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Techincal question for any Haldex controller "experts"

Discussion in 'A3/S3 Forum (8L Chassis)' started by Scullies, Aug 5, 2012.

  1. Scullies
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    Scullies Well-Known Member

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    [Aug 5, 2012]
    I have opened up a haldex controller unit, to see how it all works. Simple mechanics controlled by a circuit which gets info from ecu.

    Below is 3 pictures of the pin that restricts the flow of the haldex oil.
    picture below with the oil flow fully open - No haldex operation.
    pos 1 open.JPG

    Next is pin half way. Now for the 1st question.
    With the pin in this position, is the haldex on approximately 70/30 power split?
    pos 2 half.JPG

    Lastly, the pin is fully closed.
    This would stop all oil flow and increase pressure on haldex. In this position is the haldex on a 50/50 power split?
    pos 3 closed.JPG

    Working on some top secret stuff here :yum:[​IMG]
    Last edited: Aug 5, 2012
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  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Aug 5, 2012]
    I e never seen anyone open up a haldex controller before so you might struggle for an answer from us lot.

    It's good to see new things.
    #2
  4. jezzy
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    jezzy Member

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    [Aug 5, 2012]
    interesting stuff, is that the controller or the haldex diff?
    #3
  5. Scullies
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    Scullies Well-Known Member

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    [Aug 5, 2012]
    Heres another picture of the inside. I have removed the wiring harness though.
    haldex info 1.jpg

    That pin is part of the haldex controller.
    #4
  6. jezzy
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    jezzy Member

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    [Aug 5, 2012]
    ive read of people try to hack the haldex controller to no avail.
    So if you manage it, you could become a very rich man.
    and i could be your uk outlet my new best friend buddy pal mate -)
    #5
  7. Scullies
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    Scullies Well-Known Member

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    [Aug 5, 2012]
    That is the idea, waiting for some components to be delivered then get programming.
    In theory it should work, time will tell :)
    #6
  8. antwan
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    antwan Member

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    [Aug 5, 2012]
    I thought the haldex works like a hydraulic wet clutch/ brake setup, found on many bikes and plant, and the ayc system on evo's, so

    min oil pressure to the clutch plates would be disengaged (no lockup)
    max oil pressure to the clutch plates would be locked (50/50 power split)

    so when the pin is fully closed, there would be no oil pressure (disengaged) and fully open would be max oil pressure ( locked), also does the solenoid that controls the pin, works on pulses ( duty cycle) rather than as a normal valve restricting oil flow ?

    Am I on the right path with my thoughts, or looking at it the wrong way ????
    #7
  9. jamie408
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    jamie408 New Member

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    [Aug 5, 2012]
    id of said the pin is open and you get 50/50 too.
    #8
  10. superkarl
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    superkarl MAN OF STEEL

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    [Aug 5, 2012]
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  11. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    Thanks Karl,
    I have already looked at the haldex pdf. It doesn't say if "max pressure" is 50/50 split or OEM split.

    What I'm not sure about is, if the OEM haldex controller pushes the pin to the fully closed position or not.
    My thinking is that the OEM haldex controller never uses the "max pressure" setting, maybe it only closes a little to apply the max OEM power split.


    - Darren
    #10
  12. jojo
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    jojo S3 Drift King! Staff Member Moderator

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    [Aug 6, 2012]
    On page 31

    This suggests to me that the OP is correct with his assumptions on how it works in the first post!
    #11
  13. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    haldex oil flow.jpg

    Some more info to help others understand

    No assumptions here :p
    #12
  14. JoeD
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    JoeD Member

