Automatic and modern gearbox repair

Most automatics are built by a handful of manufacturers and fitted across dozens of badges. A Volvo, a Ford, a Peugeot and a Land Rover can all be running the same Aisin unit. Once you know which family you’ve got, everything about the diagnosis and the repair follows from that.

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Shared across both brands and split into dry-clutch and wet-clutch families. Dry units, the 6DCT250 and the D7UF1 seven-speed in the i30, Ceed, Kona and Stonic, judder at low speed and wear their clutches, often with a clutch overheat warning after stop-start driving. Wet units, the D7GF1 in the Tucson, Sportage and i30 N and the D8LF1 eight-speed, suffer more from fluid degradation and hydraulic control faults.

These boxes are unusually sensitive to software. Hyundai and Kia have revised the control strategy repeatedly, and a car on old calibration can feel significantly worse than the same car brought up to date. We check that before quoting for anything mechanical.

Common faults: judder pulling away, clutch overheat warning and temporary loss of drive, harsh shifts from actuator motor wear, clutch actuator fork wear, dual mass flywheel rattle at idle, slipping on wet units from degraded fluid.

Most full hybrids don’t have a gearbox in the conventional sense. A Toyota or Lexus e-CVT is a planetary power-split device with two electric machines in one housing. No clutches, no torque converter, no shifting. Very reliable, and when it does fail it’s usually a bearing, a seal or the fluid.

The classic fault is a rising whine that tracks road speed, worst at 40 to 60 mph, usually the motor-generator bearings. Caught early it’s a bearing job. Left alone, the debris circulates and takes the rest with it.

The other thing nobody does is change the fluid. Toyota list the transaxle fluid as long-life. The fluid itself doesn’t know that, and at 100,000 miles it’s dark. A drain and fill is inexpensive and the best thing you can do for one of these.

Families covered: Toyota and Lexus e-CVT (P111, P112, P310, P410, P510, P610), Honda i-MMD, Ford HF35 and HF45, VW DQ400e, ZF 8HP hybrid, Mercedes 725.0 hybrid.

Work on high-voltage systems requires the appropriate qualification and isolation procedure.

722.6, 722.9 and 725.0 conductor plate and valve body work. Aisin TF-80SC and AWF8 solenoid packs and valve bodies, a very high-volume family across Volvo, Ford, Peugeot, Citroën and Land Rover. BMW GS7D36SG dual-clutch mechatronic and clutch pack work for the M3, M4, 135i and 335i.

Full rebuild. Mechatronic and valve body remanufacture. Torque converter rebuild and balancing. Solenoid and sensor replacement. TCU programming, cloning and adaptation. Fluid and filter service to the correct specification and fill temperature. Cooler flushing. Diagnostics and road test.

There’s a myth that modern automatics are sealed for life. They aren’t. The fluid degrades, and on some units a service at the right interval genuinely prevents failure. But once a box is already slipping or juddering, a fluid change can make it worse, because fresh fluid dislodges debris that was doing a job. We’ll tell you honestly which side of that line your gearbox is on.