Hyundai/Kia introduced a Dual Clutch Transmission (DCT) or Automatically Shifted Manual Transmission (ASMT) in the 2012 Hyundai Veloster. The dry, dual clutch transmission was first mated to the 1.6 L turbocharged engine and then with other four-cylinder engines found in various Hyundai and Kia models.
The seven-speed DCT is like having two manual transmissions shifting together with two clutches. While one clutch and sub-transmission is engaged to the wheels, the other sub-transmission is selected and waiting to be shifted. The DCT is shifted with electric motors that move the shift forks. One actuator controls the odd gears, while the other actuator controls the even gears and reverse. Another set of actuators engage and release the dual clutches.
When there are issues with the actuators, the transmission will slip and have harsh shifts.
The DCT transmission does not have a parking pawl, like an automatic transmission. The electric parking brake works with the transmission when it needs to be held in position on a hill or parked with the engine off.
Protection Modes
The DCT transmission manages the temperatures of the clutches. It determines the temperature of the clutches by detecting the amount of clutch slipping. If the driver is holding the car on an incline with the gas and not the brake, it will increase the temperature of the clutches. Also, heavy stop-and-go traffic for prolonged periods will cause the clutches to overheat.
If the clutches are getting hot, the LCD screen in the instrument cluster will instruct the driver to press the brake pedal when the vehicle is on a slope that is 5% or higher. The car might shudder after one or two seconds to alert the driver.
If higher temperatures are detected, the transmission control unit has four stages of protection. The 1st, 2nd and 3rd stages display a message that the “temperature is too high” and the driver needs to pull over. Also, only one clutch is used. The 4th stage alerts the driver and the vehicle stops for 20 minutes. The clutches will open, and the vehicle can’t move.
Diagnostics
If there is an issue with a clutch or gear actuator, you will observe the problem is either in the odd or even gears only. If a car has high miles or has lived a hard life, clutch engagement bearings and forks can wear and change how the clutches catch.
The system monitors the condition of the clutches with speed sensors on the crankshaft and sensors on the odd and even shafts. The actuators for the clutches and gears have position sensors that can fail. If the sensors are giving incorrect information, the shifts can be inconsistent and set codes. If an actuator is replaced, the position of the actuator must be relearned with a scan tool.
Maintenance
These DCTs use 70W GL4 gear oil (2012-‘14 Velosters use 75W/80 GL4). There is no service interval for the lubricant and it is considered maintenance-free. But, the fluid must be inspected and replenished every four years or 40,000 miles.
