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How to: S3 exhaust flap mod

Discussion in 'A3/S3/Sportback (8P Chassis)' started by Staz, Jan 5, 2009.

  1. Staz
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    Staz is a retronaut Staff Member Moderator VCDS Map User

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    [Jan 5, 2009]
    Recy G sent me the link to the old thread about this mod:

    http://www.audi-sport.net/vb/showthread.php?t=42546

    I knew nothing about it as I was away at the time but I thought I'd give it a go, so here it is.

    You will need:

    1x flat head screwdriver
    1x pliers
    about 50cm of thin locking-wire

    So here is the lever which moves the flap:

    [​IMG]

    And here is the flap inside the left pipe:

    [​IMG]

    Firstly you will need to use the screwdriver to pop the lever out of the hole in the actuator arm so it looks like this:

    [​IMG]

    As was pointed out by siu00adg (post #73) if you leave it like that the flap could quite easily close itself. More than likely the flap would turn around completely and end up about 170 degrees from the closed position (i.e. the flap nearly closed but facing the opposite way) and stay there.

    Not only this but the lever arm sits just where you would like the actuator arm to sit and would still be moving as normal so would push the actuator arm out of position.

    I decided I would use some .457mm locking wire to tackle the issue (I only had 2 sizes in the locker and the other was too thick):

    [​IMG]

    I tried a couple of ways of routing the wire to hold the actuator arm in place but this is how it ended up:

    [​IMG]

    I started by wrapping the wire through the hole in the arm a couple of times. I then put in a few twists to keep the wire secure. Then I looped both ends around the mount from the front to the back and then tied them off together against the first section of wire.

    You may find a better way to do this but the idea is there.

    The flap position is not perfectly flat but I would have thought it's free flowing enough anyway:

    [​IMG]

    I have not had a proper drive to try it out yet, only drove back from the workshop to my room, 1/2 mile at 20mph limit. I will be going out later to get some food so I will post results then.
    #1
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  3. VRStu
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    VRStu Just Looking VCDS Map User

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    [Jan 5, 2009]
    Interested to know how you get on with this.
    #2
  4. Khufu
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    Khufu Active Member

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    [Jan 5, 2009]
    what's the issue with the flap? What does it do? Is it like the EXup valve on Yamaha motorbikes?
    #3
  5. Staz
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    Staz is a retronaut Staff Member Moderator VCDS Map User

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    [Jan 5, 2009]
    Well I'm back now, and I can't say I noticed any difference!

    Maybe a bit more popping on the overrun but that's it.
    #4
  6. FazS3
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    FazS3 Member

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    [Jan 5, 2009]
    Go out for a real blast then report back fella :p
    #5
  7. Recy G
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    Recy G New Member

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    [Jan 6, 2009]
    Have got the NSN for that lock wire please Staz. Haha
    #6
  8. VRStu
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    VRStu Just Looking VCDS Map User

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    [Jan 6, 2009]
    ............ and the wire locking tool !!! :readit:
    #7
  9. Staz
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    Staz is a retronaut Staff Member Moderator VCDS Map User

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    [Jan 6, 2009]
    Lol you can have as much as you want when you come down mate!

    It's so thin you don't need the tool. Or maybe that's because of my massive finger strength :ninja:
    #8
  10. JohnS3
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    JohnS3 Active Member

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    [Jan 6, 2009]
    and that' s another story.... :undwech:
    #9
  11. hatmeow
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    hatmeow Turbo is the only way....

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    [Jan 7, 2009]
    I guess this flap does will not exist if the exhaust was replaced with an aftermarket exhaust? What does this flap do anyways? Put up the back pressure during low RPM?
    #10
  12. Staz
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    Staz is a retronaut Staff Member Moderator VCDS Map User

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    [Jan 7, 2009]
    It certainly is! :arco:

    It won't be on an aftermarket no. I don't know what it does tbh. I don't know when it opens and closes but why would you want back pressure anyway? I thought back pressure was a bad thing as it retards power!
    #11
  13. JohnS3
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    JohnS3 Active Member

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    [Jan 7, 2009]
    I thought it was to make the exhaust quiet at low revs and make more noise at high revs. Could be wrong though....
    #12
  14. Carl.S
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    Carl.S Member

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    [Jan 7, 2009]

    correct, the ideal situation on a turbo car is no back pressure at all hence 3" systems :)
    #13
  15. magnus911
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    magnus911 R8GGA

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    [Jan 7, 2009]
    It's a drive-by noise EU regulation thing. Up to 3500 rpm; it keeps one side shut so the exhaust makes less noise; over 3500rpm the flap opens and the exhaust is slightly louder.

    Even my MGTF had one which I also overrode. (Oh dear yes I did just admit to having one of those at one point)
    #14
  16. Staz
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    Staz is a retronaut Staff Member Moderator VCDS Map User

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    [Jan 7, 2009]
    I see! I was listening out for extra noise at higher revs. Can't say I noticed a difference lower down either.
    #15

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