Valve body pressure control system repair of TR-80SD (VW 0С8) automatic transmission.

The TR-80SD was developed by Aisin AW for the Volkswagen AG concern. In the VW notation system the gearbox received the designation 0C8. The eight-speed automatic transmission is designed for heavy vehicles with longitudinal engine arrangement, depending on the version it is capable of transmitting torque up to 1000 Nm. Since 2010, 0С8 is installed on diesel and hybrid Tuareg models and diesel Audi with engine capacity of 3.0 liters.

The mechanical part of the automatic transmission is controlled by an electrohydraulic valve unit. Besides shifting gears, the electrohydraulic unit regulates the oil pressure in the gearboxbox, control pressure in the valve body, the torque converter lock-up pressure and the lubricating pressure.

During operation, the valve channels and the solenoids of the valve body are worn out. One of the signs of wear is the drop in the main pressure of the automatic transmission. As a result of the pressure drop, the operation of the lubrication system and the torque converter lock-up system is disrupted. The consequence of such malfunctions can be an increase in the temperature of the automatic transmission, bumps and passing into an emergency mode.

To determine the operability of the solenoid, a special diagnostic stand is used.

Defective solenoids must be replaced. In some cases it is recommended to replace the solenoids kit.
To determine the defects of pressure control valves, the valve body is completely dismantled, cleaned and washed, then vacuum testing and external inspection of the valve channel are carried out.

Valve channels with signs of wear are being replaced by new channels manufactured by Maktrans.company specialists. The channels are made of high-strength aluminum and correspond to the parameters of the 0С8.valve body.

Examples of worn channel (bushing) of the valve - on the left, and a new channel made by the Maktrans.company specialists - on the right

The next stage is the installation of new valve channels into the valve body housing.

After replacing the solenoids and installing new channels of pressure control valves, the work of lubrication system and the torque converter lock-up system is normalized, the oil temperature of the automatic transmission is reduced. The valve channels made by the specialists of Maktrans company correspond to the performance of the valve body of the 0С8 automatic transmission. The service life of the manufactured valve channel corresponds to the service life of the original channel, at a much lower cost.

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