4 motion front to rear ratio

[AdamD]

It's a theoretical discussion of which I cannot claim any full understanding, let alone authority

Here is a more detailed explanation of the 'front wheels on ice' scenario

For the purposes of this discussion, the statement is wrong, and suggesting that a Haldex can (by design) send 100% torque to the rears is misleading. Let's not spread misinformation on the Internet - there's enough of that already.

That theoretical is discussing the nature of torque transfer and mechanical differentials, and their disposition to send more torque (in some cases 100%) to the output shaft with the least load. However, it's not about the ability of a Haldex AWD system to apportion torque across specific axles. If we want to apply the same semantics, a Haldex-equipped vehicle is 'mostly' 1-wheel drive (one of the two front wheels), and at other times usually 2WD (one front, one rear depending on the wheel on each axle with the greatest load).

Torque is a tricky thing to measure (just look at the huge complexities and variations involved when measuring it on a dyno), but when discussing any real-world operating condition - when all four wheels are touching the ground - a Haldex-equipped vehicle is essentially FWD, and at most sends 50% of engine torque to the rear axle (which means usually one wheel on that axle).

[dvkent]

Thanks everyone for contributing to this thread.
So it was a wet day today so on the way home from work I tried a hard(ish) launch from standstill and to my dismay was greeted with buckets of front wheel spin and axle tramp. Houston we have a problem! I did notice when I was doing this that the little 'traction control' light flicked on.
So I guess I am off to the VW specialist...

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[kamold]

For the purposes of this discussion, the statement is wrong, and suggesting that a Haldex can (by design) send 100% torque to the rears is misleading. Let's not spread misinformation on the Internet - there's enough of that already.

That theoretical is discussing the nature of torque transfer and mechanical differentials, and their disposition to send more torque (in some cases 100%) to the output shaft with the least load. However, it's not about the ability of a Haldex AWD system to apportion torque across specific axles. If we want to apply the same semantics, a Haldex-equipped vehicle is 'mostly' 1-wheel drive (one of the two front wheels), and at other times usually 2WD (one front, one rear depending on the wheel on each axle with the greatest load).

Torque is a tricky thing to measure (just look at the huge complexities and variations involved when measuring it on a dyno), but when discussing any real-world operating condition - when all four wheels are touching the ground - a Haldex-equipped vehicle is essentially FWD, and at most sends 50% of engine torque to the rear axle (which means usually one wheel on that axle).

Thanks for the clarification Adam, makes more sense to me now

dvkent please report back to the thread on the outcome as it's always good for anyone else who may have a similar issue to know what happens. Nothing worse than finding a thread which sounds like your issue only to have the poster disappear without reporting the resolution...

[AdamD]

Have a read of this thread dvkent:

Uh Oh, v6 passat without awd = balls

I wouldn't be surprised if this is the issue you're experiencing too.

[dvkent]

Thanks for the clarification Adam, makes more sense to me now

dvkent please report back to the thread on the outcome as it's always good for anyone else who may have a similar issue to know what happens. Nothing worse than finding a thread which sounds like your issue only to have the poster disappear without reporting the resolution...

Will do. I am taking it in on Tuesday for someone to check.

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[dvkent]

Had the CC looked at today and the diagnosis is (as suspected) the clutch pump in the Haldex. So the bank account will be $1100 lighter in the coming weeks.

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[3C4M Guy]

Alternatively have a read of VW's comprehensive Self-Study Programme number 206 at the link below. It's 44 pages of explanations on Haldex mechanicals, hydraulics and electrics.

http://www.volkspage.net/technik/ssp/ssp/SSP_206.pdf