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Launch question

wuta3 Apr 27, 2020

  1. wuta3

    wuta3 Well-Known Member

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    Hi all,

    So I have done a few launches in my 2018 RS3 ...

    I have noticed that after planting the brake pedal and engaging the throttle ... the clutch bites a bit and the car lurches, then the revs drop, the clutch disengages and then it revs freely to 4k rpm or whatever it is ready for launching when the brake pedal is released.

    Now, I accidentally did this without traction control off, and after experimenting it appears to exhibit the same behaviour regardless of traction control. The car launched fine with traction control on (not in sport, just on), but with an initial slight lurch before the gearbox sorts itself out.

    So, is this initial clutch bite normal (it happens with TC on, in sport, or off) and is the initial bite (before the TCU realises it aint going anywhere) likely to wear the clutch?

    Is TC off just a recommendation? or is that central to the launch operation? Because it seems like you can launch anyway ...
     
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  3. Bonstio

    Bonstio Active Member

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    Winch does not work with TC on. It must be half off or fully off. In my 2018 model. I feel no clutch bite when it is holding the revs. Or maybe I misunderstood you somehow?

    Sent from my SM-N975F using Tapatalk
     
  4. Bonstio

    Bonstio Active Member

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    Launch not winch. Gah.

    Sent from my SM-N975F using Tapatalk
     
  5. jebusRS

    jebusRS Member

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    pretty sure traction control has to be fully off (long press, warning on dash) for the launch to work properly. It tells you all this in the owner manual.
     
  6. wuta3

    wuta3 Well-Known Member

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    This was my understanding. However, the car behaves exactly the same regardless. Normally i'd full-off (long press)

    The main question is if the following is normal:
    1. Select S on gearbox, Long-press off TC
    2. Plant foot on brake
    3. Apply a small amount of accelerator ... car bites momentarily, then revs drop
    4. Apply accelerator again ... no bite, car revs up to launch limit
    5. Take foot off brake and launch
    That initial bite of the clutch doesn't feel right to me. Does launch depend on being quite rough with the go pedal?
     
  7. Bonstio

    Bonstio Active Member

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    I'd have to test. But I always completely floor both pedals.

    Sent from my SM-N975F using Tapatalk
     
  8. wuta3

    wuta3 Well-Known Member

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    Yeah the first time I did it I was a bit hesitant with the accelerator to ensure it wasn't biting as I didn't want to fry the clutches ... and found it did bite.
     
  9. Bonstio

    Bonstio Active Member

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    Made that mistake on several occasions. Gotta be dynamic, sport and I turn off auto handbrake. Otherwise it does bite and I wince.

    Sent from my SM-N975F using Tapatalk
     
  10. wuta3

    wuta3 Well-Known Member

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    That's my setup too when I launch, but it still bites. If that's normal if being a bit too gentle with the throttle then fine, but when in dynamic/sport/TC-off etc building the revs does bite then it decides not too. I can film it if needed.

    Just don't wanna kill my clutches if it isn't launching right.
     
  11. Bonstio

    Bonstio Active Member

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    I think you'll know. When done right, the revs stick and the turbo pressure builds. Upon launch, the gear changes are noticeably different too, no time to make the pops on upshift.

    Sent from my SM-N975F using Tapatalk
     
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  13. wuta3

    wuta3 Well-Known Member

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    Yep the actual launch is fine, and exactly as i'd expect, it is just the initial bite before the clutches disengage and I can bring it up to the launch rev limit cleanly that seems odd.

    Because of that initial bite I end up "tickling" the throttle to get the car to disengage the clutches (all the time while my foot is on the brake) ... then slam it. The initial bite makes me think straight up slaming it will burn clutch
     
  14. Bonstio

    Bonstio Active Member

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    Maybe take a vid. And stamp on both pedals for good measure.

    Sent from my SM-N975F using Tapatalk
     
  15. wuta3

    wuta3 Well-Known Member

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    Yeah just a bit worried about stamping because if the clutch is engaged while my foot is planted on the brake (which it is) it may cause damage.

    I'll go and take a video
     
  16. D0C

    D0C Well-Known Member

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    It only has to be half off, one press.
     
  17. wuta3

    wuta3 Well-Known Member

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    OK here is the video. At the point I touch the accelerator, the brake is pressed hard.



    I can feel the car bog down, fighting the brakes, which indicates the clutch is engaged. It isn't freely revving and throttle causes the car to try and turn the wheels, even with my foot hard on the brake.

    I don't want to rev it any harder, because I can feel it trying to turn the wheels. My understanding was the clutch is disengaged until you lift your brake foot.

    This is the same regardless of TC state
     
  18. Bonstio

    Bonstio Active Member

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    Oooo. That's not right. It's meant to sound exactly like this:

    I can't see a light so it looks like your handbrake is off? Do you have the auto option?

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  19. wuta3

    wuta3 Well-Known Member

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    It has hill assist and the handbrake applies itself in park
     
  20. wuta3

    wuta3 Well-Known Member

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    Don't get me wrong, I can make it do that, if I mash the throttle, but my mechanical sympathy says that i'm just shagging the clutch because it is clearly engaged.

