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Overdrive 4L65-E Transmission - Bionic Transmission

Inside GM's Stronger, Faster 4L65-E Transmission

By Barry Kluczyk

And, yes, the L80 and L85 are direct descendents of the venerable Turbo 400-which is, of course, merely a heavy-duty, longer version of the Turbo 350. So, they should fit, right?

The L80 and L85 will fit were Turbo 400 have gone before, but if you're running a small-block the L65 or L60 is the way to go, says Jim La Fontaine, lead systems engineer for transmissions at GM's Performance Division.

"The L80 and L85 are better suited to big-block applications," says La Fontaine. "The L65 is suited to small-block engines; it's designed to fit with the drivetrain of a small-block-powered vehicle to make installation relatively simple."

The L65 has another important advantage over the L80: it's a lot lighter. A 4L65-E weighs about 55 pounds less than an L80 or L85.

Cable X
Abbott Enterprises' quick fix for using an electronic transmission with a mechanical speedometer

Abbott Enterprises, of Pine Bluff, Arkansas, has a solution to the dilemma of the use of an electronic transmission and a mechanical speedometer. Its Cable X converter transforms the electronic signal of the transmission into a motor-driven output that drives a traditional mechanical speedometer.

The $300 Cable X is a box with electronic connections on one side and a mechanical cable hook-up on the opposite side. A motor inside the box turns the speedometer cable based on the signals received by the electronic transmission.

"It's an easy install," says Abbott's John Ware. "There are just three wires for the transmission and simply the cable hook-up for the speedometer."

Ensuring the speedometer's accuracy falls to adjustable dip switch settings on the Cable X box, which calculate the correct number of pulses per mile based on the transmission gear (number of teeth), axle ratio and tire size. Abbott Enterprises says the device is accurate to 2 percent of the transmission's electronic signal.

"The dip switch programs the correct speed formula," says Ware. "Overall, it's a simple procedure."

Simple also describes the idea to bring the Cable X to the enthusiast market. Previously, Abbott Enterprises' existence depended solely on the trucking industry. The company manufactures a variety of tachographs and other speed/timing equipment for the over-the-road crowd. But the growth of GPS navigation and tracking cut into Abbott's core business.

"We had a couple of car enthusiasts at the company who suggested the Cable X would be great for older cars using modern transmissions," says Ware. "Frankly, we didn't think there would be much of a market for that application, but the phones haven't quit ringing. The response has been terrific."

Abbott Enterprises Inc.
901 W. Fourth Ave
Dept. SC
P.O. Box 9026
Pine Bluff, AR 71601
(870) 535-4973

History of the L60-Series TransmissionToday's 4L65-E and 4L60-E transmissions trace their lineage to 1982 and the introduction of the 700R4, one of General Motors' first production automatic overdrive transmissions.

Two versions of the 700R4 appeared: one with a 60-degree bellhousing bolt pattern and another with a 90-degree bolt pattern. And though the advantages of lower cruising rpm and higher fuel economy were widely praised, the early 700R4s suffered from weaknesses that caused many to fail in even the lightest-duty applications.

By the '87 model year, the 700R4 had been internally upgraded and the problems that plagued earlier versions of the engine disappeared. In the '90s, the name changed to 4L60, reflecting GM's new nomenclature for all its transmissions-"4" for four-speed, "L" for longitudinal (rear-wheel drive), "60" denoting the torque capacity rating. (The "E" was added when the transmission was converted to electronic control.) The 700R4 and 4L60 are internally similar, including gearing.

By Barry Kluczyk
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