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Haldex system confusion

Discussion in 'A3/S3 Forum (8L Chassis)' started by S3LOUD, Feb 9, 2012.

  1. S3LOUD
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    S3LOUD Member

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    yeaah it was me that said that. My garage quoted £150 for the job :).
    #41
  2. S3LOUD
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    S3LOUD Member

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    Yeah you said that before but i still am not too sure of how to test the haldex on the vagcom. Im guessing it will be under transmission. I checked there and it came up with no faults but i wasnt listening out for any sounds or anything. Ikll give that a go in the week and report back ;)
    #42
  3. Erf
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    Erf Member

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    do you mind me asking which garage? I'm in kingston so if its not too far from me, might give them a call. I've had quotes of over £300...!
    #43
  4. S3LOUD
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    S3LOUD Member

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    Whoaaa thats a lot :O! lol yeah of course its a place called yaashik motors that i used in wembley (near ace cafe) so not too far away from you. Give em a ring ;), they should have it done within the day for you aswell :)
    #44
  5. thegoal007
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    thegoal007 Another S3 owner....

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    You will not find any faults - most people don't with this kind of problem. Don't expect to hear noises until you run through the specific tests in vagcom - which by the sound of things you don't know how to run them.
    I need to step you through the instructions when I do it tomorrow when I take the car out for a spin. I'm pretty sure I've explained the how to run the test in the past on these forums.
    #45
  6. thegoal007
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    thegoal007 Another S3 owner....

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    I was right, I've alerady posted the instructions here..and above.
    Here it is again.
    ..... pick 22-AWD and then select output tests - 3 and hit start/next. This will go through putting the precharge pump on and off and the awd clutch off/on. When the precharge pump is on it should make a noise (I think). Obviously with the ignition on only.

    Once you have done this. try starting the car up and doing the test cycle again and then remove cable and see if you still have the problem.
    #46
  7. S3LOUD
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    S3LOUD Member

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    sorry i didnt recall reading that before. i'll try it using the steps youve explained and let you know what i find :). Thanks for all the help mate,
    #47
  8. S3LOUD
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    S3LOUD Member

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    Okay so the update! I plugged the car into vagcom, ran the haldex test and nothing came up as an issue however i did not hear any of the pumps or anything making any sounds during the test. I took the car for a drive and the issue had in fact gone away, but since turning the car off after that and driving it again the issue has come back.
    I am getting a very loud clicking/knocking noise from the back of the car when on turning or even when i slow down for a speed bump or something, as i change gear and re-engage i can hear that sound also. I am wondering if anyone may know what this could be and if this is some what interconnected with this haldex issue.
    Thanks for any help :)!
    #48
  9. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    This is interesting, mines making a grinding noise on full lock, as a result I'm changing the haldex fluid this weekend in the hope of solving it. If that doesn't solve it then I'll be watching this thread very closely!
    #49
  10. shariain
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    shariain Active Member

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    I had a similar problem with an old a3 quattro and it turned out to be a plug in the pillenium chamber (sp) might be way off the mark but might be worth a try. Basically it had a intermittent connection when driving.
    #50
  11. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    #51
  12. thegoal007
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    thegoal007 Another S3 owner....

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    that's strange because you can clear the problem by running through the tests when the car is running and as soon as you switch the car off and on again the problem re-appears - Which is same as me, BUT the knocking noise are not very loud at all and no noises until I leave the car in that turned postion for more than about 15 seconds....and normally I'm not as the car would be straightened out by that time.

    I've been cycling through those tests every time I take the car out and on a few occasions lately I found there was no need becuase the problem was not there- maybe it's getting it's knickers untangled ?

    Personally, from what you describe about your knocking noises, i think it's a completely different issue.
    #52
  13. Greig300
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    Greig300 Member

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    The oil in the haldex lubricates the clutch if not serviced the plates dry and grind and wear. the haldex spins the rear wheels at different speeds...one of the wheels rotates a shorter distance from the opposite hence why you can hear the noise at lower speeds or turning. It is far cheaper and easier to replace the rear haldex with a 2nd hand one.
    #53
  14. Erf
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    Erf Member

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    Can you replace just the haldex or do you need to replace the whole rear diff as one unit?
    #54
  15. thegoal007
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    thegoal007 Another S3 owner....

