Hyundai has been quite forthcoming with providing technical data for its 6-speed transmission (Figure 1) — much of which is required should the need arise to diagnose one of them. This transmission is used in both Hyundai and Kia vehicles as far back as 2009 here in the United States.
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On the transmission there is a tag riveted to the case with the vehicle identification number on it. Alongside this tag, etched into the case, is a transmission number (Figure 2). For a guide to all the versions of this tranmission, and what the different VINs signify, visit www.motorage.com/hyundaitrans.
With a quick look at the cutaway of this transmission in Figure 3, you can see that this 6-speed is a compact unit. It uses a triple planetary setup with a low one-way clutch device, two driving clutches and three brake clutches. Put this together with the component application chart shown in Figure 4, along with the solenoid application chart in Figure 5, and you yourself have quite a bit of information to do a considerable amount of diagnostics.
One of the first things I like to look for in a clutch and brake component application chart is not just what is on and off for each gear, but which shifts are synchronous and non-synchronous.
Let’s begin with taking a look at first gear. You will notice that the Low/Reverse (L/R) clutch is applied as indicated by the solid circle. The same is true with the Underdrive (UD) clutch and the one-way-clutch device. You will also notice that with the L/R clutch there is an arrow to the left pointing to an “X,” while the opposite is seen with the low one-way-clutch (OWC) device.
What this tells us is that the L/R clutch will be released before the shift into second takes place. When it does, the OWC device will hold stationary the same part of the planetary system the clutch was holding. In short, when the L/R clutch is applied, the low OWC device is ineffective until the L/R clutch is released. This OWC will need to hold until a shift into second takes place. The UD clutch remains applied so all that needs to take place is to add the 2/6 clutch to make the 1-2 up-shift. The OWC simply freewheels at this point and is no longer a part of the powerflow. This system makes the 1-2 up-shift and the 2-1 downshift a non-synchronous shift.