valvebody build process. Again, working from a custom profile sheet, the valvebody builder assembles each unit using custom springs and valve combinations to achieve the driveability required by the customer.
After final assembly, the valvebody then undergoes three separate testing and calibration processes before it is deemed ready to be installed or shipped. Once our valvebody was mounted to the transmission, it was retested on the assembled transmission before being installed. Specific pressures were recorded and then the unit was serialized.
DTT uses only Mag-Hytec pans on its transmissions for its increased fluid capacity and its aluminum construction, which offers enhanced cooling abilities. We chose to use the Mag-Hytec regular version of the pan, which offers an additional 1.5-quart fluid capacity over stock.
The transmission was installed back into the truck and two electrical modules were interfaced with the PCM. One is called a voltage regulator designed to trick the PCM into thinking that it's seeing factory pressures, while in actuality it is allowing the transmission the benefits of the higher pressure DTT valvebody. The other electrical module is the DTT noise filter. It filters electrical noise, which can cause symptoms such as the transmission shifting in and out of gear, or the torque converter locking and unlocking.
This torque converter is from DTT and features furnace-brazed fin structures. This is considered the best method of construction for torque converters because it allows better efficiency and consistent weight distribution.
This torque converter is from another manufacturer and is spot-welded together. These welds would likely be the first part to fail under load.
Diesel Transmission Technology
Abbotsford, BC V2T 6H4