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    as I have previously mentioned it's probably cheaper in the long run to do the whole thing. There's just too many variables and costly ones.

    One person changed all the plates as mentioned by greig3000 and still had the problem and the other end of the scale some people have just changed the oil & filter and were OK.
    #55
  16. murran
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    murran Active Member

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    this wheel skipping problem is down to either, the haldex locking up 100% when it shouldnt be. or a purly mechanical fault with the rear diff locking up for some reason.
    what you guys are describing seems exactly the same as when you have an intentionally welded diff on a drifting car.
    i drove my e21 bmw drift car for around 3 years on the road so i know exactly what your describing.

    theory to understand how it all works..................
    obviously when you drive with a welded diff when going straight forward both wheels turn at the same speed, but when you turn a corner the inside wheel turns less and the outside wheel turns more. if the diff is locked then one of the wheels has to skip, the inside one! when turning a corner this effect is like a constant resistance to rolling (braking).
    if the car is 4wd then when turning a corner all the wheels are turning at different speeds..... but the sum turns of both front wheels will be different to the sum turns of both rear wheels.
    now on say a landrover.... with a front, center and rear diff. you lock the center diff and turn a circle on full lock at like tickover in first gear, you get this wheel skipping feeling somewhere and understeering feeling you dont get with the diff lock off.
    do the same in my bmw it was blatently obvious the inside wheel is skipping alot!

    on a tt s3 you dont actually have a center diff! the gearbox is driving the prop all the time the haldex takes the place off a center diff and should allow the the difference in the front wheel turns and rear wheel turns at low speeds completely without this resistance to rolling wheel skip.

    why dont you guys just do some basic things/checks to rule stuff out rather than guessing stuff and messing about with vag-com?

    on these cars if you simply unplug the haldex controller the car should be completely fwd. if your wheel skipping fault is still there, then were getting somewhere...... were 90% sure the haldex is ok.
    jack the back of the car up turn one back wheel, does the prop turn?
    with the haldex unplugged it certainly shouldnt be turning the prop, if it does then the clutch pack is locked when it shouldnt be.

    if the prop is behaving fine ie not turning. when you turn the wheel is the other wheel turning in the same direction? opposite direction? not turning at all? can you hold one still and turn the other?
    with the haldex unplugged you should be able to turn either wheel independant of each other without the prop turning.
    does it feel notchy or clunky while turning one one way and the other wheel the opposite way?

    if the this is all correct and the fault is only there with the haldex plugged in then you can say its deffinatly that.
    Last edited: May 4, 2012
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  17. Greig300
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    Greig300 Member

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    Removing the haldex fuse will still cause the noise as its mechanical fault. Just replace the haldex unit. The main box.
    #57
  18. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    FYI it looks like my problem is the earth strap:

    [​IMG]

    Oh, and pulling fuse 31 did solve the dragging issue in my case...
    #58
  19. cecilthesausage
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    cecilthesausage ...It's Never Finished...

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    I've been having this problem since I upgraded my Haldex to a blue controller...when I do a 3 point turn my back wheels feel as if they are locking up and they make a clunking noise....Plus my Haldex pump is constantly ticking....
    #59
  20. Greig300
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    Greig300 Member

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    The ticking is from the pre charge pump. Usually on ignition it will constantly suck and tick. Your wiring on the connectors to the haldex will be corroded or dirty. Giving the connectors a clean with electrical fluid and removing the junk it gathers can solve that problem.
    #60
  21. S3LOUD
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    S3LOUD Member

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    ohhh really?? To be honest nothing surprises me with S3's loool. I'll defo have a look a that and see if i can find any issues there :), Thanks a lot mate!
    #61
  22. S3LOUD
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    S3LOUD Member

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    hmmm okay thats all defo a lot of different stuff to try. Firstly i am going to try taking out fuse 31 this morning and see if this resolves anything. If not then it is defo time to try the list of hints and tips above. So far i have done 2 oil and filter services, replaced the haldex clutch pack and haldex controller and the issue still persists. I realised after this that the diff should also be replaced so i have the diff which matches the clutch and controller ready to also go in at the start of next month.
    I will let you all know if pulling the fuse resulted in this dragging feeling no longer occurring. If that is the case then what would this mean???
    #62
  23. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    If pulling the fuse solves it then it means the issue is electrical so check your wiring...
    #63
  24. Sam_
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    Sam_ Down under

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    Mine has always groaned on full lock from the rear but I read that it was normal? It's definitely not locked in 4wd as I pulled the fuse when my haldex leaked (changed controller and gasket was on wrong) and it was FWD for sure. Also very rarely when I launch, I catch out the Haldex and the front wheels spin very briefly. Anything else it could be? I am getting the rear diff and haldex serviced shortly along with all the other fluids.
    #64
  25. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Is the full lock groaning different with and without the fuse?
    #65
  26. Sam_
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    Sam_ Down under

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    Not tried without the fuse but will tomorrow. If it does what does that mean?

