# effing haldex AWD system!!!!



## VWdriver03 (Jul 26, 2005)

I'm not sure how many of you have had serious issues with the haldex diff. itself(not the controller). but me and my neighbor seem to be having the same problem and were thinking its the haldex. its not stuck in FWD like some people have had happen, but it seems to be binding under slow sharp turns. 
Like if I'm making a sharp turn out of a parking space you can feel this thunk...thunk...thunk steady and constant, you can count 1 mississippi.. thunk, 2 mississippi.. thunk, 3 mississippi.. thunk. feels like I'm running over those road reflectors but really close together. and I've had one issue of while turning sharply into a parking space it feels like one of the back wheels is dragging, and my neighbor has had that happen to him quite often.
I checked out the front suspension and steering components and they seem to be fine from what I can tell. I don't know, maybe these $hitty haldex systems have a short life


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## heinzboy57 (Oct 7, 2007)

*Re: effing haldex AWD system!!!! (VWdriver03)*

whens the last time you changed your fluid/filter?
i changed mine out recently (bought the car late last year) and not too much fluid came out when i drained it. of course i spilled a bit while trying to fill it...so i'll prolly be doing a fluid change again in spring...


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## cdougyfresh (Sep 16, 2004)

*Re: effing haldex AWD system!!!! (heinzboy57)*

hmm.. my sister's outback does the same thing....


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (cdougyfresh)*

well i just went to pick up some food and things got a lot worse, its not making a thunk sound, but more of a actual binding soynd like metal pushing on metal and its doing it every time I move from a stop, turning or going straight. its hard to pick up if its comming from the front or back, kinda seems like both(maybe the feeling is traveling through the driveshaft)
and yeh the car is due for a haldex fluid change at 80k and has 78k on it now. if that whole haldex system goes out, its game over for me, no more TT


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## exboy99 (May 14, 2002)

*Re: effing haldex AWD system!!!! (VWdriver03)*

the sounds you describe....
I'd get it serviced NOW
jack up the rear end
and get busy looking things over
maybe there's something obvious?


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (exboy99)*

I was just under there last weekend when I changed the rear diff. fluid and saw nothing unusual... I have a habbit of checking things out when I'm under the car just to make sure nothings wrong. like today I decided to inspect the cv boots while under there and sure enough one was ripped


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## PhunkFX (Feb 22, 2002)

*Re: effing haldex AWD system!!!! (VWdriver03)*

Woo... I'd rather change and axle or cv joint than the haldex mechanics!


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (PhunkFX)*

yeh and fortunately it was small enough that I could patch it. I guess the car's got to go to the dealer monday, see what they can find out. normally I'd tear into it myself but where I'm living now leaves me no place to work on the car. there's already several issues with the car now and if that whole haldex unit is on the way out, it might be goodbye


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## Morio (Feb 16, 1999)

*Re: effing haldex AWD system!!!! (VWdriver03)*

good luck man... I hope it's just the CV


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## v3rtig0 (Feb 3, 2008)

*Re: effing haldex AWD system!!!! (VWdriver03)*

that bites...i on the other hand, today, went to have a used car check done by audi here in richmond and they said there was an error that was reading in their diagnostic about the haldex...the price quote they told me was $1880 to fix whatever was broken...didn't know what to think since i'm new to the haldex and was gonna read around here to see if there was a discussion about it. i'm still planning to get the haldex serviced since it's time and the previous owner hadn't done so or at least there was no record of it via the vin # only the service records http://****************.com/smile/emthdown.gif


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (v3rtig0)*

yikes thats not good, I have always had my haldex serviced at the 20k mile intervals, so neglect should not be a factor with my car.


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## DnA-TT (Oct 21, 2003)

*Re: effing haldex AWD system!!!! (Morio)*

Yeah, sounds more like a CV issue than a center diff issue...of course I'm new to the Haldex, too. 
Get the CV boot fixed, see if your troubles go away. One thing at a time.