    When the revs first dip, that's the car doing it, my throttle foot is level. Is it detecting the launch and just "biting" the car. The harder I press the accelerator, the car bogs down at a constant rate.

    Actually I noted in that Instagram video the car does look like it bogs down a tiny bit when the revs rise ...My car bogs down much more and the ECU backs out of the revs
     
    Last edited: Apr 27, 2020
  21. Bonstio

    Bonstio Active Member

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    I have to turn mine off.

    If you already do this, I guess you might have a problem.

    Sent from my SM-N975F using Tapatalk
     
  22. wuta3

    wuta3 Well-Known Member

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    I'll double check what's going on here, but I don't really see any way to change hill assist, and the parking brake only applies in P
     
  23. Sequence

    Sequence Member

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    The launch control system is only active with partial or fully disabled traction/stability. what you are doing without tc off can best be described as brake boosting something i wouldn't recommend doing in a car like this. With launch on these the car will detect the scenario of traction off gearbox in s and brake depressed followed by flatting the accelerator at this point the clutch is not engaged but boost is built then when you let off the brake you will get the perceived few milliseconds of delay and then the car will bolt, this delay is the clutches slipping into first. One thing that maye be down to your issue with tc off, is the car up to temp oil 80 or so and driven for a good 15 min or so as the gearbox also has to warm up. steering wheel also dead straight ?
    With what you are doing the clutch is engaged and trying to transmit power this will eventually overheat them if held to long if you were to let off the brake you would then also semi launch.
     
  24. wuta3

    wuta3 Well-Known Member

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    TC is off, car is warm and steering wheels is straight. I'm in S+dynamic.

    It really boils down to not expecting the clutch to bite with the brake pedal down hard.
     
  25. deepy

    deepy Active Member

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    Had the same issue when I had my Golf R, turned out that the gearbox oil wasn't up to temp, a quick 10 minute spirited drive and all was good on the next launch.
     
  26. wuta3

    wuta3 Well-Known Member

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    Hmm, I'd been smashing about for 30 mins before the recorded attempt. I take it there should be no bite at all with the brake fully down?
     
  27. deepy

    deepy Active Member

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    There is definitely something amiss as you appear to be going through the launch procedure correctly.
    Just a thought, but have you had the car from new? If not then perhaps the previous owner done a lot of launching and the car has reached the limit for Launching, which is supposedly 200
     
  28. Bristle Hound

    Bristle Hound Moderator Staff Member Moderator

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    @wuta3 - Direct lift from the handbook :thumbs up:

    [​IMG]
     
  29. wuta3

    wuta3 Well-Known Member

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    That's what i'm doing and I can't imagine overheating at the time i've done it. Perhaps im just being too gentle with the throttle and confusing it.

    Can someone follow the proceedure and rather than floor the accelerator ... just press it 1/4 and see if the clutch is biting?
     
  30. wuta3

    wuta3 Well-Known Member

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    There's a limit?! wtf ... I have not had the car since new, but since year old, and given the lifetime mpg was 28mpg when I got it I can't imagine the old driver did 200 launches.
     
  31. D0C

    D0C Well-Known Member

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    If you have everything set up and only partially apply the accelerator then it will give the feeling that it’s loading up against the brakes. You have to be hard on the brake and mash the throttle.
     
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  32. wuta3

    wuta3 Well-Known Member

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    That's what I was after. It just felt so "wrong" because I could feel it loading against the brakes and my inner engineer was like "im gonna smell clutch if I mash the throttle" because I wanted to check the clutches were disengaged so "felt it out" with some gentle throttle.

    If that's expected that's fine :) just feels ******* weird
     
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  34. Bristle Hound

    Bristle Hound Moderator Staff Member Moderator

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    @deepy @wuta3 - See below thread ref LC limit :thumbs up:
    https://www.audi-sport.net/xf/threads/launch-control-limit-fact-or-fiction.245027/

    Quick answer -
    https://www.audi-sport.net/xf/threads/launch-control-limit-fact-or-fiction.245027/#post-2468903
     
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  35. wuta3

    wuta3 Well-Known Member

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    Bristle Hound likes this.
  36. D0C

    D0C Well-Known Member

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    Take a brave pill, get the car up to temp, traction control one press (half off), turn auto hold off etc, into dynamic. Then HARD on brake, mash the throttle hard to the floor, revs should hold at 3500-4000rpm then let go of brake.
     
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  37. wuta3

    wuta3 Well-Known Member

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    I've launched properly a few times and love it. I just wanted to check this initial bite issue before I go mad, as when I floor it roughly the revs to get to 4k and hold with a lovely burble just after an initial brake-loading and rev dip like it has to think "ah he doing a launch, best disengage the clutch"
     
  38. T-1000

    T-1000 Well-Known Member

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    If it’s a facelift you can look how many launches it’s done with VCDS.


    Sent from my iPhone using Tapatalk
     
    deepy likes this.
  39. deepy

    deepy Active Member

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    Last edited: Apr 28, 2020

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