Struggling with understeer- MP4-12C @ Bathurst

Discussion in 'GT6 Tuning' started by thesrdic, Nov 21, 2014.

  1. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Hi all.
    I'm currently using an MP4-12C in a private series, but really struggling now the series has moved to Bathurst for round 2. For the first round (Daytona Rd) I managed to win and loved the feel of the car but at Bathurst I'm understeering all over the shop, especially from Griffins to Skyline. Hell corner (t1) and the last turn are a bit of a problem but I'm putting that down to not knowing my braking point for now.

    I've tried making the springs and dampers a bit lower and while it's helped a tad it's not done near enough. I'm currently on a 2:05 but everyone else in the class is in the 2:02/2:03 region (I'd like to get to 2:03).

    So the setup. First I'll list the parts that can't be changed as part of the regs.
    Change Oil, Increase Rigidity.
    Engine Turing stage 3, Sports computer, racing exhaust, isometric exhaust manifold, catalytic converter- sports, intake tuning. Power limiter at 63.9% = 550BHP. (No turbo)
    Weight Reduction stage 2, Carbon bonnet, window weight reduction. Balast 161kg at -50 (50:50) = 1320kg. Racing brakes, carbon prop shaft, triple plate clutch.
    I currently have aero at max (100) with a custom rear wing.

    My current suspension setup is a slight modification on Praiano's, it was the best of the various base tunes I found on GTP- I'm not great at tuning from scratch.

    80 - 85
    9 - 14
    4 - 5
    6 - 6
    2 - 2
    2.0 - 2.0
    -0.08 - 0
    brakes 5 - 7

    Max speed 224
    1st 3.967
    2nd 2.750
    3rd 2.115
    4th 1.671
    5th 1.373
    6th 1.174
    7th 1.029

    Note- I'm also finding my car bounces around off/at the rev limited at the top of 3rd coming out of some corners, any advice here? Is my 3rd gear just too long?

    Diff 10 / 10 / 30.

    I'm reasonably happy with braking, I'm both the fastest by a couple of mph and latest braker in my class into The Chase.

    If anyone had any thoughts or was even prepared to do a little testing for me then I'd be very grateful. I'm on DS3 with only ABS 1 and limited to RH tyres per series rules.
     
    Last edited: Nov 21, 2014
  2. Bowtie-muscle

    Bowtie-muscle

    Messages:
    3,997
    Location:
    United States
    I do not have the time top check nor have I had, but, from looking at the setup I would suggest trying a few things.
    Try lowing rear downforce to 90 or 85. Lower front camber to 1.0. Try lowing front spring rate to 8.0. Do these one at a time and see if they help. I built a tune at Silverstone as was told it lacked fun and tended to push mid corner, but when the tune was taken to Bathhurst it felt totally different. Small changes 1 at a time to see gains and losses are the best approach in my opinion. Also try lowering third ten to 15 clicks if it is hitting the limiter.
     
    cbarbosa and Thorin Cain like this.
  3. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Ok thanks a lot I'll have a go in a bit.
    Would removing aero help up the hill at all?
    I'm already the fastest in a straight line so I don't really need to remove it for straight line speed. Still I guess if it gets me enough time it could be worth it.
     
  4. Bowtie-muscle

    Bowtie-muscle

    Messages:
    3,997
    Location:
    United States
    You can try it but be warned, it will change the handling more than just lowering downforce.
     
  5. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    In what way?
     
  6. Bowtie-muscle

    Bowtie-muscle

    Messages:
    3,997
    Location:
    United States
    Likely loosen up the rear.
     
  7. cbarbosa

    cbarbosa Premium

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    4,010
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    If I may, don't remove aero, put to minimum (believe 5). You will notice the difference... :)
     
    Bowtie-muscle likes this.
  8. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Ok thanks guys.
    cbarbosa by removing aero I just meant taking downforce off, not the wing :)
     
  9. cbarbosa

    cbarbosa Premium

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    4,010
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    :tup: Ok, my bad... :)
     
  10. Harry6784

    Harry6784

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    1,591
    Location:
    United States
    First, lose the camber, it actually makes you slower :lol:

    Secondly try to raise your front ride height/lower rear ride height to give your car better turn in and a more "loose" feel. Then fine tune with your LSD, try running less deceleration LSD :tup:
     
  11. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Thanks all, the race was Saturday and I managed to find a better setup and improve by a second or so. Turns out lower ing the rear spring stiffness was the key one. The others helped a tad but not as much. Onto Silverstone now so a much flatter track!
     
  12. Bowtie-muscle

    Bowtie-muscle

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    3,997
    Location:
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  13. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Thanks I'll have a look when I do some testing for round 3 tomorrow. (We missed last Saturday.)
     
  14. thesrdic

    thesrdic

    Messages:
    889
    Location:
    England
    Thanks your setup has found me 6 tenths or so. I'm still a bit understeery though, I think I need a setup built specifically for this weight (WR2 +CB+WiR +161kg at -50 - 1320kg @ 50:50) though.