Category: Technology and Terminology

Explanations of various automotive terms and the technology under the hood.

Electrojector and D-Jetronic: Early Electronic Fuel Injection

Once considered exotic technology, electronic fuel injection has been around a surprising long time. In this installment of Ate Up With Motor, we review the origins of EFI and examine the relationship between the pioneering Bendix Electrojector, Bosch D-Jetronic, and the second-generation Bendix system that introduced GM to electronic injection in the 1970s — a complicated web of technology, business, and politics.

Seville and "Fuel Injection" badges on the right front fender of a Naples Yellow 1977 Cadillac Seville sedan (Aaron Severson)
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Electronic Fuel Injection Article

If you know anything about early automotive fuel injection systems, or if you’ve seen the Jay Leno’s Garage video about Per Blixt’s 1958 Chrysler 300D, you’re probably at least dimly aware of the short-lived Bendix Electrojector electronic fuel injection system. You might even have heard that it had something to do with the much better known Bosch D-Jetronic system, introduced about a decade later. However, there’s still much confusion about the relationship between these systems, and about what they have to do with the the electronic fuel injection system that Cadillac (and Chevrolet) used in the late seventies (in the Cadillac Seville and Chevrolet Cosworth Vega).

I have been delving into these questions (if only to distract myself from the still-calamitous financial situation), and I’ve come up with what I think is about the most definitive answer possible at this late date. I’m still fine-tuning some details and embarking on the search for appropriate illustrations, some of which I might need to make myself, but you’ll hopefully see it here in the not-too-distant future. (ETA:: The article is now done and will go live February 24.)

Don’t Call It Hydra-Matic: The Rolls-Royce and Bentley Automatic Gearbox

Although the Hydra-Matic transmission was first used by Oldsmobile and Cadillac, the final user was not a GM division, but Rolls-Royce, which used its own license-built versions of this highly successful GM transmission from 1953 to 1978. This included an unusual, short-lived variation for the early Rolls-Royce Silver Shadow and Bentley T-Series — the last iteration of the original Hydra-Matic transmission. In this installment of Ate Up With Motor, we take a look at the upper-crust British career of this venerable American automatic transmission.
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Secrets of the Simpson Gearset

If you’re familiar with transmissions like the Chrysler TorqueFlite and GM Turbo Hydra-Matic (among others), you may have heard of the “Simpson gearset.” In this installment of Ate Up With Motor, we look at the origins and function of the Simpson gearset and briefly introduce you to its inventor, the late Howard W. Simpson.
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Giving Slip the Slip: Lockup Torque Converters and Split Torque Automatic Transmissions

Fluid clutches — fluid couplings and torque converters — have many advantages for automotive transmissions, but with those benefits comes a cost: fuel-wasting hydraulic slippage even at cruising speed. Since the 1940s, automakers have come up with a variety of strategies for reducing or eliminating that slip, including series parallel “split torque” transmissions and different types of converter lockup clutches. In this installment of Ate Up With Motor, we take a look at how GM, Ford, Chrysler, Packard, and Studebaker have approached this slippery problem from 1949 through the late eighties.
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The MacPherson Strut

Although frequently misunderstood and often misspelled, MacPherson struts are one of the most common suspension systems used on modern cars, found on everything from the Proton Savvy to the most formidable Porsche 911 Turbo. In this newly revised and updated installment of Ate Up With Motor, we’ll take a look at the origins and workings of the MacPherson strut, including modern variations like the Toyota Super Strut, GM HiPer Strut, and Ford RevoKnuckle.
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Dynaflow, Turboglide, Roto Hydra-Matic, and Other Early GM Automatics

The Hydra-Matic, GM’s first fully automatic transmission, was a great success, inspiring a host of rivals — including some within General Motors itself. In this installment of Ate Up With Motor, we look at the origins of Dynaflow and Powerglide, the ambitious but ill-fated Turboglide and Flight Pitch Dynaflow (a.k.a. Triple Turbine), the later Controlled Coupling Hydra-Matic and Roto Hydra-Matic, and more.

AUTHOR’S NOTE: This article, originally written in 2010, has been extensively revised and expanded for 2016.

Dynaflow badge on a 1951 Buick Super Riviera © 2007 Aaron Severson

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Hydra-Matic History: GM’s First Automatic Transmission

GM’s original Hydra-Matic transmission was one of the most important innovations in the history of the automobile. It wasn’t the first automatic transmission, but it was the first one that really worked and its resounding commercial success paved the way for every subsequent auto-shifter. This week, we take a look at the origins of the Hydra-Matic and its originator, Earl Thompson, who also developed the first Synchro-Mesh gearbox back in the 1920s.

Hydra-Matic hood badge on a 1942 Oldsmobile B-44 club coupe © 2009 Aaron Severson

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A Weighty Issue: Shipping Weight and Curb Weight

A car’s weight has a dramatic effect on its performance, ride, handling, and fuel economy. Figuring out how much a car weighs should be simple, but the weights listed in brochures, road tests, and other sources can be contradictory and confusing. A vehicle’s specifications may list shipping weight, manufacturer’s curb weight, and gross vehicle weight ratings, all of which are quite different. To sort out this confusion, let’s look at what each of these terms means.

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