IHC’s macho muscle machines

IHC 66 series family of tractors — The power span of the 66 Series family was considerable, stretching from 32 up to 163 hp. Photo:
Wisconsin Historical Society

Over 50 years ago, while the general public’s attention was riveted on the space race, agriculture was fixated on a horsepower marathon.

Farmers, hungry for larger tractors, not only demanded bigger engines but also yearned for related technological advances in transmissions and hydraulics as well as creature comforts such as quieter air-conditioned cabs.

Anticipating this need for stout power plants, International Harvester had invested heavily in new engine design coming out of its Melrose Park development center.

True to form, the company’s highly talented engineers didn’t fail in that task; they turned out completely new six-cylinder diesel platforms comprising what would become a line of famous engines — the models D-360 (naturally aspirated), D-414 (naturally aspirated and turbocharged), and D-436 (turbocharged).

All told, this effort accounted for a $25 million investment in design as well as tooling and manufacturing.

The engines were rugged to a fault, employing seven main bearings. Among the many advances incorporated into their design were jet-cooled pistons, advanced fuel-injection pumps, torsional vibration dampers, and plateau-honed centrifugal cast-iron wet-type sleeves.

These features and manufacturing techniques, along with engineering devoted tocreating rugged engines, established these diesels as standards in the industry.

Thus was created the legendary “bullet-proof ”IH diesels so considered because of their outstanding durability. Still today, reconditioned D-436 engines, for example, are highly sought after, bringing $5,000 or more.

Big engines, new transmissions

Putting all the power generated by these new diesels to work challenged IHC engineers even further. Noted for developing and then launching in 1969 the first successful hydrostatic transmissions for tractors (dubbed the Hydrostatic Drive) an elite team of designers set to work upgrading the company’s slide-gear units.

In their place was created a four-speed synchromesh transmission that featured shift-on-the-go capability under load. International Harvester’s famous torque amplifier was offered as optional equipment with the new synchromesh transmissions.

Topping off power transfer advances was a new modular final drive with the planetary final
drive and axle carriers housed in one unit that bolted to the sides of the differential housing main rear frame. This approach provided an especially rugged final drive structure that was also easier to service.

What’s with those Black Stripe Internationals?

Toward the end of the 66 Series production, International Harvester felt the tractors needed some sprucing up to spur sales and move what would be the last of these models out of dealers’ lots. After all, a new line of tractors, the 86 Series, would be coming out late in 1976. Of the many changes considered, the one adopted had to be cost-effective and simple.

Enter a former Ford automotive designer who’d started working for IHC early in 1975. Bob Skyer’s response to creating a fresh look for the 66 series was simple. Skyer envisioned a logo change that consisted of adding a black stripe that ran the length of the side of the tractor hood and swooped up the front cowling. The tractor’s model number and the bold “International” name would be painted in white within the black stripe.

Farmers reacted favorably to the change and quickly snapped up the remaining production run of the 66 series. Known as the “Black Stripe” tractors, these models came out in mid-1975.

IHC Black Stripe 1066 — Wisconsin Historical Society

66 Series is born

These stout power train advances laid the foundation for the July 1971 introduction of International 66 Series tractors. At first, the line consisted of five models:

766 at 79 PTO hp. with a gear transmission.
966 at 95 PTO hp. with a gear transmission or 90½ hp. with a hydro-static (hydro) transmission.
1066 at 115 PTO hp. with a gear transmission or 113 hp. with a hydro transmission.
1466 at 133 PTO hp. with a gear transmission.
4166 four-wheel-drive with 140 hp. with a gear transmission.

To complete its horsepower line, International also brought out a line of gas-powered utility tractors — the models 354, 454, and 574 — which range in power from 32 to 52 hp.

The Model 1468, introduced in December 1971, was a standout in this product line as it packed a V-8 engine.

This engine was actually a modified version of a 550-cubic-inch IH truck diesel, which was unique due to its fuel delivery system.

