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Thread: About tyre lifting

  1. #1
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    About tyre lifting

    I'm having some inner front tyre lifting during cornering. I just drove two sessions using the following anti-roll bar strengths:

    Session 1: Front swaybar 80 N/mm, rear swaybar 10 N/mm
    Session 2: Front swaybar 70 N/mm, rear swaybar 0 N/mm

    But the results of adjustment seem contradictory to me: session 2 has more inner front tyre lift. The inner rear tyre lifting, though, has reduced further from what little there was in session 1 (which is what I was expecting).

    Why would inner front tyre lift increase from softening both anti-roll bars? If the culprit is softening the rear anti-roll bar at the same time, what is the reason for this?

    I suppose I could also try fixing the original problem by adjusting damper settings, although from what I understand, this would only help for limited time and would not help after enough body roll has eventually built up. For example, I could try softening the slow rebound on the problematic wheel, if I'm correct in assuming that a stiffer setting 'pulls' the wheel off the ground during body roll. Or would a stiffer setting actually keep more weight in that corner for longer, slowing down the body roll and thus suspension extension? What about stiffening the slow bump setting on the other side of the car, to resist compression and body roll? Are fast damper settings worth looking into as well?

    Alternatively, would raising front ride height be a good option? I'm assuming doing that would increase the maximum extension distance of the spring... though wouldn't this then also increase body roll on that end, which in turn would at least partially undo the benefit of longer maximum extension distance?

    Whew. Any help on this is greatly appreciated.

  2. #2
    GTE Pilot blinkngone's Avatar
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    Hey, I think you are talking about droop limiting. Here is a link. https://www.f1technical.net/forum/viewtopic.php?t=21565

    The Aston Martin Vantage GTE does this a lot for me. It looks really cool in replays on slower corners, it is also a 2014 car. I don't have the issue on the newer GTEs which coincidently are typically faster for me anyway.
    Bikes wrecked-77 Suzuki RM125, 78 Honda Elsinore 250, 81 Honda CB900F, 2000 Kawsaki ZX12R(2), 2001 Honda F4I, 2005 Yamaha R1. A bike hasn't been made I couldn't wreck, spectacularly, but I'm retired now.

  3. #3
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    Thank you for the link, I've read it now.

    Actually I came up with a theory while I was walking - not sure if that's what's going on but here goes.

    So usually too stiff anti-roll bar causes wheel lifting because the bar wants to equalize both wheel's distance from the wheel arch, let's put it this way. In which case, the spring may not have, and won't be able to, extend fully. But in my case, it might have been that it actually wasn't so much the anti-roll bar forcing the wheel to lift, but the fact that the spring became fully extended as the body rolled, could not do so any further, and was left hanging in the air. And when I softened both anti-roll bars, more total body roll occurred (though some of the increase may have been distributed to the now-softer rear?), making the situation worse: the problematic corner of the car was now even higher from the ground, with the spring still limited in extension like before.

    If that makes sense... feel free to correct me where I'm wrong, always looking forward to learn more (and preferably facts, hehe).

  4. #4
    GTE Pilot blinkngone's Avatar
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    Hey I never figured it out with the AM GTE. I just set up the car like I normally would and ignored the wheel in the air. I was able to make things worse as you experienced. I have only remembered 1 other post on this subject(droop), lifting rear wheels in the air is common on the compact front wheel drive cars. What car/track are you experimenting with?

    Oh yeah I forgot, I think you can lift the inside wheel on the 1973 Porsche RSR.
    Last edited by blinkngone; 08-06-2019 at 00:27.
    Bikes wrecked-77 Suzuki RM125, 78 Honda Elsinore 250, 81 Honda CB900F, 2000 Kawsaki ZX12R(2), 2001 Honda F4I, 2005 Yamaha R1. A bike hasn't been made I couldn't wreck, spectacularly, but I'm retired now.

  5. #5
    GTE Pilot blinkngone's Avatar
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    With a little assist from the curb, the Rookie will lift the inside wheel.
    Click image for larger version. 

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    Bikes wrecked-77 Suzuki RM125, 78 Honda Elsinore 250, 81 Honda CB900F, 2000 Kawsaki ZX12R(2), 2001 Honda F4I, 2005 Yamaha R1. A bike hasn't been made I couldn't wreck, spectacularly, but I'm retired now.

  6. #6
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    Well, I did a bit of testing on the 288 GTO suspension, using the jump at the beginning of California stage 3. I found out that the maximum travel can be slightly increased in two ways:
    • Softening the spring rate. The increase is highest at minimum spring rate and ride height, but this is still only ~3 mm increase (spring rate 48 N/mm -> 39 N/mm at 100 mm ride height)
    • Increasing the ride height. The increase is highest at maximum spring rate and ride height, but this is still only ~3 mm increase (ride height 140 mm -> 150 mm at 127 N/mm spring rate)

    Also, the rear springs extended further than the front springs at comparable settings. I assume the rear wheels are heavier.

    Increasing bump stops decreases the travel value on HUD, but this doesn't mean that the wheel is then hanging closer to the wheel well.

    But anyway, I don't think this is particularly useful information with regards to tuning the car. Just interesting to find out.

  7. #7
    GTE Pilot blinkngone's Avatar
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    Cool. I'll check out the 288 GTO. Have you tried the AM GTE yet? It's a blast to drive with the wheel in the air. Silverstone GP is good track to get some lift with this car.
    Bikes wrecked-77 Suzuki RM125, 78 Honda Elsinore 250, 81 Honda CB900F, 2000 Kawsaki ZX12R(2), 2001 Honda F4I, 2005 Yamaha R1. A bike hasn't been made I couldn't wreck, spectacularly, but I'm retired now.

  8. #8
    GTE Pilot blinkngone's Avatar
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    Quote Originally Posted by Jarben View Post


    Well, I did a bit of testing on the 288 GTO suspension, using the jump at the beginning of California stage 3. I found out that the maximum travel can be slightly increased in two ways:
    • Softening the spring rate. The increase is highest at minimum spring rate and ride height, but this is still only ~3 mm increase (spring rate 48 N/mm -> 39 N/mm at 100 mm ride height)
    • Increasing the ride height. The increase is highest at maximum spring rate and ride height, but this is still only ~3 mm increase (ride height 140 mm -> 150 mm at 127 N/mm spring rate)

    Also, the rear springs extended further than the front springs at comparable settings. I assume the rear wheels are heavier.

    Increasing bump stops decreases the travel value on HUD, but this doesn't mean that the wheel is then hanging closer to the wheel well.

    But anyway, I don't think this is particularly useful information with regards to tuning the car. Just interesting to find out.
    Hey, I can't get the 288 GTO to lift it's wheel. Do you have a screenshot of this?
    Bikes wrecked-77 Suzuki RM125, 78 Honda Elsinore 250, 81 Honda CB900F, 2000 Kawsaki ZX12R(2), 2001 Honda F4I, 2005 Yamaha R1. A bike hasn't been made I couldn't wreck, spectacularly, but I'm retired now.

  9. #9
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    It's probably not very common with the default setup, if that's what you tested with (I have a custom one). Anyway, I too have decided this is not really worth sweating over, and it's better to focus on more important handling problems.

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