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## heinzboy57 (Oct 7, 2007)

*Re: effing haldex AWD system!!!! (DnA-TT)*

if it is the actual haldex mechanical unit/diff, is the only used option from the TT quattro and/or R32?..are there any other cars out there that use the same unit that you might find from a junkyard?


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (heinzboy57)*


_Quote, originally posted by *heinzboy57* »_if it is the actual haldex mechanical unit/diff, is the only used option from the TT quattro and/or R32?..are there any other cars out there that use the same unit that you might find from a junkyard?

a S3 if you live in mexico








and as easy as it would be, its not the cv. it was only a tiny rip less than a inch long and almost completely on the shaft itself, only a tiny drop of grease had started to come out. 
the feeling is comming from the driveshaft, I'm positive.
I hate to drive the car like this but I have to


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## ViolatorDM (Jun 19, 2008)

*Re: effing haldex AWD system!!!! (VWdriver03)*

Hello there,
I know your last post is waaaay old but it's worth the shot...
I'm having the same issues I think with my Haldex Unit after I installed a Haldex Gen1 Competition Controller from HPA and also performed a Haldex Maintenance (OIL & Filter etc) along with the installation. Now, I can feel the same thing that you felt coming from the back of the car, everytime I turn my steering wheel dead-left/right and try to move the car. I also feel the same thing on sharp turns doing up to 10km/h - 20km/h. I also noticed that either the rear left or right wheel will *lock*-*unlock* during this...
Were you able to find what caused the problem at your car? Where you able to fix it somehow?
Dimitris


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## VWdriver03 (Jul 26, 2005)

*Re: effing haldex AWD system!!!! (ViolatorDM)*

I was actually having 2 issues. the metal scraping sound was my downpipe had come loose and was hitting my drive shaft. I never actually fixed the other issue(the one you're having), I traded the car for my S4 about a month after that post.
BUT... from my recent problem with my Audi 90 it seems like its related to the rear diff staying locked. If you're hearing a rear wheel drag/bind under slow sharp turns it is most likely because you EDL/haldex has locked your rear diff(for whatever reason). when the rear diff is locked you're rear wheels are being forced to turn at a similar rate therefore one will drag if the other is spinning slower than it is. since the TT has a haldex system it adds to the problem of finding out why the rear diff is being locked. it should only be locked at slow speeds when there is a significant amount of traction lost in the rear axle or there is a lot of power being sent to the rear.
My best guess is that your new haldex controller is sending power to the rear even at slow speeds, therefore you're EDL/haldex is locking the rear diff to keep you from breaking traction. this all makes sense if you have the "red" haldex controller, the "blue" controller is supposed to keep the rear diff unlocked at slow speeds. so in you're situation I wouldn't worry about anything but on a side note, be careful driving in poor conditions with that competition controller on the street, the handling is alot different and possibly dangerous if you're not used to it.


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## ViolatorDM (Jun 19, 2008)

*Re: effing haldex AWD system!!!! (VWdriver03)*

Hello again and thank you much for your reply and IM http://****************.com/smile/emthup.gif 
I gave HPA a call yesterday to let them know of the issue I'm experiencing and they told me that neither the Blur nor the Competition (Stealth or Orange) Controllers are supposed to "act" like this.
As a matter of fact they recommended I performed a thorough cleaning on the Competition Stealth Controller I have and see how it goes. Not only have I cleaned they Controller but I also performed yet another Haldex Oil change.
Nevertheless I'm still experiencing the same issue. Suffice to say that there are absolutely no errors reported by neither the Diagnostics System that my authorized Service/Workshop/Reseller is using nor by a VAG-COM Cable I have hooked up onto a laptop.
This is so frustrating and I have absolutely no clue what to do next. For sure I'll let HPA know that the issue still remains. My next step would be to put the original controller I had back on the car and take the Competition Controller and install it in another car to see what happens and take it from there.
Dimitris


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## Minibabe (Jul 5, 2006)

