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The Jatco CVT used in the Dodge Caliber, Jeep Patriot, and Jeep Compass

Chrysler’s only continuously variable transmission (CVT), not counting hybrids, was used on the Dodge Caliber, Jeep, Compass, and Jeep Patriot, all built together, on the same platform, in the same plant.

JATCO CVT as used by Dodge and Jeep

The early version was criticized and a reprogrammed version, dubbed CVT2, replaced it. The CVT2 had more precise ratio control, and added manual control by simulating six gears. Chrysler claimed the CVT2 brought 6%-8% higher gas mileage than a traditional 4-speed automatic — roughly the same savings as the original CVT.

The CVT transmission used two V-pulleys and a steel push belt to vary the “gear” ratio. The transmission engaged the torque converter clutch almost immediately when accelerating, and kept it engaged, eliminating slippage. Continuously varying the transmission ratio allows the engine to stay in its most efficient operating range.

inside the dodge caliberThere was no part-throttle downshift; to get full acceleration, drivers pushed the gas pedal down further. The engine might not change rpm as one accelerated, making some feel as though there wasn’t any power.

The CVT was designed and built by Jatco, a joint venture of Nissan and Mitsubishi, using Chrysler electronics and programming. In the 2010 models, the CVT was given “tip start” and a moderate gas-mileage boost.

The CVT was used with both front and all wheel drive versions of the cars; an electronically controlled coupling managed front-rear torque split; it could run on 100% front wheel drive to save fuel, but brought in the rear wheels between 25 and 65 mph for better traction.

The Freedom Drive II Off-Road Package allowed the Jeep Patriot to be certified as Trail Rated; it included a version of the CVT with a low range (CVT2L) bringing a best-in-class 19:1 low ratio.

Why AutoStick was added

ImperialCrown wrote:

Having stepped ratios like a conventional transaxle goes against the original purpose of the CVT, but it comforts people who expect a downshift or upshift.

The CVT chooses the optimum ratio for the speed, load and throttle position at a given instant. As it s-l-i-d-e-s up through its infinite ratios, it can have the disturbing sensation of a slipping clutch, although it’s working perfectly. Software tweaks in 2007 further refined the “feel” for the ratio change.

dodge cvt

When DAF pioneered the CVT back many years ago, with a ~30 hp engine, it was controlled mechanically — and was viewed as the transmission of the future.

Ford left CVT development and went to 6-speeds after a couple of years (2006) because of the “feel” and software that they couldn’t remedy. I believe that Chrysler's/JATCO’s software, as of 2007, is close to optimum.

There is no internal transaxle “brake,” the abrupt deceleration normally felt with ordinary automatics.

Pat added: “One reason for including Auto-stick with a CVT is for driver control. This allows for a fixed ratio to lower the ratio for hill descent, or pick a higher starting ratio for moving from a stop under slippery conditions like ice or snow.”

Even before AutoStick was added, a “low gear” mode was included for these reasons.

Origins of the CVT in Dodge and Jeep cars

Stas Peterson wrote in March 2010:

Chrysler chose the CVT from Jatco as a relatively last minute choice, when the Chrysler six-speed dual clutch transmission was not coming along as planned. The only real issue is a fairly small overall gear ratio, between 4-5; other transmissions can have overall ratios between 4-7, so a smaller engine can have its power amplified by a wide overall ratio transmission.

To make the World Engines sprightly they need(ed) a wider overall gear ratio, and the CVT couldn’t deliver that, so the cars came across as noisy, thrashing, machines with little performance. That hurt sales.

Jatco has, since then, developed a wide ratio CVT with a wide and fixed final gear ratio, in a size suitable for micro-cars, and an overall gear ratio of just over 7:1.


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