Tuning guidelines for cars that completely lose the back end?

Discussion in 'GT6 Tuning' started by Eldeorn, Feb 21, 2014.

  1. Eldeorn

    Eldeorn

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    Hi there my fellow GT6 enthusiasts! My first post here even if I have been reading gtplanet.net for a long time. Excellent site I might add.

    Anywho, to the topic: Ive run across a few cars that often tends to completely lose the back end if I touch the gad pedal even the slightest in a corner, or when Im just driving a bit too fast/turning too hard. Mazda RX7 is one of them, and another is the 60's Lotus I got as prize car. When I lose the back end on those cars, it's lost completely and a 180 spin into a wall is expected almost everytime.

    What's the tuning formula to remedy this behavior? I dont mind that cars gets a little twitchy if I drive too hard, but not at the level where it's impossible to recover every time it happens.

    /Cheers
     
  2. twodogsgolden

    twodogsgolden

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    Add about .15-.25 degrees of positive toe and soften the spring rate. Let me know if that helps.
     
  3. Ksquad

    Ksquad

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    Another thing that helps is to lower the anti roll bar on the rear and to add a wing and add rear downforce though that will also add some understeer.
     
  4. SGETI

    SGETI

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  5. Kavey

    Kavey

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    I find that the default starting values for the custom LSD are often set way too high forcing lots of outside rear Tyre traction loss which ultimately forces horrendous spins. Aside from suspension tweaks as above dropping the LSD values can help a lot.
     
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  6. Eldeorn

    Eldeorn

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    Thanks guys. Nice info. Should help me plenty on the way.

    Also, funny that you posted a link that includes the corvette stingray, since that's the car Im racing with this very moment (Nat A american car challenge). Easy to win even with stock tuning, but can definitly be improved.

    Yeah, from what Ive seen from other tunings, they often set it to less than half the defaults. Except in special cases such as the tuning I found for 86GT seasonal. Acc sens on that one is actually at max 60 so the car can slide around the corners better. Crazy values do give gold sometimes :)

    /cheers
     
  7. DolHaus

    DolHaus

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    You need to work out whether you are suffering with weight transfer problems (too soft) or if you are overloading the tyre (too stiff). Weight transfer is a lot more of an issue in gt6, can give you some odd results if you're not looking for it
     
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  8. demonchilde

    demonchilde

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    The above are all good points and advice.

    There is another aspect to tail happy cars though. If you use it properly.
    combining drifting with street racing, throwing the ass end on purpose to cut corners can cut seconds off your overall time, BUT (very huge BUT), this is a very difficult method of driving and will cause many many huge crashes while your learning it. Actually, it will cause crashes even after you have, lol, but those once in a lifetime unbeatable times will also be a result.
    you still have to tune it, and curb the effect a bit, but you'll want to leave a certain amount of it there to achieve the correct amount of slide.
    Good luck, and many many bandaids later, you will hit some unbelievable times. :-)

    Here, I made a post about what I mean by this in my garage;
    https://www.gtplanet.net/forum/thre...o-ford-gt-05-600pp.295123/page-4#post-9375945
     
    Last edited: Feb 22, 2014
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  9. Eldeorn

    Eldeorn

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    After reading a bit of the Motor City tuning guide, it should be fairly easy to spot I hope, by looking at the tyre colors when Power Oversteering happens. Gonna do a few runs later tonight with the RX7 and see if I can get it this bad boy to behave!
     
  10. Eldeorn

    Eldeorn

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    Location:
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    Seems the issue is with weight transfer. As soon as I corner and throttle, the outer rear wheel grips and goes red while the inner doesnt. This is especially bad on curbs. Once that is in motion, the car keeps rotating even if I try to counter it by either steering or letting the throttle go.

    Gonna go back to stock tuning and see how a tighter rear rollbar will affect things. other peoples tunes did not remedy it. Maybe it can't be done?
     
    Last edited: Feb 22, 2014
  11. DolHaus

    DolHaus

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    which car? I'd avoid playing with the roll bars too much, more likely to be the springs. What tyres and what spring rate/dampers are you running?
     
  12. Eldeorn

    Eldeorn

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    Location:
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    Mazda éfini RX-7 Type R (FD) '91
    Sports Hard

    I reverted back to default tuning values for LSD/Suspension, since all changes Ive tried made it worse pretty much.

