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Discussion Starter · #1 ·
Hi all, how safe is it to run the 4 mo haldex in permanent 4WD mode?. Using vag com and preforming the output tests on the haldex unit, you can enable the clutch(4WD) or disable it(2WD). is it safe to run permanetly enabled or disabled?
 

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I have no idea but it sounds interesting, do you know if it can be done and are just asking the implications or are you asking if it can be done?
 

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Discussion Starter · #4 ·
In vag com/ outputs tests you can lock the rear diff to make it permanent 4WD. I have done this yesterday. But I?m not sure whether this will damage the haldex in any way. For all of you with vag com and a haldex unit, go into AWD block and then perform the output tests, you will come across one that says haldex clutch engaged (I presume 4WD) and one saying clutch disengaged (I presume 2WD). This will only work as long as vag com is connected to the diag port, otherwise it reverts back to standard as and when mode.
 

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Output tests as are they sound, for 'testing' that switches and solenoids work when asked to save on time consuming wiring checks and should not be mistaken for anything else, for example if you do the same output test whilst in 'central electrics' on a polo or mk5 golf you can test the wipers the lights and the horn.

It is however only a test to make sure the system works when its asked and is not meant for permanent use, doing so may cause permanent/expensive damage.

If it looks like I repeated myself it was to make sure you read it

My advise is not too try it.
 

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Discussion Starter · #7 ·
Would this output test just lock the haldex clutch as it would when accelerating hard? or when the front wheel loose traction? How long can the haldex clutch stay engaged for? Does the longer the engaged clutch= more heat build up or something?
 

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The haldex coupling is operated as and when the car electronics decide, its usualy when there is either wheelspin or loss of grip, it is the ABS/ESP system that tells it when it is required and is not just as simple a system as you seem to think.

When you do the output test on 'any component' you are bypassing all the safety systems in place to protect it from damage, as it says its a TEST to show that it is working nothing else.

Like I said 1st time, my advice is not to try it
 

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I don't really see the point as you will get more transmission losses when going for it in a straight line or when you have good traction.
 

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I'd be careful, I think - if you have a good read around the www.haldex-traction.com site, there's much description about the Haldex being set up differently for different vehicles... Based on performance, handling, and longevity.

This kinda implies to me that the more often the Haldex is connected, and the more power is transferred, the more wear-and-tear.

Lots of people want their Haldex to transfer more power to the rear, and more often - which would probably give more fun handling. But Haldex seem to be saying they've programmed it not to, to keep the lifespan up?

Makes sense I guess - if it's always connected, and always building up heat through friction, then it'll never cool down and might sit there cooking itself [:D]
 

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Discussion Starter · #11 ·
So these new after market haldex ecu`s which give more rear bias, are they just wrecking the haldex, as as far as i know its just the ecu thats changed and not the internal workings of the haldex mechanics. I belive this ecu is in the region of ?1000 surly you can buy a new haldex for this?
 

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The Haldex uses a clutch;

If you lock the 4motion system into a 'permanent' 4 wheel drive mode then the transmission will try to turn both front and rear axles at the same speed, like a Land-Rover or similar with 'diff lock' engaged. Whilst this would be fine off road or in a straight line on tarmac, it would make going round corners very difficult, leading to heavy steering and worse understeer than a FWD Golf! It would also shred your tyres in no time, and if the grip was good then it would wear the Haldex clutch out, and it could even break your propshaft and/or driveshafts.

As Weelon suggests - it's not a good idea. If it was then VW wouldn't have bothered with a controllable 4wd system in the first place..........

Chris
 

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Discussion Starter · #14 ·
So can anyone explain what gains these uprated ecu modules give? They claim near 50/50 traction, by changing the ecu alone? how does this work? Will they wreck the laldex clutch?? why do they cost in the region of ?1000???????
 

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I honestly cant believe your still muttering on about it, if your so interested then shouldnt you go read up on it yourself instead of asking if anyone else has tried to blow their own one up after you suggesting it without full knowledge of what happens?

Im sure that other than for short term track/rally events that these 'uprated ecus' your on about are useless anyway! Maybe thats why they are so pricey?

When you do find out, from a reputable source, perhaps a company that sells them let everyone know, cheers ;)
 

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I saw the 600bhp R32 rolling road video where they had just the front wheels on the rollers......they used the 'disengage' mode I believe (ie 2WD).

I understand the intrigue into this possible override but as has been said, unless there's a good reason to do so, let the electronics sort it!

Perhaps the only real practical need would be on snow/ice/slippy mud?
 

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I saw the 600bhp R32 rolling road video where they had just the front wheels on the rollers......they used the 'disengage' mode I believe (ie 2WD).

They disconnected it by pulling the cable to the Pump and ECU. Even though it might be reliable to use "output tests" a serial-cable could fall out of the Laptop or WinXP crash. (not fun to suddenly get torque to the rear while on dyno)

This new Haldex controller has been used by Deamon on the VWvortex forum.

I've had that system in my car for 11.5 months and it is a great product. You might be able to get this product from www.nsracing.com , give them a call.

regarding topic:

On slippery surface it will work quite well with locked Haldex but with lots of grip it will put big stress on the shafts.

Inner rear wheel will try to slip while doing a U-turn, and while parking it feels like the car is halting, caused by lockup. (I've experienced it while testing various stuff in my car.)

I'll have to evaluate the "output test" on snow, if it works fine I don't have to bring spare ABS-sensors to two ICE-racing events in Januari. I had problem with one last week and don't want to risk being stuck with 2wd if another one gives up while at the event. (haldex disengages when a ABS sensor fail)

The Haldex upgrade is a completely different story, it shuts the valve before slip and keeps it closed for a while after throttle liftoff. It does not lockup when you don't want it to.
 

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Quote: posted by DanielT on 28/12/2004 14:17:39

I saw the 600bhp R32 rolling road video where they had just the front wheels on the rollers......they used the 'disengage' mode I believe (ie 2WD).

They disconnected it by pulling the cable to the Pump and ECU. Even though it might be reliable to use "output tests" a serial-cable could fall out of the Laptop or WinXP crash. (not fun to suddenly get torque to the rear while on dyno)

What....Windows XP crash???
 
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