If you search “how long have CVT transmissions been around,” Wikipedia has some interesting information. In 1879, Milton Reeves invented a CVT (then called a variable-speed transmission) for use in sawmills. In 1896, Reeves began fitting this transmission to his cars, and several other manufacturers also used the Reeves CVT.
The 1911 Zenith Gradua 6HP motorcycle used a pulley-based CVT. The Rudge-Whitworth Multigear was released a year later with a similar but improved CVT. Other early cars to use a CVT were the 1913–1923 David, a small three-wheeled cyclecar built in Spain, the 1923 Clyno made in the U.K., and the 1926 Constantinesco Saloon built in the U.K.
In the more recent past, we’ve seen CVTs come and go. We remember the Subaru Justy and the VT25 in the Saturn Vue. While they had potential, they lacked the durability, reliability, and familiar ‘good-transmission-feel’ we were used to. However, there is something unique and special about CVTs that keeps them close to the OEM drawing board. Let’s explore this mystical world.
THE GOOD SIDE OF CVTs
You may ask why CVTs still exist. Simply put, they offer the best engineering solution for powertrain management to deliver optimal performance and fuel economy under the broadest range of driving conditions. Here’s how that breaks down in lay terms:
- Optimum Engine Horsepower/ Torque Output: The CVT transmission can select the best gear ratio to keep the engine operating in its ‘sweet spot.’ Given that every engine has a maximum horsepower and maximum torque curve at a given RPM, the range between these represents the highest mechanical efficiency for the motor.
- Better Fuel Economy: With the engine operating in its most efficient range, fuel economy is improved over stepped-ratio transmissions since the gear ratios are seamlessly varied.
- Less Drive Train Stress: Since changing ratios in CVTs do not involve decoupling the engine from the transmission or reducing engine torque, there is less shock transmitted through the drive train.
CVT transmissions allow a more seamless transition between power demand and fuel-efficient driving, reducing the engine’s stress.
THE ‘NOT SO GOOD’ SIDE
In a perfect world, the CVT could be considered the perfect transmission (according to engineers)! However, there are trade-offs with this technology. Here are items worth consideration:
- High Operating Pressures: While most CVT units may operate as low as 100 psi at idle, the pressures to regulate the pulleys usually range from 200 psi at light to moderate throttle up to 1,000 psi under heavy acceleration or failsafe operation. Pressure takes a toll on the seals and related internal components as they age. Also, CVTs tend to run hotter, especially when driven aggressively.
- Limited Torque-Handling Capacity: The contact area of the push belt or chain is where the path of torque transfers. The ‘squeezing’ force the pulleys apply increases or decreases the holding force and varies based on demand. The actual torque capacity of a CVT cannot be changed based on the internal components that it was engineered to use. There are no performance builds!
- Normal Wear = Metal Contamination: CVTs use a push belt or chain to transfer torque. Just like friction in an automatic transmission or a manual clutch plate, the ‘friction’ material comes off the clutch surfaces and gets suspended in the transmission fluid. In the case of CVTs, metal from the belt or chain comes off and is circulated in the fluid. If CVT fluid is not serviced regularly, metallic debris can cause transmission overheating, sticking valves, and unit failure.
- Poor ‘Shift Feel’: CVTs ‘feel’ like they are slipping, which is normal! They also command lock-up as early as five mph. Some manufacturers add stepped ratio changes to the TCM programming to give the driver a ‘traditional’ automatic transmission-like shift feel. If this is a customer complaint, it will require customer education.
CVTs work best when paired with a small displacement engine. However, several OE manufacturers are placing them behind higher output engines successfully. Let’s look at one of the most popular OEMs and their uses of CVT technology.
NISSAN CVT HISTORY AND APPLICATIONS
Nissan, one of the leading Japanese automobile manufacturers, has a rich history of partnerships and collaborations. One such notable collaboration was with Toyo Kogyo (Mazda) and Ford Motor Company in the form of Japan Automatic Transmission Co., Ltd. (established in 1967). This joint venture focused on developing and producing automatic transmissions for vehicles. However, in October 1989, the company underwent a significant transformation and changed its name to JATCO Corporation.