*Re: effing haldex AWD system!!!! (ViolatorDM)*

I had this happen to me....changed a bunch of things and the problem was not the haldex controller it ended up being the diff. I had blown up the rear diff of the car and exactally what you are describing is what happened to me.
changing the fluid did not help. The way to check to see that it is not the controller is to preform the haldex test. That is how I ruled out that it was not the controller and it was the actual rear diff.
I picked one up on the cheap and I am going to be swapping out my broken one with a peloquin sometime next year so I dont have to worry about this again. I did the entire job in a day....it was really easy to replace the diff. 
If you have any questions feel free to respond back here or PM me http://****************.com/smile/emthup.gif


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## SteveCJr (Aug 3, 2008)

IIRC, I remember someone posting a problem like this a while back. Turned out to be a faulty wheel speed sensor.


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## raidendb (Jul 25, 2008)

if the sound is coming from the front then it might be the cv shaft...if its from the rear sad to say it may be the differential locking during the turn. i'll try putting everything back to stock and see how it goes. it just might be your controller.


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## BluHeaven (Jun 7, 2003)

*Re: effing haldex AWD system!!!! (ViolatorDM)*

I just fixed this issue... in my car it was a shot controller. The valve that controls the haldex pump gets stuck and the haldex has the rear locked all the time. I had no codes either. So it's probably a bad or clogged valve in the controller, or it's the pump itself.
Hook up the VAG and do the output tests for the haldex. It will lock and unlock the haldex, turn the pump on and then off. Listen and make sure the pump comes on and stays on until you click 'next' to turn the pump off. 

If your stock controller is still good then the problem should go away and you'll need to send the orange controller back to HPA. Either the unit was already bad or dirt or something got into the valve during the install. Make sure the gasket didn't slip and block the holes for the pump.
If it still does it with a good OEM controller then I'd look at the pump itself. It is replaceable without buying an entire new haldex. I'd have a shop look at that one.

_Quote, originally posted by *ViolatorDM* »_Hello there,
I know your last post is waaaay old but it's worth the shot...
I'm having the same issues I think with my Haldex Unit after I installed a Haldex Gen1 Competition Controller from HPA and also performed a Haldex Maintenance (OIL & Filter etc) along with the installation. Now, I can feel the same thing that you felt coming from the back of the car, everytime I turn my steering wheel dead-left/right and try to move the car. I also feel the same thing on sharp turns doing up to 10km/h - 20km/h. I also noticed that either the rear left or right wheel will *lock*-*unlock* during this...
Were you able to find what caused the problem at your car? Where you able to fix it somehow?
Dimitris


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## Neal98 (Apr 3, 2013)

*Help!*

I know this thread is older then dirt, but, I am having the same problem. My Audi mk1 TT is stuck in 4wd, and will not release. turning right or left, you can here the tires grabbing and hear and feel the popping from the back, unplug the haldex controler, and car behaves normal. have replaced 2 haldex controls and the complete rear end, all to no avail. It seems the computer is requesting the haldex to lock up, but I have no idea why. Anybody else run into this?


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## sciroccohal (May 4, 2005)

*how many miles.*



VWdriver03 said:


> I'm not sure how many of you have had serious issues with the haldex diff. itself(not the controller). but me and my neighbor seem to be having the same problem and were thinking its the haldex. its not stuck in FWD like some people have had happen, but it seems to be binding under slow sharp turns.
> Like if I'm making a sharp turn out of a parking space you can feel this thunk...thunk...thunk steady and constant, you can count 1 mississippi.. thunk, 2 mississippi.. thunk, 3 mississippi.. thunk. feels like I'm running over those road reflectors but really close together. and I've had one issue of while turning sharply into a parking space it feels like one of the back wheels is dragging, and my neighbor has had that happen to him quite often.
> I checked out the front suspension and steering components and they seem to be fine from what I can tell. I don't know, maybe these $hitty haldex systems have a short life


How many miles and where is the car located?
My 'order of blame' normally goes like this.
Miles,
Maintenance or lack therof.
Environment
Abuse
THEN I blame the engineering. Of course HALDEX is used on two dozen premium manufacturers of fine automobiles and is the premier manufacturer of AWD systems....so my first reaction is to always BLAME the manufacturers and then the engineers...

