I am considering moving back to Skoda with a Octavia 4x4. I beleive the newer cars are fitted with a improved version of theHaldex system (version 4?)

Can anyone clarify the improvements and when this new sysytem becan to be fitted to the cars.

Seems like a decent guide to Haldex clutches:

http://www.awd.ee/haldex.html

It's really difficult to find any info on which version is fitted to what though.

The latest Skoda 4x4s' use the Haldex 4th generation. It is very good and much has been said about it on the Yeti forum. Haldex have their own web site and is very informative and well worth reading.

Edited 20 January, 201016 yr by Anthony 1

IIRC Haldex 4 on facelift versions and Haldex 2 on pre-FL.

I honestly wouldn't get too hung up on it, both systems are well-regarded.

The essential difference between gen2 and gen4 is that gen4 will lock the clutch e.g. if you floor the throttle because it has a "pre-charge" system so that oil pressure is built up and can be applied to the clutch instantly. Whereas gen2 requires "slip" in order to generate the oil pressure needed to lock the clutch.

If you tend to have a heavy right foot and/or care about optimal acceleration then go for gen4, if you don't then I doubt you'll ever notice the "short comings" of gen2!

thanks all

I honestly wouldn't get too hung up on it, both systems are well-regarded.

The essential difference between gen2 and gen4 is that gen4 will lock the clutch e.g. if you floor the throttle because it has a "pre-charge" system so that oil pressure is built up and can be applied to the clutch instantly. Whereas gen2 requires "slip" in order to generate the oil pressure needed to lock the clutch.

If you tend to have a heavy right foot and/or care about optimal acceleration then go for gen4, if you don't then I doubt you'll ever notice the "short comings" of gen2!

just to further that, with the gen 2 as correctly pointed out you need slip to generate pressure to close the clutch where as with the newer gen 4 the ESP can also close it at will

functions of gen 4 over previous versions

1) Enhanced Vehicle Traction

* Torque transfer up to 2.400 Nm on prop shaft.

* Built-in torque transfer limitation.

* Full function in reverse.

* Instant activation independant of differential speed.

2) Enhanced Vehicle Dynamics

* Improved vehicle dynamics control during acceleration and deceleration.

* Rapid activation and deactivation.

* Fully controllable torque transfer characteristics.

3) Enhanced Safety

* Full integration with brake systems (like ABS) and stability systems (like ESP). On demand, the system can be deactivated in less than 60 ms.

* Limited/full AWD function with Run-flat-tyres.

4) Enhanced Vehicle System Compatibility

* Fully compatible with ABS, ESP and TCS without freewheel or additional clutch.

* On-line communication with the CAN system.

* No extra sensors needed. All required information obtained from CAN-system.

5) Enhanced Vehicle Driving Comfort and Transparency

* No wind-up during tight cornering and parking.

* Optimal traction during acceleration.

* No functional problems with tyres having uneven wear, pressure or size (minispare).

* Possible to tow vehicle with one axle lifted.

* Transparent actuation.

6) Enhanced Optimisation of Weight and Fuel Consumption

* The built in overload protection in combination with the fully controllable torque transfer characteristics,decreases the design requirements of the complete AWD drive line, resulting in reduced weight and reduced fuel consumption.

functions of gen 4 over previous versions

Are you sure that's over previous versions, because that just looks like a list of the general advantages of gen4, not over previous gens?

E.g. it states that it's fully compatible with ESP/TCS/etc... well, so is gen2! I also believe gen2 works in reverse without problem... I could go on :yes:

advanced and attractive features to the new generation of All-Wheel-Drive (AWD) vehicles.

Having read a nice long document on the Gen 4 and how its controlled and intergrates with the CAN Bus the only ones i would suggest that are features on previous Gens are

* On-line communication with the CAN system.

* No extra sensors needed. All required information obtained from CAN-system.

and im not sure about...

* No wind-up during tight cornering and parking.

* Possible to tow vehicle with one axle lifted.

but even those four are improved function over previous Gens

If you interested i'll see if i can find it again

Edited 23 January, 201016 yr by dan_the_v8man

I can say with confidence that the majority of that gen4 list was applicable to gen2 also. There are a few stand-out items that are specific to gen4, but no more than that.