JATCO offered CVT transaxles as early as 1992 in the Nissan March and Cube equipped with a 2.0L engine, followed by the 1.8-liter Primera and other models (not found in the U.S. market until 2003). The first vehicle equipped with a JATCO/ Nissan CVT in the U.S. market was the 2003 Murano SUV with a JF009E/ RE0F09A behind a 3.5L engine.
Over the years, JATCO has had several different CVT design platforms (figure 1). The significant change in platforms would be with the CVT 8 & 7 by eliminating the ratio control motor. Also, the Auxiliary gearbox was added to the CVT 7 platform, making it a two-speed CVT (“Power Glide”).
The name of their latest model, CVT-X, embodies this spirit of ceaseless advancement. The “X” stands for the “ultimate,” symbolizing JATCO’s commitment to challenging the unknown and embracing the possibilities of the future for CVT technology.
But if you look at the history and the commitment, you’ll see that JATCO is dedicated to CVT advancement. Nissan/Infiniti JATCO CVT platform lineup consists of CVT 1-X and are as follows:
- CVT1 (110 ft-lbs., 150Nm) JATCO JF009E / Nissan RE0F08A/B found in the Nissan 2007 & later Versa and the RE0F08B 2009 & later Cube, both with a 1.8-liter. (belt driven).
- CVT2 (184 ft-lbs., 250Nm) JATCO JF011E / Nissan RE0F10A found in the Nissan 2007 & later 2.0L-2.5L Altima, Sentra, Rogue and NV200 along with the RE0F10B 2011 & later 1.6L Turbo Juke. (belt driven)
- CVT3 (258 ft-lbs., 350Nm) JATCO JF010E / Nissan RE0F09A found in the Nissan 2003 & later Murano and RE0F09B 2007 & later Altima, Maxima, Murano and Quest, all equipped with a 3.5-liter. (belt driven)
- CVT7 (133 ft-lbs., 180Nm) JATCO JF015E / Nissan RE0F11A found in the Nissan 2012 & later Sentra, Versa, and Versa Note models with a 1.5/1.6/1.8L engine. (belt driven) (Note: there is a Wide Ratio RE0F11B and a JF020E that utilizes an auxiliary gearbox)
- CVT8 (280 ft-lbs., 380Nm) (High Torque)
- JATCO JF016E/Nissan RE0F10D found in the Nissan 2015 & later Juke with a 1.6L Turbo Juke, NV200 with a 2.0L, and the 2013 & later Altima and 2014-16 Rogue equipped with a 2.5L (belt driven/heavy duty).
- JATCO JF017E/Nissan RE0F10E found in the Nissan 2013 & later Altima, Pathfinder, and 2014 & later Infiniti QX60/70 with a 3.5L engine. (chain driven)
- JATCO JF017E/Nissan RE0F10H found in the 2015 & later Altima and Maxima with a 3.5L engine. (chain driven)
- JATCO JF017E/Nissan RE0F10J found in the 2015 & later Murano, Pathfinder, Quest, and the Infiniti 2014 & later QX60, all equipped with a 3.5L engine. (chain driven)
- Hybrid JATCO JF018E/Nissan RE0F02H, found in 2014 & later in Pathfinder, and in 2016 & later, Murano equipped with a 2.5L L4 supercharged engine. 2014 & later Infiniti QX60 equipped with a 2.5L L4 supercharged engine. (chain driven).
Some of these units need programming when installed. If it is a factory OEM new unit, the number engraved on the case will be the required program number (figure 2). Otherwise, a disc will be provided containing an updated program. Use the Consult 3+ factory scan tool for programming as needed.
With this lineup, we are approaching nearly a quarter of a century of CVT technology with Nissan/Infiniti/ JATCO, so we will be repairing these units for many years to come!
As transmission technicians, we either love, hate, or tolerate CVTs. Whatever category you are in, you must realize that CVTs are not going away. While the beginnings of the CVT transmission seemed to point it towards extinction, its technology has secured a long, prosperous future in numerous applications to come!