Blame sure gets things fixed quicker than FACTS......nope!

My TTQ is only 14 years old...so what do I know.


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## Neal98 (Apr 3, 2013)

car Is located in NC at this time, but spent it's life in Las veges and in LA mileage is 107,000 and rear end and haldax unit were serviced about 4 times in the last 4 months (everytime I changed the controler or rear end)


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## 1fast2liter (Apr 4, 2005)

Neal98 said:


> I know this thread is older then dirt, but, I am having the same problem. My Audi mk1 TT is stuck in 4wd, and will not release. turning right or left, you can here the tires grabbing and hear and feel the popping from the back, unplug the haldex controler, and car behaves normal. have replaced 2 haldex controls and the complete rear end, all to no avail. It seems the computer is requesting the haldex to lock up, but I have no idea why. Anybody else run into this?



spoilers like that make baby jesus cry:banghead:


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## lite1979 (Sep 9, 2005)

Have you scanned with VAG-COM to check for fault codes?

Since the OP of this thread never marked his issue as solved, I would start a new thread with a long detailed description of how the car drives so we can focus on your problem without sifting through the four-year-old posts that led nowhere in this one...


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## 18T_BT (Sep 15, 2005)

1fast2liter said:


> spoilers like that make baby jesus cry:banghead:














That actually looks like an APR wing which is a very nice carbon fiber piece. If this car is used at speed and especially on a road course, that wing is extremely functional :thumbup:


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## 1fast2liter (Apr 4, 2005)

Still ruins the look in my eyes

Sent from my SCH-R950 using Tapatalk 2


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## becker780 (Apr 30, 2013)

This threads pretty old but i have the same problem. My 01 225 is stuck in 4x4 and Im worried that the rear dif is shot. I think its been replaced. Im goin to try a fluid change but doubt it will fix it. Im also going to unplug the controller and see if it goes away. 

The next step is to see if theres anyone in the area that knows how to test outputs with a vag


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## Neal98 (Apr 3, 2013)

I bought software from ross-tec to see if I could diag the locked 4x4 issue. seems I can command the pump off and problem goes away, but in normal driving, the pump is on HI all the time....even standing still. the brakes or the parking brake will not knock the pump off, its just stuck in HI all the time. all wheel speeds are the same and steering angle is within range....I'm at a loss


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## becker780 (Apr 30, 2013)

That seems exactly like my problem.


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## Neal98 (Apr 3, 2013)

becker780 said:


> That seems exactly like my problem.


 I have read countless threads all over the web about this exact problem, but I never see a solution! Today I changed my controler (again) with a brand new one, and the pre-charge pump with a known good one....same thing, stuck in high all the time. WTF!!!! no ABS codes, all wheelspeeds reading correctly, no codes of any kind show up! Tommorow, I'm going to go over every wire, inch by inch, but I already know I wont find anything,


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## [email protected] (May 14, 2009)

I have been looking into this issue for a while. I have not confirmed yet by taking apart my Haldex, but I believe the dis-engagement is helped by the vacuum line running off the rear end. The line disappears up into the floor, I have not pulled the fender liner/rear trunk apart to see where it goes.


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## Neal98 (Apr 3, 2013)

[email protected] said:


> I have been looking into this issue for a while. I have not confirmed yet by taking apart my Haldex, but I believe the dis-engagement is helped by the vacuum line running off the rear end. The line disappears up into the floor, I have not pulled the fender liner/rear trunk apart to see where it goes.