    Height: 110/110
    Rate: 5.27/5.95 (*EDIT: not 2.95 :p*)
    Compr: 3/3
    Ext: 3/3
    Anti-Roll: 3/3
    Camber: 0/0
    Toe: 0/.20

    LSD: 10/40/20

    Downforce: 0/20

    The car handles great with these settings actually, as long as I don't try and thottle and turn at the same time.
     
    Last edited: Feb 22, 2014
  13. DolHaus

    DolHaus

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    set the lsd to 10/18/12 and see what happens, high acc settings will naturally make the car likely to light up the tires when on power.
    The spring settings seem ok, although the rear springs being stiffer than the front usually leads to oversteer characteristics depending on weight distribution
     
  14. Eldeorn

    Eldeorn

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    Thx, I Modified the LSD as you said, but I couldnt notice much difference though. However, it became clear to me that the main issue might be the springs compression/extension being too low in the rear, so I hardened it quite a bit, added some toe and heightened the rear a tad.

    The car feels alot more forgiving now and can be pushed in the corners. It became less nimble though, and understeer increased a bit. Oh, and inner curbs in high speed corners is still tricky :p

    Height: 110/130
    Rate: 5.30/5.95
    Compr: 3/6
    Extens: 7/4
    Roll: 4/4
    Camber: 0/0
    Toe: .10/.20

    Breaks: 5/5

    LSD: 10/18/12

    Downforce: 0/5

    Ballast: None
     
  15. FussyFez

    FussyFez

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    Ok.

    Whilst my advice may contradict others, it's up to you what you try, and you will know what works for you.

    You are having power oversteer issues with your rx7.

    It has excellent weight distribution. This gives it excellent natural rotation.
    Front dampers could be closer, so 4 comp and 6 ext.
    I would reverse your rear damper to 4 compression and 6 extension. This will keep the weight over the rear whilst braking, and let it settle down under power. Maybe overall slightly stiffer springs, only a kg or so. Also I would up the roll bars a click each to add stability.

    With lsd, basically, if your outside tyre is spinning, lower the accell. A high accell will give understeer when you have full traction, but cause snap oversteer when traction is lost, a low value will cause the inside tyre to spin first, causing oversteer, but a stable predictable oversteer, but your losing acceleration. If you get to the minimum value (5?)raise the Inital until it is remedied. Inital effects both accel and braking so this will cause braking understeer so lower the deccell. A high braking value gives stability, so a lower one induces rotation on the brakes.

    I hope that makes sense. It's all a balance.

    Sorry if I missed it, but wheel or pad?
     
  16. Eldeorn

    Eldeorn

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    Wheel.

    And thanks, gonna try your version :) This is my first real attempt at tuning, but I defenitly need to learn more about the basics before I can manage to get difficult tunes like this one to work properly.
     
  17. DJay Silver

    DJay Silver

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    You seem to have a similar driving style as I do! I love diving into corners, purposely throwing the back end out, and trying keep the pedal to the metal through entire length of it. It's a very fun way of driving! Not to mention that it looks cool on touge battles! :sly: :tup: It will take a lot of trial and error as you say. But once you get the hang of it, BOOOOM! (That's the only word I can explain it with lol)

     
    Last edited: Feb 22, 2014
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  18. Eldeorn

    Eldeorn

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    FussyFez: it's much better! I tweaked it a bit more and added some downforce and raised the back a bit, so now it actually runs like a race car (touring car even). Awesome. As a bonus, I can slide around corners with it if I want, just like the guys above enjoy ;)

    Mazda éfini RX-7 Type R (FD) '91

    Sports: Hard

    530pp
    443 BHP
    1,030 kg

    Aero Kit - Type A
    Generic Wing - Type B
    Fully-Customisable Suspension
    Racing Brake Kit
    Fully-Customisable Transmission
    Fully-Customisable LSD
    Triple-Plate Clutch
    Carbon Propeller Shaft
    Engine Tuning Stage 1
    Sports Computer
    Racing Exhaust
    Isometric Exhaust Manifold
    Catalytic Converter: Sports
    Intake Tuning
    Low RPM Turbo
    Weight Reduction Stage 3
    Carbon Bonnet
    Window Weight Reduction

    Ride Height: 110/140
    Spring Rate: 6.30/7.30
    Compression: 4/4
    Extension: 6/6
    Roll Bars: 5/5
    Camber: 0/0
    Toe: .10/.20
    Brakes: 5/5

    LSD: 10/6/10

    Downforce: 0/25
    Ballast: 0

    /Cheers
     
  19. FussyFez

    FussyFez

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    Glad I could help.

    Good luck.