CC:
Does the term constantly variable transmission scare you? It really shouldn’t. A CVT transmission shares a lot of components with a conventional automatic transmission. In fact, on that side, it’s probably a lot like it and a lot simpler too. Inside a CVT, well, you’re going to have a torque converter, you’re going to have planetary, so you’re also going to have clutches, and you’re also going to have large bearings inside the case, a pump, and a valve body. So these things can be serviced and diagnosed.
The main thing that scares a lot of technicians, well, it’s these two cogs. These two cogs, well, they changed the geometry between the two that changes the ratio of the gearbox with this chain. This chain, well, it’s kind of complex. There may be 300 or more different elements with these different links, and then two steel bands that hold them in place. It’s not that the bell itself slips, but it’s the geometry of some of the cogs that changes that causes some of these slipping complaints from your customers. So keep this in mind when you’re servicing one of these transmissions. It’s a lot about understanding these two and your base knowledge of automatic transmissions will work too.
But keep in mind, there are some critical differences. A CVT transmission has more than 700 PSI of force flowing through the valve body. Also, they’re going to have a cooler and maybe a little bit of a different filter arrangement that may look like a typical canister style filter. So servicing these, it’s critical to understand how these operate, and these require a lot of force. And also it requires a scan tool because the position of these cogs is monitored by the powertrain control module to make sure that they’re in the right place and they’re not slipping.
Typically on these, you’re going to have two position sensors, sort of like a crankshaft position sensor. It’s measuring the input and output and the speeds of the two and matching it up with what was selected and what was desired from the transmission. If it doesn’t see the data come out the right way, it’s going to set a code. Also, when you’re servicing one of these transmissions, make sure you’re going for the test drive and resetting the position and any relearns or adaptations for the transmission that you need to perform. I’m Andrew Markel. Thank you very much.
This video is sponsored by Auto Value and Bumper to Bumper
