General Motors Turbo-Hydramatic Transmissions (Part III)

0

We return to the Turbo-Hydramatic once again today, and our third installment puts us at a critical point in the automatic transmission timeline. Government pressure on fuel economy and consumer performance demands increased dramatically in the years following the THM’s debut in 1964. This meant the creation of lighter, more compact and less expensive versions of the Turbo -Hydramatic compared to its flagship shifter, the THM400. GM branched out into models like the THM350, THM250, and the very problematic THM200.

In 1987, GM moved away from the traditional THM naming scheme and switched to a new combination of letters and numbers. Number of gears, layout and strength combine to turn the THM400 into a 3L80. But the heavy gearbox was already limited at the time to heavier truck applications; passenger cars have gone to four forward speeds after the dawn of the eighties.

General Motors was hot on its heels with the expensive class action lawsuit over the failure-prone THM200, filed in 1979. General had its transmission engineers make some changes to the THM200 with two goals in mind: to make it much more reliable, and more ready for future passenger car needs.

To that end, every problematic component of the THM200 has been replaced with an improved and redesigned part. While playing around with the 200, engineers added a convenient extra fourth gear with a 0.67:1 ratio. The improved box was called the THM200-4R when it debuted in 1981.

The 200-4R used a multi-housing bell housing so it accommodated the various rear-wheel-drive cars in GM’s lineup. The multi-case featured a double-bolt pattern, as opposed to the single-bolt pattern of a standard case which would only fit the specific vehicle it was designed for. The mounting locations on the 200-4R match those of the THM400. The new four-speed was nearly the same size as the old THM350, and the 200-4R became an easy upgrade for older models so equipped.

GM was sure the 200-4R was a better transmission and was also sure that their main cars needed a four-speed. Thus, the new transmission was rolled out in 1981 on the full range of full-size B bodies. The likes of the Pontiac Bonneville, Oldsmobile Delta 88 and Buick LeSabre benefited from the 200-4R. It was also used beginning in 1981 in larger C-body cars like the Buick Electra and Cadillac DeVille.

Further use of the 200-4R came in 1983 when it was carried over to mid-size G-body cars like the Buick Regal and Oldsmobile Cutlass Supreme. In 1985, when GM introduced its downsized front-wheel drive cars, the C body was renamed D. There the 200-4R continued in singular luxury use: the Cadillac Fleetwood Brougham.

The four-speed found itself a high-performance niche in the 1980s, when it became the transmission of choice for the Buick Grand National. In 1989 it was used for the Indy 500 Pace Car version of the Pontiac Firebird Trans Am. The 200-4R had a good run but was discontinued in 1990 after its last run in B and D body cars.

A year after the 200-4R, another four-speed appeared: the THM700R4. Beginning with the 1982 model year, the 700R4 was primarily used in Chevrolet and GMC vehicles. Its application was more limited due to its single-case bell, but was spread over many models given its developments. The transmission adopted GM’s new naming scheme in 1990 when it became the 4L60. Four speeds, longitudinal layout, resistance rating 60. For our purposes, we will use the modern denomination from now on.

Additional improvements between 1984 and 1987 included updated internals like the oil pump housing and ring gears. In late 1986 the 4L60 also received a new auxiliary valve body. The next major change came for the 1993 model year, with the arrival of the 4L60-E version.

The -E suffix meant that electronic controls had been added, which meant that the transmission relied on the powertrain control module (PCM) to tell it when to change gears. Recently modernized, the -E was implemented in GM’s trucks, vans, and SUVs in 1993. In 1994, use expanded to GM’s rear-drive passenger cars.

From there, the box was updated with a bolt-on bellhousing so it would fit on other vehicles much more easily. In 1998, all cars with a 4L60-E had a bolt-on bell, and the box expanded to more models. That year also saw the arrival of a new, more robustly designed torque converter. It was also revised in the 90s to comply with new OBD-II regulations.

The 4L60-E found its way onto an impressive number of different vehicles between 1993 and 2013. GM really stuck with four-speeds for as long as it could, while other manufacturers moved to five-, six-, or even eight-speed automatics. Longtime enthusiasts of the 60-E included the Chevrolet Suburban 1500, which used it from 1993 to 2009. The Camaro had four-speeds in its F-body form from 1994 until it was canceled in 2002.

