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From derisive hoots to award-winning technology: How Ferguson and Roy Lunn developed the Eagle for AMC

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Photos courtesy the Patrick Foster collection, unless otherwise noted.

[Editor’s note: Bill Munro and Pat Turner’s extensively researched book on Ferguson, the British company that put four-wheel-drive systems under Ford Mustangs and plenty of other passenger cars, is out now, and while every word of “Traction For Sale: The Story of Ferguson Formula Four-Wheel Drive” is intriguing, the section detailing how Ferguson — with help from Roy Lunn – developed the four-wheel-drive system for the AMC Eagle, perhaps shows best how involved the company was behind the scenes of some significant automotive developments.]

As we saw in chapter 12, the Senior Jeep models, namely the Wagoneer, Cherokee and J-Series truck were offered from 1973 with Borg Warner’s full-time four-wheel drive system, Quadra-Trac. It was expensive to produce and noisy in operation and AMC wanted something cheaper and quieter. However, that replacement would come in a roundabout way.

In 1969, Kaiser Industries, Jeep’s owner since 1953, put the business up for sale. AMC’s Joint CEO, Roy Chapin told his fellow board member Gerald C Meyers to prepare a report on the feasibility of the purchase. Meyers advised against it, because Jeep was losing $10m a year. Chapin, however had faith in the brand’s export potential and the value of its military contracts. Further, the purchase would give AMC a place in the light truck market, which, unlike General Motors, Ford, Chrysler and independents like International Harvester, it had never had. So, in February 1970, Chapin went ahead with the purchase of the Jeep brand and set it up within AMC as Jeep Division. To run its engineering side, Chapin recruited an old friend of HFR, Roy Lunn.

The appearance in 1972 of the Japanese Subaru Leone, a small, cheap family sedan with part-time four-wheel drive, prompted Lunn to think that AMC could make something similar. AMC’s traditional market for passenger car sales was in the compact sector and the current model was the Hornet. In 1972, in the basement of his home in Michigan Lunn installed the Quadra-Trac driveline from a Jeep Wagoneer in a Hornet station wagon. However, the system’s noise and harshness, acceptable in the Wagoneer was aggravated by the Hornet’s unitary construction and the project was shelved. Incidentally, Tom Seaman of Morse Chain wrote to Tony Rolt around this time, suggesting that FFD should engage with Subaru, to see if the Japanese company was interested in the VC. No record exists of whether Rolt acted upon Seaman’s suggestion.

Sales of both V8-powered Jeeps and of AMC’s largest passenger car, the Ambassador slumped during the fuel crisis that followed the 1974 Yom Kippur war and the Ambassador was axed soon after. The company’s new compact, the Pacer had also bombed, so in November 1976, AMC top executive Gerry Meyers had lunch with Roy Lunn to discuss ideas for new products. Lunn had been following FFD’s activities with the VC with great interest and suggested they revive the four-wheel drive Hornet idea. Meyers agreed and in February 1977, Lunn went to England to discuss the project with FFD and GKN Birfield. He quickly came to an agreement with FFD for them to investigate the development of a four-wheel drive Hornet.

A prototype Eagle undergoes braking tests. Photo courtesy Ricardo MTC Archive.

GKN had licensed the US manufacturing rights to the VC to transmission manufacturer New Process Gear, a subsidiary of the Chrysler Corporation. Tom Seaman was crucial to the licensing deal from FFD’s point of view, as it was he who had introduced Rolt to Russ Bearss, who was running New Process Gear when Tony Rolt was endeavouring to get Ford to accept four-wheel drive for the Mustang. Bearss in turn made use of his connections in the industry to help make a connection with AMC.

Meyers envisaged that the new car, which he described as an ‘on highway four-wheel drive vehicle’ would have an annual production of between 40,000 and 100,000 units. Aware that the Hornet was a budget-price compact car with a sticker price of between $3,500 and $5,000, Rolt did express concern that the finished vehicle might have to sell for a significant premium over that, but AMC told them that the Jeep Wagoneer ‘sold like hot cakes for $10,000.’ This wealthier market was AMC’s target. Just as the Wagoneer had created the luxury four-wheel drive station wagon, this new version of the Hornet would be the world’s first family sedan, family station wagon and coupé with full-time four-wheel drive. Very little different in size from the Ferguson R5, it echoed what Ferguson’s attorney, John Ohl had said ten years or so before, about converting an absolutely standard American car.

The Hornet would be upgraded and restyled for the 1978 model year and given a new name, Concord. Its tag line would be ‘The luxury Americans want — the size America needs.’ The production four-wheel drive car would be based around the Concord and share that car’s trim options. In April 1977, a pre-production Concord Sportabout Wagon, with a 304ci V8 engine was shipped to FFD from AMC’s European operations in Holland. Under Keith Hamilton Smith, Jimmy Walker had already been set to work in March to design the layout, with four-wheel drive, using a VC and Mullard anti-skid brakes. The project had an estimated completion date some 12 to 16 weeks hence. The front differential was a prototype Salisbury unit, similar to that used in the Ford Capri (another use of those components acquired from Laycock!) mounted in a specially built alloy case and bolted to a fabricated subframe alongside the engine. The Hornet already had two features that facilitated the conversion, one being its steering linkage, which was in front of the axle centre line and the other that its coil springs acted on the top wishbones, which left a clear path for the axle shafts. AMC’s intention was to offer both 6-cylinder and V8 models, but only a V8 prototype was made, with drawings of the 6-cylinder model supplied to allow FFD to design the conversion for it. Hardy Spicer 87AC constant velocity joints and extended driveshafts derived from those supplied for the BL Princess were fitted. Building the prototype would cost AMC £20,000 and the extra driveline components would increase the total weight of the V8 vehicle from 3,444lbs (1,562kg) to 3,591lbs (1,629kg).