    I have a blue controller and it all looked pretty mint under there so not sure if the earth strap is rusty or not.
    #66
  27. k1ano
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    k1ano Member

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    Fundamentally, rear (or front) wheel skipping should only occur if a diff is locked and preventing differential wheel speeds on the same axle ... Plate diffs have inherrent drag and of course welded diffs will always drag, torsen diffs will lock or transfer torque but only when one wheel tries to spin.

    The rear diff on the haldex system (on the S3 8L) is open so the haldex clutches working or not should have no impact on whether one rear wheel is grabbing or not whilst cornering unless the open diff is faulty due to perhaps one of the planet gears breaking and locking it up - this could make grinding noises if the broken parts are rattling about but still in place. Some systems use electronic braking of individual wheels to alter the torque distribution on the axle, to compensate for the diff being open, but I think the S3 only has this on the front wheels and not the rear so this should not cause rear wheel locking either.

    Martin
    #67
  28. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Almost correct. On mine the earth strap failed and caused the haldex clutch to permanently engage the rear drive. Removing fuse 31 disengaged the haldex clutch and released the clutch. Yesterday I had the earth strap replaced and subsequently replaced fuse 31, this has resolved the dragging.

    Sam_ - TBH I'd be surprised if it is actually mechanical failure, unless you've done interstellar mileage or something out of the ordinary has happened. For reference here's an explanation of the haldex system that I found useful: http://www.billswebspace.com/HALDEX.pdf
    #68
  29. S3LOUD
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    S3LOUD Member

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    Okay so a little update with mine, (sorry been a bit busy with work). This morning on before i left for work i removed the haldex fuse and now obviously as a result it is running front wheel drive HOWEVER the dragging issue has completey disappeared!
    Does anyone know what this may mean???
    Thanks a lot for all the help its much appreciateddd! :)!
    #69
  30. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    It means your fault is electrical. Checked the earth strap yet?
    #70
  31. S3LOUD
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    S3LOUD Member

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    Hopefully a ramps free sometime during the day today and i'll quickly throw the car on and take a look and hope that we've sourced the issue. Do you know where abouts the earth strap is by any chance just so i know where exactly im looking??
    Cheers mate!!
    #71
  32. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    You don't necessarily need a ramp TBH but its easier if you have one. Under the car, on the passenger side at the rear end. The strap runs from the diff to the body under the boot area: It might look like this:

    [​IMG]

    On the left of the pic you can see the diff end of the rear passenger side drive shaft, should help you get your bearings.
    #72
  33. S3LOUD
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    S3LOUD Member

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    wow thanks for that! :D im hoping that thats all that is causing me the issue. I will try and check that today and keep you updated.
    Thanks mate thats made my life a lot easier when looking for it!! Top man!
    #73
  34. cecilthesausage
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    cecilthesausage ...It's Never Finished...

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    Is this my Earth Strap...[​IMG]
    #74
  35. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    No, that looks like arm for the xenon level sensor, which looks like its been disconnected.
    #75
  36. thegoal007
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    thegoal007 Another S3 owner....

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    there you go so many people with the same problem and so many reasons. Pulling the fuse on mine doesn't resolve the issue, but running through the output tests (just like you) of vagcom clears the problem. so go figure !

    What I would say is leave the fuse out for a week just to make sure it really does cure the problem because I have to remind you that it is not a problem that is consistent.
    #76
  37. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    No... thats a broken headlight level sensor... you nee to fix that for the MOT...

    <tuffty/>
    #77
  38. cecilthesausage
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    cecilthesausage ...It's Never Finished...

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    Its at the rear of my car Paul.... Passenger side
    #78
  39. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    Correct, but it is for the headlights. Look above this attached to the boot floor for the earth strap.
    #79
  40. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    #80

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