Elsewhere, the Chevrolet Colorado used it from 2004 to 2012, and Australians found it in the Holden Caprice between 1994 and 2008. It was also used for GMT360 SUVs, including the exclusive and very different Saab 9- 7X. Its last use was in Chevrolet Express pickup trucks (vans still made today) in 2013.

During the heyday of the 4L60-E, a heavier version was introduced, the 4L65-E. It appeared in 2001 and was used exclusively with passenger vehicles with larger V8 engines – usually the 6.0 liter Vortec. Primary use was in the GMC Sierra and Yukon Denali, Cadillac Escalade and the ugly Hummer H2.

It was also shipped to Australia for use in 6.0-liter Holden Commodores and was sent to Kentucky for the 2005 Corvette. Quick shoutout to the 4L70-E, which was a 4L65-E with an internal speed sensor. The 4L60 and 65 were supplanted by the six-speed 6L80 and 6L90 after 2013. Back to the THM400/3L80.

As mentioned last time, the 3L80 saw its last use in 1990 in GM’s large vans like the G20 and Vandura. Although sturdy and popular, it was about time the three-speed gave way to a four-speed version. In 1991, production of the 4L80-E began. Along with electronic control, four-speed was the first major change to the old THM400 since its debut in 1964.

Unlike its predecessor which was to fill many passenger car roles, GM’s extensive use of the 4L60 meant that the 4L80 was confined to pickup trucks, vans and commercial-type vehicles. All 4L80s were built at Willow Run Transmission, Ypsilanti, Michigan (1953-2010). The 80-E was rated for up to 440 lb-ft of torque, with a maximum GVWR of 18,000 lbs.

GM put the 4L80 into service across its entire line of pickup trucks, in 1500, 2500, and 3500 versions of the Chevrolet Silverado, GMC Sierra, and Chevrolet Express and GMC Savana. It was also used in the almost forgotten 2500 version of the Chevy Avalanche. It lasted in minivan usage through 2009 and through 2013 in truck and SUV usage within GM.

However, like its three-speed ancestor, the 4L80 was used by companies outside of GM that needed a transmission capable of motivating significant power and weight. Most THM400 users simply transitioned to the 4L80 when it became available. One of the first manufacturers to buy the four-speed was Bentley and Rolls-Royce (then united as one company).

Bentley used it for the Eight, the Turbo R and all versions of the hugely expensive Continental coupe. Then, under BMW’s management, they continued to use it for all versions of the Arnage between 1999 and 2006. Rolls-Royce used it on their Silver Spirit and Silver Spur (1992-1998), in the part of their lineup that still used the THM400.

In 1992, the 4L80 was added to the Hummer H1 when the military truck was released for easy private use by people in Hollywood. A year later, Jaguar added it to its old XJS, where it would remain until the coupe’s run ended in 1996. It was also the engine for the high-powered XJR between 1994 and 1997. And it was associated with the company’s V12 sedans. (XJ12 and Daimler Double Six) between 1993 and 1997.

The British also had another use for the 4L80; perhaps its most surprising. In 1996, Aston Martin (a Ford property) called GM for some four-speeds for the new DB7. In fairness, the 4L80 was limited to straight-six versions of the DB7, as other flavors with V12 used ZF or Tremec cases.

The heavy-duty version of the 4L80, the 4L95-E, was used less. It was designed for use with vehicles up to 690 lb-ft of torque and a GVWR of 18,000 lbs. Use of the 85 was limited to GM vehicles equipped with the older Vortec 8.1-liter V8. It was used in the Express and Savana if they were fitted with a Duramax diesel engine.

It was also used for the Local Motors (2007-2022) Rally Fighter, the off-road buggy that was built between 2010 and 2016. The Rally Fighter paired a tiny Vortec 6.2-liter V8 with the 4L95 and was used in all 30 examples produced during those seven years.

And with the conclusion of the 4L60 and 4L80 in 2013, the Turbo-Hydramatic story came to an end. GM switched to six-speed transmissions for its goods, which it did not design alone. Cross-sectional applications saw the 6T70 jointly developed by Ford-GM and the 6L80 which was somewhat based on a ZF six-speed. Any suggestions for what Abandoned History transmission should cover next?

[Images: GM]

Become a TTAC insider. Get the latest news, features, TTAC catches and all things truth about cars first by subscribing to our newsletter.

Share.

Comments are closed.