The Haldex system was developed in the 1980s by Sigge Johansson, an engineer at SAAB. The concept was later sold to Haldex and first used by Volkswagen. The first generation of the Haldex system can be found in the Audi TT 8N, Audi A3 8L and Volkswagen Golf IV, among others. Volkswagen uses the commercial name “4Motion” for this system, while Audi uses the name “quattro”. Haldex has now developed five generations of the system, the latest of which is used in the latest version of the Audi TT. See the video for how it works and its history.
The first generation Haldex distributes the drive torque 90% to the front wheels and 10% to the rear wheels as standard. In the event of traction loss, an oil pressure-controlled clutch increases the torque to the rear wheels to a maximum of 50/50 distribution. The Torsen system, on the other hand, can vary the torque continuously, for example from 80/20 to 20/80, depending on the conditions.
Haldex versus Torsen: two different quattro systems at Audi
An important difference between the Haldex and Torsen systems is the method of drive. An Audi quattro with Haldex technology (such as the TT and A3) is basically front-wheel drive. Four-wheel drive is only engaged when necessary, for example in the event of loss of traction. This is in contrast to quattro models with the Torsen system (from the Audi A4 onwards), which have permanent four-wheel drive and distribute the drive torque flexibly between the front and rear axles.
Advantages of the Haldex system:
- Lower fuel consumption
- Lower weight
- Better weight distribution thanks to the rear-mounted Haldex unit
Disadvantages of the Haldex system:
- Not permanently four-wheel drive
- Requires regular maintenance (oil changes)
- Maximum 50% of torque to the rear wheels
Both systems therefore have their specific advantages and disadvantages, depending on the intended use and driving conditions. More about this in the video, including a nice visual comparison at the end.
If you really want to dive into it, you can go through the SSP206 Haldex self-study guide (search for “SSP 206 Audi pdf”). There are also many more videos online explaining how it works, how to maintain it and more.
© Header photo: Audi AG