Transmission Fluids and CVTs
When we were young, there were really only two kinds of vehicles: those with an automatic transmission and those with a manual transmission. Once you learned how to operate a clutch and shift gears without grinding, it seemed like nothing could be more fun.
For those of us in the lube business, we’ve since learned that the transmission world is a little more complicated, especially with regard to fluid needs. On the automatic transmission side of things, there are some that call for GM Dexron III and others specifying Dexron VI. The latter are seeking to contribute to higher standards of fuel efficiency and therefore aim for internal protection while offering a greater fluidity through lower viscosity. This differentiation is occurring with the other automakers as well.
Then you get into the manual transmissions, and the designs have begun to vary significantly, from traditional to synchromesh, to three-speed, four-speed and more-speed transmissions.
Rex Roy, in a 2011 Popular Mechanics story titled “Gears Galore: How Many Speeds Is Too Many?” wrote, “The latest craze amongst manufacturers is the eight-speed automatic transmission. BMW, Audi, Lexus and Porsche currently offer octo-geared automatic transmissions with traditional torque converters and planetary gearsets. Ford has committed to manufacturing its own eight-speed automatic in-house.” Which begs the question that Roy raises, “What’s with the rush for more speeds, and how many is too many?”
Bring in the hybrid partial-electric transmissions, and you wonder what they’ll think of next. I first encountered a partial electric tranny at the New York Auto Show a few years back. The hybrid tranny runs the car like an electric golf cart until you reach 25 mph, at which point the engine kicks in. It’s useful for moving your vehicle around a parking lot, or a long driveway, with zero emissions.
The aim of this article is to discuss yet another method of transmitting the power of the engine where the rubber meets the road, the continuously variable transmission, or CVT. The reason I wanted to address this is because many installers have become reluctant to service CVTs. By understanding how they perform and their special needs, perhaps CVTs can be seen as a revenue opportunity to be embraced rather than a concern to be shunned.
Why are CVTs becoming more prevalent? What are the advantages of CVTs?
The primary reason for CVTs’ growing popularity is fuel efficiency, with Asian OEMs are leading the charge. Since meeting CAFE requirements is a top priority for the auto industry, they are looking for any efficiency gains they can find. CVTs have improved efficiency over traditional automatic transmissions because they have “infinite” gear ratios, allowing them to do a better job of keeping the engine rpm in the sweet spot for fuel economy. This continuous shifting also leads to quieter operation because the engine doesn’t rev to higher rpms before shifting, and the ride is smoother since drivers do not feel the vehicle shift through gears like a traditional automatic transmission.
What makes CVTs different from other transmissions?