When operating under no or low workloads, fuel was injected into only four of the engine’s cylinders. Under full load, all eight cylinders got fuel.

The 1468, at 133 PTO hp. with a gear transmission, stood out like a beefy lifeguard on the beach thanks to its chrome valve cover and tall twin stacks. IH didn’t miss talking up the model, touting it as “The Big Power Champ.”

The Steiger-built Model 4366 turned out 163 drawbar hp. from an IHC Model DT-466 diesel. Originally selling for $37,360, the 4366 would remain in production until 1976.

The 1066 was offered with either a gear (115 PTO hp.) or hydrostatic transmission (133 hp.).

The Steiger-built Model 4366 turned out 163 drawbar hp. from an IHC Model DT-466 diesel. Originally selling for $37,360, the 4366 would remain in production until 1976. PHOTO:

Wisconsin Historical Society

The 1066 was offered with either a gear (115 PTO hp.) or hydrostatic transmission (133 hp.). PHOTO:

Wisconsin Historical Society

At first, interest in the 1468 was high. However, eventually IH built just short of 3,000 of this model during the tractor’s four-year production run.

IH tried to revitalize interest in its V-8 tractor in 1973 when it brought out the 1568. Yet, like its predecessor, it sold poorly — with just 839 of these tractors made.

The 1568 introduction was accompanied by the 1973 introduction of two new 66 series models — the 1566 with 161 hp. and the 4366 with 163 hp.

Of these two, the 4366 marked a turning point in IH’s four-wheel-drive (4WD) design. While the 4166 reflected IH’s approach to 4WD using a rigid frame and wheel steering, the 4366 was an articulated tractor.

International had gained a financial interest in Steiger Tractor Company in 1972. It approached Steiger about building an articulated-steer model that would utilize IH’s DT-466 engine and other IH components. The 4366 would mark the end of the rigid frame 4WD for IH.

The IH-Steiger relationship continued during the remainder of International Harvester’s existence. Case IH, the merged company created by Tenneco’s purchase of IH’s agriculture equipment division in 1984, would acquire Steiger in 1986.

IHC 66 series tractor advertisement — Wisconsin Historical Society

The Farmall name dies

The year that the three new 66 Series models came out also marked the discontinuation of the vaunted Farmall name, ending an era that began with the introduction of the first Farmall Regular in 1924.

Farmall had become synonymous with International Harvester. However, IH management believed in 1973 the time had come to promote the International name for its product lines.

The name Farmall, however, wouldn’t disappear forever. Case IH brought the moniker back in 2003 to brand its utility-size tractors.

Dark clouds on IHC’s financial horizon

When Brooks McCormick came to run International Harvester in 1968, the company was turning out one successful technology innovation after another. In addition to introducing
the 66 series of tractors in 1971, the company also brought out its revolutionary Cyclo planter, which streamlined planting and enhanced seed placement accuracy.

However, troubles loomed, already threatening the company’s future. For example, in 1968 the International Harvester enjoyed a profit of $45.3 million, but that was just enough cash to meet dividend disbursements. Plus, the company had no reserve funds.

More importantly regarding its future, IHC had in the past handed out wage and benefit packages that were lavish but were proving to be a drag on the firm’s profitability and ability to innovate new products.

To make matters worse, the OPEC oil embargo hit in 1973, skyrocketing oil prices nearly 300%. The price of gasoline jumped from 38¢ a gallon in May 1973 to 55¢ a year later. The resulting economic recession led to a significant reduction in IHC truck sales.

McCormick set about working to right the IHC boat, selling the firm’s Wisconsin Steel subsidiary and ceasing production of the money-losing pickup truck division.

There were bright spots during this time. In October 1971 the company experienced the biggest farm equipment sales for any month in its history.

However, those successes were too little and proved inadequate. The remainder of the 1970s was a rocky time at best even after costs were controlled and sales reached record levels.

A labor strike in 1979 was followed by a depressed agricultural economy that greatly reduced equipment sales. Combined, these challenges eventually forced the company to be sold in 1984.

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