FWD: definition, features, and operating principle

FWD: definition, features, and operating principle

FWD is the general term for front-wheel drive. It was installed for the first time on the Alvis roadster in 1928. It became widely used in the 1960s and 1970s. Nowadays, it is most popular in mid-size and compact cars.

How FWD works

The key components of drivetrain in FWD cars (transaxle) are:

  • Gearbox: it is linked to the engine flywheel via a clutch or a hydraulic torque converter. It transmits torque from the engine to the final drive. It changes the gear ratio and this in turn helps to adjust the torque.
  • Final drive: it changes the gearbox output torque and transmits it to the differential.
  • Wheel differential: it distributes power between the front wheels. Often it is electronically locked and can be integrated into the gearbox casing.
  • Axle shafts: they transfer the torque from the differential to the wheels.

FWD types and features

Engine location FWD layout Advantages Disadvantages Cars with front-wheel drive
Longitudinal in front of the axle The engine, final drive, and gearbox are aligned one behind the other
  • High load on the drive wheels, which improves traction and road grip, especially on slippery surfaces.
  • Improved passive safety due to the increased crumple zone.
  • High steering wheel resistance.
  • Understeer.
  • Low off-road manoeuvrability.
  • Non-optimal brake force distribution.
Audi A4 B9, 80 В1, В2, 200 С2, 100 С2.   Volkswagen Passat B2, Jetta Mk2;
Renault 12, 18;
Alfa Romeo Arna.
Longitudinal behind the axle
  • Good off-road manoeuvrability due to short front overhang.
  • Long wheelbase provides a very smooth ride.
  • Insufficient load on the vehicle’s front part, which has negative consequences on its traction characteristics.
  • Limited interior space.
  • Low engine cooling system efficiency.
Citroën DS;
Renault 4, 5.
Longitudinal above the axle The engine is mounted above the transmission or on its side
  • Good visibility from the driver’s seat.
  • Optimal weight distribution.
  • Reduced engine efficiency.
  • Complicated drivetrain design.
Toyota Tercel L10;
Cadillac Eldorado;
Saab 99;
Oldsmobile Toronado.
Transverse in front of the axle The engine, final drive, and gearbox are aligned one behind each other
  • Compact layout
  • Simple engine design.
  • Uneven wear of the axle shafts.
  • Torque steer.
Volkswagen Caddy SAB, SAA, Bora 1J6, Golf BA5, BV5;
Opel Astra J, K;
Škoda Fabia 545.
Transverse above the axle
  • The gearbox shares a common casing with the engine, which saves space under the bonnet.
  • Complicated gearbox design, making  repairs more difficult.
Peugeot 104, 204, 304, 205;
Citroën Visa Super;
Rover Mini.

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