Aisin Automatics in Front-Wheel-Drive BMWs and Minis (UKL)

Since 2014 BMW has also built front-wheel-drive cars. The 2 Series Active Tourer came first; today the 1 Series F40, the 2 Series Gran Coupé F44, the X1 F48, the X2 F39 and the Mini generation from F56 onwards share the same base: the front-drive platform BMW internally calls UKL. With a transverse engine, the gearbox changes too. The ZF 8HP doesn't fit there. Instead, many models with an automatic use torque converter gearboxes from Aisin, alongside a dual-clutch gearbox from Getrag. This article explains which Aisin automatic sits where, how it differs from the 8HP and what matters after an engine tune.

Who is Aisin?

Aisin, formerly Aisin AW, belongs to the Toyota group and is one of the largest manufacturers of automatic gearboxes in the world. Aisin gearboxes are found in vehicles from Toyota and Lexus, Volvo, Peugeot and Citroën and many other brands. Their speciality is compact torque converter automatics for transverse installation. That is exactly what a platform needs where engine and gearbox sit side by side between the front wheels.

Three gearbox options in the UKL platform

If you drive a front-wheel-drive BMW or a current Mini, you have one of three gearbox types depending on engine, model year and equipment:

Gearbox	Type	typical for
six-speed manual	manual	base engines, depending on market
Aisin torque converter automatic (six or eight speeds)	converter, planetary sets	diesels, stronger petrols, M Performance models, early years also smaller petrols
Getrag seven-speed dual clutch	dual clutch	many three- and four-cylinder petrols from around 2018

BMW markets the Aisin eight-speed automatic as "Steptronic" or, in the sporty versions, "Steptronic Sport". It is fitted, for example, to the M135i xDrive (F40) and the X2 M35i (F39), as well as the diesel models with the B47 four-cylinder. The seven-speed dual-clutch gearbox has its own article: Getrag 7-speed DCT in the 1 Series, 2 Series and X1.

The same applies to Mini: early F55/F56 models came with an Aisin six-speed automatic; from the facelift, the dual clutch took over for many petrols, while diesels and stronger versions kept an Aisin torque converter automatic. The vehicle data for your VIN tell you which gearbox your car has; BMW marks Aisin gearboxes with "AW" in the gearbox designation.

How it differs from the 8HP

The Aisin automatics work on the same basic principle as the ZF 8HP: torque converter with lock-up clutch, planetary gear sets, hydraulically actuated multi-plate clutches and a transmission control unit, called the EGS at BMW. The differences lie in the surroundings:

• Transverse installation: the gearbox is more compact because there is little space between the wheels. Compact also means less fluid volume and less mass to buffer heat.
• Front-wheel drive and traction: in the lower gears, front-wheel traction already limits what reaches the road. Extra torque in first and second gear tends to create wheelspin rather than drive.
• xDrive with hang-on all-wheel drive: on the platform's xDrive models, the rear axle is engaged via a controlled multi-plate clutch. It has its own rating too, and more torque asks more of it.
• Drive shafts: with front-wheel drive, every load peak goes through the front drive shafts and joints, which also work at an angle when you pull away with the steering turned.

The Aisin automatic after tuning

In practice, the Aisin converter automatics in the UKL platform are forgiving when torque is delivered cleanly. The same ground rules apply as with any torque converter automatic: the transmission control calculates clutch pressures from the reported engine torque and knows an upper limit. How these relate is covered in Gearbox torque limits after an engine tune.

Three points matter most for the front-drive models:

1. Limit torque in the lower gears: a good calibration releases the extra torque mainly in the middle and upper gears. In first gear it achieves little and loads the gearbox, shafts and hang-on clutch.
2. Smooth torque build-up: a steep rise at low rpm is harder on the converter and clutch plates than an even plateau.
3. Keep an eye on temperature: compact gearboxes heat up faster under repeated full load. If you often drive hard or tow a trailer, don't treat the gearbox fluid as a lifetime fill. More in Automatic gearbox fluid change and tuning.

Typical symptoms in daily use

Most complaints we see with Aisin automatics in practice are about age and fluid, not a design flaw:

• Jerky downshifts in town, especially just before coming to a stop. Often the learned values and the fluid condition no longer match.
• Delayed engagement of D or R after a cold start. An early sign that the hydraulics or fluid need attention.
• Slight vibration at constant speed when the converter lock-up engages.
• High fluid temperature after a long climb or towing, sometimes with a temporarily changed shift strategy.

Some of this can be improved with fresh fluid and relearned adaptations; when that makes sense is covered in Resetting gearbox adaptations. If the symptoms persist, a thorough diagnosis is due before thinking about a tune.

Check before tuning

• Does the automatic shift cleanly when cold and warm, without jerks on downshifts?
• Is there a delay when engaging D or R?
• Are faults stored in the transmission control unit?
• Do you know when the gearbox fluid was last changed?

With a car of unclear history, an inspection at a specialist workshop is worthwhile. A tune does not repair a gearbox that is already struggling.

Process and transmission software

For front-wheel-drive BMWs, choose your model in the configurator, for example the X1 xDrive25i (F48). You order online, flash the engine software yourself via OBD and pay for the software only once it is finished. Whether an additional transmission software calibration makes sense and is feasible for your car is clarified on request; just mention your gearbox when ordering. Legally: the software change voids the vehicle's type approval, and the software functions are intended exclusively for motorsport. Details in the motorsport notice.

Conclusion

In BMW's and Mini's front-drive platform, Aisin torque converter automatics with six or eight speeds take on the role the ZF 8HP plays in the rear-wheel-drive cars. The basic principle is the same, the surroundings are not: transverse installation, compact design, front-wheel drive and hang-on all-wheel drive change where the limits are. If you limit torque in the lower gears, aim for a smooth build-up and look after the gearbox fluid, the Aisin automatic is a solid basis. More in the glossary under EGS.