At Fort Dunlop.

Under Roy Lunn’s supervision it was tested fully in the UK from May, including undergoing skid tests in the wet at Fort Dunlop and in dry conditions at MIRA. The tests were undertaken with and without the Mullard ABS engaged. In all instances, ABS outperformed the skills of the test drivers, bringing the car to a standstill, square on and in a much shorter distance than when the test driver used cadence braking. The car was then sent to AMC’s plant at Kenosha, Wisconsin, where Lunn again oversaw testing. From there, in or around June 1977, AMC would make their decision whether to proceed.

AMC did indeed say yes, and Roy Lunn got the project started, attributing the speed at which the project came to fruition down to his racing experience. He said later in an interview with Autoweek magazine, ‘Racing teaches you a lot about timing. Arriving a day late for a race isn’t a successful way to go.’ But to Lunn’s advantage, the anticipated production date was put back to get the new Concord geared up for production.

New Process Gear designed a new production transfer case and centre differential, designated NP119, the number 9 at the end indicating the inclusion of a VC. The VC and centre differential assembly was of GKN’s design, with a bevel-type centre diff located inside the chamber, rather than FFD’s own design, which had a planetary diff with the VC mounted in tandem. It also featured a bevel centre diff rather than a planetary one, which had a torque split of 50/50 per cent. NPG’s reason for choosing this design rather than the FFD type was because it allowed them to better produce a transfer case with a neutral gear, which allowed the vehicle to be flat-towed. Flat towing was not an unusual practice in the USA, but towing a car with a VC in this way damages the VC. For the front axle, a Dana 30 differential was used in conjunction with axle shafts sourced from GKN’s Saginaw plant.

Introduced in 1979 for the 1980 model year, the car was named the Eagle. It incorporated full-time four-wheel drive, but not anti-skid brakes. There were three body styles: a 2-door sedan, a 4-door sedan and a 5-door Sportabout station wagon. The only engine option would be AMC’s 258 cubic inch six, because another fuel crisis had hit the USA, causing AMC to cease production of its V8 engine. The Chrysler 3-speed TorqueFlite automatic transmission was standard, connected to the NP119 transfer case, which, unlike four-wheel drive Jeep models, was single-range. Prices were in keeping with Meyers’ predictions, starting at $6,999 for the 2-door sedan, up to $7,549 for the 4-door wagon. A trailer towing package, which included a self-levelling hitch could also be had, which showed what market AMC were aiming for. The car was an immediate success, with in excess of 45,000 produced in the 1980 model year, boosting AMC’s production by 18 per cent over that of 1979. Don Sherman of Car and Driver, America’s prominent car magazine raved about it, saying:

‘It’s got to be the most impressive piece of automobile engineering in America today. What’s more, it drives well. There’s actually road feel in the steering wheel.’

Sherman’s colleague at C&D, Mike Knepper agreed:

‘With derisive hoots. That’s how I met the news about AMC’s plan to build a four-wheel drive Concord. … I’m pleased that AMC has finally built a car that no one – not the company, not the buyers, not anyone – has to make excuses for. The four-wheel drive has transformed the Concord: it drives, rides and handles like nothing else AMC has ever built.’

The magazine’s editor, Larry Griffin was also impressed, saying:

‘Something has happened over there in Nash Land that’s going to take some getting used to. American Motors has suddenly found the handle for building cars people want to buy. The Eagle is already back ordered for half a year.’

To Roy Lunn’s delight, he received an award from the Society of Automotive Engineers for the Eagle. With the Eagle, AMC had created a new market segment, predating the Audi quattro and Allroad and the Volvo XC90.

But all was not well. Complaints had been raised by buyers of the Eagle, about fuel consumption and high tyre wear, so halfway through 1981, AMC offered a new transmission option, Selec-Trac. This allowed the drive to the front axle to be disconnected, which saved fuel and reduced tyre wear. Selec-Trac’s downside was that the change had to be made while the car was stationary, so in 1984 a ‘shift on the fly’ option was incorporated. But the GKN arrangement of placing the VC concentrically with the centre diff proved to be flawed. The arrangement required that the plates in the VC had a smaller total surface area, which reduced the capacity of the unit in comparison to the HFR design. Also, the seals in the VC canister were inadequate and would leak when the VC was worked hard. The design of original vacuum-operated shift-on-the fly was not satisfactory. If the vacuum pipes were damaged or disconnected, the axle would not disengage, but the centre diff would disengage, resulting in damage to the VC. If the front axle stayed disengaged, the car could be without four-wheel drive when it was most needed. The vacuum system was replaced by a cable, resulting in a properly functioning system but by this time the Eagle had gained a reputation for unreliability.

[For more information or to purchase a copy of “Traction For Sale: The Story of Ferguson Formula Four-Wheel Drive,” visit or the Ferguson Formula page on Facebook. And for a special discount, enter the code HDN4x4. Publication date is May 29.]