Haldex Gen 2

[James I]

A call to all you technical guys, do you have a manual or exploded views of a Haldex GEN 2 set up, I am having a few issues with the Golf and I believe an understanding of the diff/Haldex arrangement needs some reading about before the socket set comes out.

Thanks

[DGW]

Do a Google search for 'SSP Haldex''. This will take you to a number of downloadable VW Self-Study Programmes (206 and 333) related to Haldex.

Another source would be erWIN. You could sign up for one hour or one day's paid access to original workshop info specifically for your car.

[James I]

Thanks Denis, I will have a look

[DGW]

I think SSP 78 is the one for your car but it is in German. The link to it and the other SSPs I mentioned are below.

http://www.volkspage.net/technik/ssp/ssp/SSP_78.PDF

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

http://vwpress.files.wordpress.com/2012/01/ssp_333_e.pdf

Good luck sorting your Golf's 4WD problems. BTW, have you done a VCDS scan to check for any Faults logged by the Haldex ECU?

[James I]

VCDS is going to be run tomorrow, I have had the software and lead for a couple of weeks now but only used it for re coding and general checks, it will be used in full anger on the Golf to see what is going on!

Thanks for all the info, I have downloaded and printed most of it off, other info I have found suggests to remove fuse 31 and see if there is a difference, with the symptoms the Golf is showing I think it will be mechanical rather than electrical, it is as though the whole system is locked driving all four wheels!

I will let you know what I find.

[TeflonTom]

What exactly are the symptoms you are getting with it?

[James I]

Car went for an MOT, when it went on the brake tester/rollers the car moved forward or backwards as drive was transmitted through the front wheels.

It is 4 wheel drive I hear you say, but the rollers they have are for 4 wheel drive cars, they work by turning one wheel forward and one backwards, therefore only moving the front wheels. However the issue we have makes the transmission "wind up" so something somewhere is not releasing or has seized.

Hence thinking it will be mechanical and not electrical or show as a fault on VCDS

[DGW]

I wonder what the outcome would have been had they tested the brakes on the road using a Tapley brake testing meter.

[James I]

No, Peter didn't take the car out as it was making a strange noise, I had to agree as the drive to the garage I thought it felt/sounded strange. Having never driven the car before I assumed it was normal.

Please bare in mind the car had been stood for 8 months, it has only done 50K miles and I only paid £300 for it.

When it was parked up it was running fine apart from a massive steering rack oil leak! I have replaced the rack for MOT, so now I will have to disconnect each part of the transmission until I find what is seized, then address that. I think this is a sensible way to start. obviously after VCDS as this might show something

[Huskoda]

It is 4 wheel drive I hear you say, but the rollers they have are for 4 wheel drive cars, they work by turning one wheel forward and one backwards, therefore only moving the front wheels. However the issue we have makes the transmission "wind up" so something somewhere is not releasing or has seized.

That would apply if the car has a center differential. From my understanding, Haldex equipped cars do not, the drive is sent to the front and rear axles simultaneously through a power take off alongside the front diff (though not applied without the haldex coupling being active). Spinning the front wheels in opposite directions would have zero effect on the rear axle, the haldex unit would still be getting full power.

There isn't a chance its had a racing haldex controller, is there?

[James I]

no chance at all, the guy who had the car only drove to wrk on a Monday and home on a Friday, he lived in the truck for the week. There is something stuck making the "wind up" issue, I will have to don the deer stalker and call my mate Watson to do some investigating.

Good news is I have Si at centralvwaudi on my team so we should be sort of ok lol...

[TeflonTom]

Having a centre dif makes no difference at all old huskies, because the wheels are being spun in opposite directions.

the haldex will engage at low speeds even if no wheel slip is present, except if the had brake is on, but that's dependant on an electric motor running and a series of pressure regulating valves being wound to the correct aperture size... i presume you've looked at the propshaft support bearing? It's a pig to get to up above the lower tunnel covers and exhaust system.

[James I]

Looked at nothing yet, tomorrow is the start of investigation, I am expecting the worst, that way if it turns out to be trivial or major I won't be disappointed lol

[Huskoda]

Having a centre dif makes no difference at all old huskies, because the wheels are being spun in opposite directions.

An open diff sends power to the point of least resistance. With a centre differential and the rear wheels parks on solid ground and the fronts on rollers, it will send it all to the front, where the front diff will sort it out. I looked at the linked documents and they confirm, at least for my Haldex 2, that the drive to the propshaft is taken from the crown gear for the front diff and is equally distributed to each axle at all times, barring interference from the Haldex coupling being disengaged. If it is trying to turn the front wheels, it therefore must be trying to turn the rear wheels an equal amount as there is no divider at the front of a Haldex equipped vehicle.

Regardless of what the front wheels or diff is doing, the propshaft will be rotating as it is directly mechanically linked to the output of the gearbox. This is completely different to a vehicle with a centre diff.

The same documents also however state that the car knows its on rollers so wont try and lock the coupling (though the propshaft will be spinning proportionally to the speed of the front wheels), so yes, the behaviour James is seeing is incorrect. Im curious, however, how it knows its on rollers and not, say, on ice as it seems to me that it may not try and move off on ice if it does this.

[James I]

The rollers we used counter rotate the front wheels so the prop shaft does not move. Wheels move as they would if you jack the car up and spin one side the other goes in reverse direction.

I didn't get to go to the garage today, but when I get a minute I will go across and do the VCDS check and then try and see why we have permanent four wheel drive.

As Huskoda says, there is no centre diff like a landrover, drive is sent down the prop at all times until the Haldex pressurises the clutch pack to transmit that drive through the rear diff and onto the wheels. By counter rotating the front wheels the prop shaft stays stationary, if both wheels were rotated in the same direction but with the handbrake on the ECU knows the rears are braked and will not lock the clutch pack on the rear diff, I don't think it knows it is on a rolling road, it is the handbrake signal that lets the ECU know, if you have a 4x4 with Haldex, pull the handbrake up one click until the dash light comes on and then you can spin up the front wheels with no drive to the rears.

[TeflonTom]

Oh James, yer something else I've thought of, is the abs light on? Sometimes if you have a failed abs sensor the haldex will stay permanently locked up.

[James I]

ABS light is on, I remember from a previous VCDS the week we changed the steering rack, good call Tom, thanks

[TeflonTom]

It's to do with the source that the haldex controller uses to determine the road speed, it compares the front and rear wheel sensors to calculate the percentage of wheel slip.. I ought to read the haldex workshop manual again tbh, I've forgotten most of it

[James I]

I hope it is that, a cheaper fix than some other possibilities.

[Huskoda]

Its just clicked for me, the rollers rotate the wheels, not the engine Derp.

[James I]

It turns out the rear diff has eaten itself, oil was drained today and what came out was more a metal paste than oil.