How Cummins And Dodge, Uhh Ram, Got Together

Dodge celebrates its 100th birthday next year and Cummins will reach the benchmark five years later; their shared 25-year anniversary also comes next year. While Chrysler has had their share of divorces and Dodge Trucks are now technically Rams with only a year of history, the marriage between Dodge/Chrysler/Ram and Cummins is arguably one of the best for both companies. But how did it start?

In 1981 Lee Iacocca was busy trying to turn around Chrysler, invent the modern minivan and get Dodge Truck out of the doldrums; the 1981 D-series had slightly changed sheet metal and a new Dodge Ram badge, but everything was interchangeable with a 1972. So V.P. Joe Campana created Truck Operations to get the truck business moving and wanted a diesel engine ASAP. Dodge had, from 1978-79, offered a Mitsubishi (another of Chrysler’s more favorable marriages) 6DR5-series four-liter six-cylinder diesel: It was reliable and fuel-efficient, but 105 hp and 169 lb/ft was a bit paltry by American standards, despite its use in 3.5-ton trucks in the home market.

Chrysler’s diesel engine search was worldwide. They talked to Detroit Diesel about a 6.2. They investigated the Navistar 6.9 but Navistar worried they mightn’t meet volume requirements after fulfilling Ford orders. Perkins had the 6.354 TE-series 5.8-liter turbo six. White engine company, Onan L-series and Deutz were considered, and Chrysler even built some diesel-ized 225 slant sixes. Then Cummins showed them their new, not yet in production B3.9 four-cylinder developed as a joint venture with Case.

Meanwhile, Cummins had been to GM Truck, but their President had come from Detroit Diesel where they still had an 8.2 to move. Ford’s plans were nearly in place and although Cummins proposed a five-cylinder B series, Ford went with Navistar.

Apart from vibration issues (which were much more muted on later injection-pump versions) Chrysler liked the B3.9 for its performance and fuel economy; they liked Cummins’ facilities and market research too. Chrysler thought an inline-six was too big and asked Cummins about a five-cylinder, which Cummins had already considered but again declined.

Much of the back and forth was between Cummins OEM Marketing Manager John Keele and Dodge’s Troy Simonsen, an engine specialist charged with making the Dodge diesel pickup Joe Campana was pushing for. Simonsen was watching the 6.9 Navistar and when Keele learned Dodge had considered the 6.9 the proverbial light bulb came on: The 6BT was designed to fit a medium-duty GM engine compartment that was relatively short. Maybe it would fit a Dodge.

Cummins asked Dodge for some engine bay dimension and component drawings and eventually decided they could fit a 6BT in a Ram. Cummins sent Chrysler a non-running engine to do some fitment engineering they could have done them-selves, but this was politically better since Chrysler wouldn’t have to credit Cummins with the installation. Chrysler chief engineers saw the model; what they did not see was any obstacle that would be a deal-breaker.

Chrysler gave a truck to Cummins to install a running engine, in part because Chrysler was still in recovery mode and didn’t have the engineering resources to fit a diesel engine in a gasoline pickup. Two big challenges were pricing and how Chrysler management would feel about it and how to integrate engineering done by an outside firm.

After a few tense months in which Cummins held their ground on pricing, in the middle of April 1985, it became apparent Cummins would be Dodge’s diesel supplier. Engineering went faster than administration and contracts, with six mules fit with diesels in May and five of them running in October. The first prototype they tested, a two-wheel drive, three-speed automatic, handily out-did both competitors’ diesels. Development Truck #1 remained on mule-duty for the addition of the after-cooler (6BTA) introduced in mid-1991 and the four-speed automatic. Restored as shown, the engine is in 6BT trim with modern gaskets, hoses and a size-too- small battery, but the transmission is the four-speed automatic.

The first manual-gearbox 4WD mule, while pulling a 10,000-pound trailer, broke a driveshaft on a steep hill start and was driven back to the shop in front-drive. This was just the first of many Dodge Cummins to spit out a driveshaft (or an engine mount if the driveshafts stayed together).

Obvious changes included moving the radiator forward more than four inches, stouter electrical systems right down to the battery tray, bigger exhaust that had to weave around a same-side front drive-shaft, fuel supply and filtering, a vacuum pump for brake assist, cruise and ventilation controls, stronger driveline, and brake and suspension changes for different weight and distribution. New Process, Tremec and Getrag were all considered for manual gearboxes but only Getrag could supply transmissions almost on time… they were limited in early production.

Cummins set up a Detroit facility to fit the engine accessories and deliver them to the plant on a just-in-time basis. Production was eventually scheduled for July 1988, for the 1989 model year, Simonsen projecting Dodge could sell 33,000 a year. Skittish executives watching Ford diesel numbers drop (because of model changeovers and the like) eventually tuned that number down to 10,000-13,000 units. From June 1988 to January 1989, dealers turned in 22,000 orders, darn near the 33,000 annual rate Simonsen had calculated, and by the first of December 1991, a total of 100,000 Cummins D/W-series trucks had rolled off the line.

All those B engines were built at the Cummins’ Consolidated Diesel Company facility in Rocky Mount, North Carolina. Engine engine production on the 6B began at the Columbus Midrange Engine Plant in Walesboro, Indiana, in 1992, and every Ram Cummins built since that time comes from there; engine number 2,000,000 was built in December, 2012.

In April 2003, 18 years after Cummins and Chrysler agreed to work together, they built the 1,000,000th Dodge Cummins pickup. They’ve turned out many more since then. UDBG

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