If you have a small VAG '4wd' car; Whether it's a TT Quattro, an S3, a Golf 4motion, or an Octavia 4x4, the chances are your car uses the Haldex four wheel drive system.
Unlike traditional four wheel drive systems, this allows the vehicle to return similar fuel consumption to that of a front wheel drive when driving in a relaxed manner such as cruising along on the motorway, but with the grip of an all wheel drive car when it's needed!
In this blog, we will attempt to help readers better understand the Haldex system and it's service requirements.
What is the 'Haldex' part of the rear diff?
- What most people refer to as the Haldex is a coupling system attached to a traditional type rear differential that allows the rear drive to be brought in and out as it is needed.
- The system operates using a wet multi-plate clutch setup, somewhat similar to that of most motorcycles.
- The Haldex pump provides oil pressure, which actuates the clutches to bring in rear drive as and when the ECU requests it.
Why should I service this?
- Unlike differential oil, which lubricates; the Haldex oil is very specific and promotes friction between the faces of the multi-plate clutch setup.
- This friction between the plates causes particles of friction material to slowly build up within the oil.
- On most Haldex systems, a filter is installed which collects these unwanted particles, however in more modern models, the filter is omitted in favour of an oil strainer at the pump.
When should I service this?
- On vehicles with a Haldex Filter (Gen1 & Gen2) it is good practice to replace the oil and the filter at 20,000 mile intervals.
- On some vehicles where the Haldex system has a filter from factory, but the main dealers don't sell a replacement (Gen4) it is possible to purchase a filter from ourselves which can help increase the lifespan of the factory pump.
- On vehicles which don't have a filter (Gen5), we recommend servicing at 10,000 mile intervals, as the strainer on the pump can become blocked, eventually leading to pump failure. We always recommend removing the pump and cleaning the strainer as well as the housing whenever changing the Haldex oil on these models.
What about the front Haldex Diffs?
- Some Front wheel drive vehicles including the Golf GTI Mk7's with the Performance Pack and Leon Cupra Mk3 have a Haldex diff at the front of the vehicle.
- This 'VAQ' Haldex system actuates in the very same way as all of the four wheel drive Haldex systems, only it vectors the torque between the two front wheels increasing traction during performance driving conditions.
- These should be given the same service attention as the Gen5 four wheel drive models.
Can I use any oil in my Haldex System?
- No! You should ideally only ever use the Genuine VAG Haldex oil prescribed for your specific vehicle.
- The Haldex oil is a non-lubricative oil to promote friction of the clutch plates and using any other oil can result in a total loss of drive from the rear effectively converting your car into a front wheel drive.
What about the rear differential itself?
- If you have a Haldex four wheel drive car, it is good practice to replace the 'final drive' rear differential oil, as your rear diff has a completely separate oil bath to the 'Haldex' part of the four wheel drive system.
- VW/Audi have always quoted this as being a 'lifetime' fluid, however as a specialist looking after older cars - we recommend this is changed at intervals of around 75,000 miles.
Looking to book your car in with us for a Haldex Service?
- Follow the link here --> HALDEX SERVICING <-- to see pricing
- Feel free to call our workshop bookings team on 0161 776 0777 (option 1)
Blog post written by Al Brown @ Awesome