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    [Aug 6, 2012]
    Interesting, credit to you, seem to know your stuff. What is it you are trying to ahceive? Constant 50/50 split or just an even distrubution when the haldex is activated?One question though, is it a realstic option? Would this stress any other componants or would you run the risk of any damage running 50/50 split constant?
    Last edited: Aug 6, 2012
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  15. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    My plan is to program a small circuit board to control the ORIGINAL haldex controller from a dash mount switch, I should be able to set the power split to any ratio, be it fully adjustale from 100/0 through to 50/50. Or have specific setups like, fwd (100/0), race (65/35) or drag (50/50). The exact split will be difficult to measure as the pin only moves a tiny bit when adjusted.
    The OEM haldex has an oil temp sensor that cuts out the haldex operation when the oil reaches 100 degrees to protect the clutch plates, but continued driving with the haldex in any activated position is going reduce clutch plate and oil life.
    Once I get the actual control part working, I will need to look into using the temp sensor to cut the haldex operation or at least alert the driver the haldex oil temp is high.
    #14
  16. superkarl
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    superkarl MAN OF STEEL

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    [Aug 6, 2012]
    because the car doesnt have a centre diff, its not a great idea having constant 50/50 split i dont think, there still needs to be some change in drive from front to rear.

    i think scullies right tho with his annotated pics above
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  17. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Aug 6, 2012]
    I like the idea behind all this but I don't really see the point in interfering with the Haldex as it already does a good enough job! Dump the clutch at 5k on the drag strip and it just goes.
    #16
  18. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    Also, I heard that 50/50 is like diff lock on a 4X4. You can't do tight turns with it engaged as it will stress the gearbox and cause damage.
    #17
  19. superkarl
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    superkarl MAN OF STEEL

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    [Aug 6, 2012]
    good shout, yeh it will need SOME slip

    to add, incase people dont know, front wheels spin faster than the rear in a car without a centre diff.
    perhaps this is the reason for the common dragging issue, and the haldex isnt allowing any slip for the turn
    Last edited: Aug 6, 2012
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  20. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    Well, firstly it would be an upgrade for those who want to and SECONDLY, (the reason I need it) would be a cheap option to get a non responsive/damaged haldex controller working again but in a manual way.
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  21. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Aug 6, 2012]
    I like the 2nd one ;)
    #20
  22. Rosso TT
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    Rosso TT Member

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    [Aug 6, 2012]
    I did dismantle one of those 5 months ago to look at the inner working of it.
    If you know your way around electronic circuitry you can controll the stepper motor that drives the needle remotely, unfortunately i'm not very good at electronic stuff.
    Theres a company that makes a manual haldex controller called SQS, but you need to get under the car to adjust it.
    Then there's the hadex competition that keeps the power split to 50/50 all the time but some people reported some rear wheels hopping at low speed.
    And yes needle fully in gives you 50/50 power split.
    #21
  23. Alex C
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    Alex C Well-Known Member

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    [Aug 6, 2012]
    how about enabling 4x4 when braking? that way you have you engine braking traction applied to all 4 wheels instead of just the front?
    #22
  24. Scullies
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    Scullies Well-Known Member

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    [Aug 6, 2012]
    Yeh, seen the SQS controller. That's what has put a bee in my bonnet about sorting a controller from the dash.
    Rear wheel hopping is very bad. When you turn in normal fwd only, your outside rear wheel moves faster than your inside rear wheel. So when you on 50/50 split, (to my knowledge the rear diff is locked, meaning both wheels turn at the same speed. At least this is what diff lock does on an off-road 4X4 vehicle) the rear diff is trying to turn both wheels at the same speed, but one wheel turns faster than the other causing the other wheel to skip. Now imagine how much torque is being applied to that wheel to allow it to skip over the solid tarmac. Something is going to bend/break. Driving like this is snow, sand or mud is ok as the wheels will be slipping while they try grip the surface.

    If I can get this to work the haldex will not disengage unless you select FWD or it trips with overheat alarm (design dependent)
    So you will have haldex braking and haldex when in a corner and not on the throttle.
    #23
  25. Colly
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    Colly The Tangerine Machine

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    [Aug 6, 2012]
    im really intrigued as to if this works as id love to do summit with mine
    #24
  26. rhys1210
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    rhys1210 Member

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    [Aug 6, 2012]
    Doesnt the haldex have a open diff in it like the front to enable both rear wheels to rotate at different speeds. I can see the problem of the wheel speed front to back but not side to side. Or have i got it wrong?

