Haldex drive train efficiencies

[Gress]

Hey there, been researching quite a bit on what my next project car will be. It's down to the Audi A3/A4/A6/TT, Subie 2000 2.0/2008 2.0 hatch or a Golf mk4 4Motion.

Half of those cars listed are real AWD such as the subie and the Audi Quattros but the other half like the golf, TT and A3 are Haldex systems. I understand that how well the haldex systems work differ from car to car and depending on what generation the haldex system is, but could I get some information as to how good they are in general, compared to a true AWD system?

Having a smaller Golf or S3 would be nicer that having to buy a larger true AWD car as well as the fuel economy being better and tire use too, but at the same time, I've seen how the 2001 TT works in the snow and the haldex system doesn't seem all that useful to be truthful.

If the haldex systems aren't all that great for maintaining grip when at the limit due to how slow the system reacts, is there anyway to manually lock the system's clutch to be fully engaged on demand so that it would effectively act as a true AWD all the time?

Any info on these things would be greatly appreciated, thanks in advance.

TLDR; How good are the haldex systems and if they're sup-par, can I manually set them to permanent AWD some way?

Edited by Gress on Thursday 27th December 14:55

[thetrickcyclist]

Some people would look at Haldex then remember previous VW emission scandals

It's a bit like saying EDL on a FWD makes it equal to quattro with torsen.

[mercedeslimos]

You can by a controller to vary torque split. Also a quaife or wavetrac at both ends makes a huge difference

[Mikey G]

If I was to compare my old 2000 mk4 Golf 4 motion with my older later 2008 S3 8P then the later system was more refined. The S3 was more controllable in a slide in the wet where as the older Golf would snatch and release making the rear a bit difficult to predict on the edge.
Obviously tires make a difference and the fact Golf was V6 as opposed to Turbo in the S3 made power delivery different so you would have expected the Turbo car to be the snatchy one but it was the Golf that had the unpredictable handling. Think the S3 was another generation haldex compared to the MK4.

[mercedeslimos]

Mikey G said:

If I was to compare my old 2000 mk4 Golf 4 motion with my older later 2008 S3 8P then the later system was more refined. The S3 was more controllable in a slide in the wet where as the older Golf would snatch and release making the rear a bit difficult to predict on the edge.
Obviously tires make a difference and the fact Golf was V6 as opposed to Turbo in the S3 made power delivery different so you would have expected the Turbo car to be the snatchy one but it was the Golf that had the unpredictable handling. Think the S3 was another generation haldex compared to the MK4.

The Mk4 uses gen 1 haldex, the MK5 platform cars use gen 2 which always have a minimum of 10% torque going to the rear wheels. I'm mid way through a retrofit of the latter system

[thetrickcyclist]

mercedeslimos said:

Mikey G said:

If I was to compare my old 2000 mk4 Golf 4 motion with my older later 2008 S3 8P then the later system was more refined. The S3 was more controllable in a slide in the wet where as the older Golf would snatch and release making the rear a bit difficult to predict on the edge.
Obviously tires make a difference and the fact Golf was V6 as opposed to Turbo in the S3 made power delivery different so you would have expected the Turbo car to be the snatchy one but it was the Golf that had the unpredictable handling. Think the S3 was another generation haldex compared to the MK4.

The Mk4 uses gen 1 haldex, the MK5 platform cars use gen 2 which always have a minimum of 10% torque going to the rear wheels. I'm mid way through a retrofit of the latter system

I think you are completly missing the point.
10% of 0 =0

[mercedeslimos]

thetrickcyclist said:

I think you are completly missing the point.
10% of 0 =0

not going to argue with the SSP that techs get. that 10% is if you are applying throttle, naturally. But it is all the time, unlike the previous generation which would only engage when it detected slip in the front axle, whereas gen 2 has 10-50% available upon slip, and 10% all the time to aid traction in normal driving.

[Mikey G]

mercedeslimos said:

thetrickcyclist said:

I think you are completly missing the point.
10% of 0 =0

not going to argue with the SSP that techs get. that 10% is if you are applying throttle, naturally. But it is all the time, unlike the previous generation which would only engage when it detected slip in the front axle, whereas gen 2 has 10-50% available upon slip, and 10% all the time to aid traction in normal driving.

I'm not an expert on the Haldex but I think what you are saying is the same as what I have read before, Gen 1 uses the difference in speed between propshaft and rear differential to 'pump up' the haldex clutch to apply power to the rear. Gen 2 has an actual pump that runs all the time which controls the clutch even at stand still so when you mash the throttle to the floor it doesnt need to detect front wheel slip.