eli5: Why does a CVT transmission still “shift” if it can be in any position and move seamlessly as they say?
In: 579
Hi OP,
Actually, it is a bit more complicated than “it’s done to fool non-CVT drivers”, at least in certain cases.
Take the Nissan Sentra, Versa and Micra. Between 2010 and 2016 they used a particular CVT transmission made by Jatco (who supplied Subaru, Mitsubishi and others) called the JF015e. When it was introduced, it was hailed as an innovative design. In an effort to reduce weight and size, two things were added: two separate high/low clutches, and an additional planetary gearbox. This allowed for space savings of over 15 percent — not insubstantial in economy cars — and allowed for neat tricks like not requiring the belt to turn the other way when in reverse. The consequences of these separate clutches and gearboxes engaging, though, is noticeable and predictable changes in engine RPM. People would say “huh, feels like my CVT is changing gears”, and if they had a JF015e… in a way, they were right!
Now it turns out that the JF015e was a cursed design. It was EXTREMELY intolerant to debris shed by the belt — a normal occurrence in CVTs — and this would circulate in the fluid and score the bores of the solenoids in the valve body. This would lead to all sorts of nastiness all the way up to catastrophic failure. Nissan recently lost a large class-action targeting this transmission, as the only way to have prevented it was to have fluid changes far more aggressively than mandated by the manual… think 30k km for a transmission fluid change.
Tl;dr: there are other reasons for the shifting feeling… including actual shifting!
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