 Is that not just a vent hose to bleed off pressure as the diff heats up? Anyway, I'm not convinced that's the issue, as my pump is being commanded to high by the haldex controller. I can use vag-com and command the pump to low, eveythong works fine, but the second you take it out of diag mode....right back to high. somthing is telling the controller it needs full haldex pressure, even sitting still! God I would SO love it if you were right though! The car is almost un driveable like this!


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## becker780 (Apr 30, 2013)

I dont understand why it would need a vacuum line, isnt it controlled solely by the haldex controller? Maybe vacuum holds it in low until the controller manually overrides?


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## [email protected] (May 14, 2009)

becker780 said:


> I dont understand why it would need a vacuum line, isnt it controlled solely by the haldex controller? Maybe vacuum holds it in low until the controller manually overrides?


 My theory is that the vacuum is for dis-engagement of the drive.


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## becker780 (Apr 30, 2013)

[email protected] said:


> My theory is that the vacuum is for dis-engagement of the drive.


 Hmmm I might explore this. If its just a leaking vacuum line I'll be kicking myself. Maybe Ill just run a new line under the car and see if it changes anything


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## Neal98 (Apr 3, 2013)

*Follow this link:*

There is NO vacuum going to the Haldex, or the controler.|This link is the study guide for the unit that an audi tec. would be taught from... http://www.vaglinks.com/Docs/Audi/TT/Audi_TT_Haldex_SelfStudyGuide.pdf


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## becker780 (Apr 30, 2013)

Neal98 said:


> There is NO vacuum going to the Haldex, or the controler.|This link is the study guide for the unit that an audi tec. would be taught from... http://www.vaglinks.com/Docs/Audi/TT/Audi_TT_Haldex_SelfStudyGuide.pdf


Wow that clears up so much. I didnt remember ever seeing a vacuum line under there but havent had time to get it on the lift in a while. Thanks for the great link


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## [email protected] (May 14, 2009)

Neal98 said:


> There is NO vacuum going to the Haldex, or the controler.


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## Neal98 (Apr 3, 2013)

*Yes, We have no vacuum back there*

What your looking at is the Haldex vent tube. it connects to nothing. should go into the frame.
As the fluid in the rear end/Haldex unit heats up, it expands....the air inside heats up and expands as well. if there were no vent, the pressure build up would cause seals to prematurely fail, causing fluid leaks.

From All Data Manual:


•Pull left and right vent pipes out of body member (arrow).


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## [email protected] (May 14, 2009)

Neal98 said:


> What your looking at is the Haldex vent tube. it connects to nothing. should go into the frame.
> As the fluid in the rear end/Haldex unit heats up, it expands....the air inside heats up and expands as well. if there were no vent, the pressure build up would cause seals to prematurely fail, causing fluid leaks.
> 
> From All Data Manual:
> ...


Good to know where it goes. Nothing in the Bentley makes any reference to it. Its strange that it does not just use a filter style vent found on air actuators.


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## ssweetd (Jan 17, 2006)

*Any updates?*

Any updates on the binding issues?


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## Neal98 (Apr 3, 2013)

*Still stuck in 4X4*

Have been working with the guys from Vag-Tech, and although they have been extremely nice and helpful, this problem defys logic. Last guess was to replace the ECU, as the Haldex is only commanded into high after engine is started. So, replace ECU with another, and still the same thing. only thing left at this point is another ABS module, I'm ordering tommorow. But to be honest I don't have much hope, as even with the ABS module unplugged, Haldex is still commanded into high! :banghead: It seems there have only been a couple cases of this reported, and from what I am reading, none were ever fixed, cars were just sold!


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## spydox (Apr 4, 2013)

Neal98 said:


> I know this thread is older then dirt, but, I am having the same problem. My Audi mk1 TT is stuck in 4wd, and will not release. turning right or left, you can here the tires grabbing and hear and feel the popping from the back, unplug the haldex controler, and car behaves normal. have replaced 2 haldex controls and the complete rear end, all to no avail. It seems the computer is requesting the haldex to lock up, but I have no idea why. Anybody else run into this?


wow nice trim !


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