Slip-Slidin’ Away: BD’s A-518 Trans Upgrades

June 13th, 2011

By Kevin Wilson

Photography: Terry DeLong

While it ain’t much to look at here, our Project 1st Gen is well on its way to becoming a great daily driver and possibly even a Diesel World cover truck.

Diesel World’s Project First Gen field find has been a slow work-in-progress. The truck is being used as a teaching tool for a vocational paint and body school, and based on what you can see here, there was plenty of work for the students to accomplish. With the truck in the paint booth for prep and paint, we figured it was a good time to address some of the mechanical issues on the truck––namely the well-worn automatic transmission––before we turn up the power on the 12-valve.

Like most first-gen Dodges, the truck is fitted with the A-518 automatic, which is basically Chrysler’s solid 727 TorqueFlite with an overdrive tacked onto the back of it. All 727s were fitted behind gasoline engines–– including big blocks such as the hemi––in the heyday of hot rodding. When Chrysler needed a four-speed automatic, they just added an overdrive unit to the 727 TorqueFlite and called it the A-518.

While the truck was headed to the paint booth, the A-518 automatic trans was pulled and sent over to Dave’s Diesel for a rebuild that used BD’s Stage 4 Master Kit.

According to BD Diesel, of Abbotsford, British Columbia, Canada, the first-gen A-518s had some issues when mated to the 12-valve Cummins. First and foremost, the factory torque converter is essentially a “loose” gas engine torque converter, which was prone to slipping badly when used in conjunction with an engine brake. The problem was compounded by the fact that the A-518 did not use a “lock-up” torque converter, which generated even more heat. That slippage resulted in massive amounts of heat and oil foaming that would eventually kill the trans.

As a result, the company developed a line of upgraded trans parts for the A-518 to deal with some of the early design flaws. The heart of the product line for the A-518 is a BD torque converter with a much lower stall speed and a more efficient internal design, as well as a stronger billet stator. The BD torque convertor also utilizes a heavy-duty, stamp-forged steel cover that eliminates warpage under high torque loads such as towing. According to BD, these torque converters are designed to handle 1,000 lb/ft of torque.

The Stage 4 Master Kit comes complete with all the components you’ll need to upgrade the trans, including new High Energy bands, High Energy frictions discs and a 3.5 kickdown lever for improved shifting, not to mention all the gaskets and assembly goodies.

The company has also developed a line of rebuild kits for the do-it-yourself enthusiasts who would rather upgrade the trans they have than buy a new one. The company’s Stage 4 Master Kit includes such upgrades as the BD 47RH/RE gear train assembly, which was used in later Chrysler diesel transmissions. The kit also comes with BD’s High Energy friction discs and clutches, High Energy bands and 3.5 kickdown lever. The master kits all include basic rebuild parts and gaskets, as well as the upgraded internals to beef any diesel trans.

The folks at BD also sent us one of their deep-sump, cast aluminum trans pans that not only holds more fluid, it also stiffens up the transmission case. In addition, it has a drain plug and is drilled and tapped for a trans temp sensor.

The heart of the A-518 upgrade is BD’s diesel torque converter with furnace-brazed turbines and impeller fins and a heavy-duty, stamp-forged steel cover to eliminate warping.

Because taking apart an automatic transmission, getting it back together and having it work again is not something for the average driveway mechanic, we took our A-518 trans up to the experts at Dave’s Diesel, in Angola, Indiana, for the tear-down, inspection and installation of the BD Master Kit. The whole operation took the greater part of a day, but we are confident that when Project 1st Gen is back on the road again, the trans will be up to the task of handling the truck’s newfound horsepower and torque.


BD Diesel Performance


Dave’s Diesel


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