HKS GR Corolla Transfer Case Oil Cooler Kit

To avoid AWD disengage with track use, this will need to be paired with a Syvecs AWD controller. 

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Monitors and controls transfer oil temperature during high-load continuous driving to protect the transfer unit.

• On the GR Corolla, the transfer system switches to 2WD during continuous high-load driving to prevent overheating.
• The HKS TRANSFER OIL COOLER helps maintain lower transfer case oil temperatures, extends oil life, and protects the transfer unit.
• For vehicles equipped with the Transfer Protection Cancel Program, full-time 4WD is available even during circuit driving by disabling the limp mode, which switches to 2WD. *(Using the cancel program may void the vehicle’s warranty. Please check your warranty terms.)

Components

• Transfer cooler pipe
• Oil filter
• Oil pump
• Oil pump controller
• Mounting bracket
• Hoses, harness, and hardware set

■Features

• The dedicated pipe-type cooler ensures the transfer oil is cooled without affecting engine coolant, engine oil, or I/C cooling performance. The bracket fixing the cooler is designed to avoid obstructing airflow to the radiator and intercooler.
• HKS uses a high-load, high-flow electric oil pump, controlled by a dedicated pump controller. If the pump is operated when the oil temperature is low (high viscosity), the overcurrent protection control puts it in standby mode and automatically restarts once the oil temperature reaches an appropriate level. It’s recommended to operate the pump when the oil temperature is above 60°C to prevent overloading.
• For vehicles equipped with a transfer protection control cancellation program, selecting the TRACK mode within 1 minute of engine startup automatically activates the pump. The pump's operating status can be checked on the controller display. The kit includes wiring from the power source to the electric pump.
• The transfer oil outlet uses a specially designed banjo-type attachment that is resistant to impact damage. The banjo bolt has a PT1/8 plug hole, allowing for oil changes without removing the bolt, and can also be used as a temperature sensor mounting hole.

• This product is designed for circuit use where transfer oil temperatures can rise significantly. For daily driving where transfer oil isn’t heavily loaded, please keep the pump turned off.
• Even on track, avoid operating the pump when the oil temperature is still low, as this can put excessive load on the pump and piping. Use it only when oil temps are around 60°C or higher.
  If using AUTO or FULL AUTO mode and the pump frequently starts and stops, it means the oil temperature is too low. In such cases, avoid long-term use to prevent damage.
• Please use stock transfer oil or HKS G900 75W-90 gear oil. Do not use oil thicker than 75W-90, as they can overload the system.
• The transfer protection control cancellation function only works on vehicles equipped with the appropriate program. If your vehicle doesn’t have this program, do not connect the “4WD mode select switch” connector — doing so will disable 4WD.
• Some vehicle modifications are required for installation:
  • May also require trimming of bumper reinforcement, intercooler air guide, and undercover duct.

■Driving test data of GR Corolla at Fuji Speedway Racing Course

• The stock oem test was terminated when the oil temperature increased to approximately 150°C, although the oil temperature is still rising without the transfer oil cooler installed.
• The test with the HKS Oil Cooler kit was terminated when the oil temperature rise settled at around 125°C with the transfer oil cooler installed.
• Based on these results, estimating the temperature at which the oil temperature becomes stable after further laps, the temperature difference with and without the transfer oil cooler is expected to reach about 80°C.　With the transfer oil cooler installed, the oil temperature can be stabilized at about 130°C even after continuous driving.

*The above information is based on HKS in-house testing.

Vehicles after April 2025 are available for the transfer protection control cancel function. For other vehicles, the transfer protection control cancel function is not available.
Wiring and operation of the pump controller differ depending on if the vehicle has the cancel program.

• Compatible with "MORIZO Edition".
• Compatible with all 2023 and 2024 GR Corollas
• Compatible with 2025 facelift models
• Professional Installation recommended