    Hope it works for you as i would be interested in something like this.
    #25
  27. Alex C
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    Alex C Well-Known Member

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    [Aug 6, 2012]
    both the front and rear are open diffs AFAIK
    #26
  28. rhys1210
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    rhys1210 Member

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    [Aug 6, 2012]
    So having 2 open diffs should mean all wheels can turn at different speeds?

    come to think of it you dont get well hop when cornering on the standard controller, so having full time 4 wheel drive shouldnt cause a problem.
    #27
  29. Colly
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    Colly The Tangerine Machine

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    [Aug 7, 2012]
    Has anyone got any experience of the sqs controller?
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  30. rhys1210
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    rhys1210 Member

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    [Aug 7, 2012]
    I dont think you can use this on the S3 with out warning lights coming on. As it is designed for people putting haldexes in mk1 and 2 golfs really which wont have all the sensors we have.

    Taken from sqs website

    SQS Racing | Haldex Regulator

    Hydraulic controler for Haldex transmission unit used in VAG Mk4 cars.
    Simple and reliable solution for Racing and special build cars where is not used original CAN-Bus wiring.
    #29
  31. S3Zek
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    S3Zek Member

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    [Aug 7, 2012]
    I know someone who has made his own, its just a adjustable valve and some pipe work to the inside of the car from the heldex adjusting the pressure adjust the split.I think It's as easy as that and the kits only about 40ish quid I think (don't quote me on that), but like said if it was on the s3 then the dash would prob light up like a crimbo tree. Run something like Mbe like he dose and it wouldn't be a prob
    this is it in action 2010 NEW!! A K Bodycraft 1/4 mile 9.89 seconds @ 148.7 MPH VW Mk1 Golf Turbo GTi Spring Festival - YouTube
    #30
  32. S3Zek
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    S3Zek Member

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    [Aug 7, 2012]
    By the way I didn't read the last post lol
    #31
  33. Scullies
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    Scullies Well-Known Member

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    [Aug 13, 2012]
    A little update, I have managed to get the circuit up and running. Here is a quick video of the motor that is inside the haldex controller. I am able to control the direction by turning the knob "not in the video". The coding still needs some fine tuning and need to iron out some issues.
    Also I have noticed the oil temp sensor is located in the return side of haldex controller. This means its not a good idea to run a 50/50 power split as the oil temp sensor will not see any oil and wont be able to read the oil temp. So I'm thinking a 55/45 power split is a better safer option.
    Video - [video]http://s1253.photobucket.com/albums/hh584/Scullies/?action=view&current=2012-08-13002.mp4[/video]
    Last edited: Aug 13, 2012
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  34. rhys1210
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    rhys1210 Member

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    [Aug 13, 2012]
    your video is in a private album.
    #33
  35. Scullies
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    Scullies Well-Known Member

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    [Aug 13, 2012]
    Thanks bud,should be sorted now.
    Last edited: Aug 13, 2012
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  36. Barks
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    Barks Member

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    [Aug 13, 2012]
    Good interesting project, just a thought......a relay to switch the stepper between Haldex and manual override at the mating connector would be good for those with a working haldex.
    #35
  37. Scullies
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    Scullies Well-Known Member

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    [Aug 18, 2012]
    My set up is going to use the motor inside the haldex unit and bypass the haldex circuit, so won't be able to have std and manual options.

    Little update, I have got the motor moving the pin inside the haldex housing now. Have smoothed out the movement but still needs some fine tuning.

    Picture of the haldex unit that mates up to the diff

    DSC03290.jpg

    and some very boring videos of the pin moving as I turn the control knob. Feel free to waste a minute or two of your life. :p

    [video]http://s1253.photobucket.com/albums/hh584/Scullies/?action=view&current=clipnomusic2.mp4[/video] - with background music

    [video]http://s1253.photobucket.com/albums/hh584/Scullies/?action=view&current=clipnomusic1.mp4[/video] - no music
    #36
  38. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Aug 18, 2012]
    exsqueaze me?
    #37
  39. TTazRS
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    TTazRS New Member

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    [Oct 10, 2013]
    Any update on this?
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