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General Setup of the FR 3.5

Discussion in 'Presto GP' started by jego, Oct 4, 2016.

  1. jego

    jego
    Premium Member

    Just recently I found that ISI states that the default setup of the car is more or less what you would expect the car to be setup in real life.
    Also I found that they provide an easier setup. Both those however are completely different to the ones that get posted here.

    David's and especially Martin's setups are super soft. Everything regarding the springs is at the lowest setting and also the car height is very low.

    I am no expert at all but from what I have read such a setup should actually behave very unstable, as high downforce in fast sectors would push the car very low and once slowing down the springs would open up making the car feel and react very different.

    Am I misunderstanding something here?
    Also how is your approach towards making a setup?
    I am using a 21 step guide made for GTR2.
     
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  2. Sry, no time for a comprehensive answer, but here are some statements:

    The softer the suspension the more grip you have, but like you wrote, the harder the handling can be.
    Also the lower the car the better the handling, but the possibility to touch the track is higher, and then you have a really bad handling (e.g. on curbs, ...).

    I`m also no expert, but I think it is the best way to find out how the car reacts for your own.
    Try to take a default setup and change the setup step by step and look how it feels.
    This and read all setup guides you find, then you will find you way.

    Basicly I understand the background of the settings.
    And the result of the changes are often how I wanted to modify the handling of the car.
    But also often then I`m not faster :D
    So my secret procedure to create a setup is often trail&error :D

    Also an important point is that the setup has to fit to the driver respectively to the driving style.
    E.g. I never ever was able to do a PB with a setup from David, but we all know, he`s damn fast, and so they can`t be bad setups ...
    ... or the setups are bad and he`s a much much more faster driver ... hopefully not :D:D:D

    And finally: a setup is always a compromise :geek:

    I hope I was able to help you :)

    Cyas
    Martin
     
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    • Agree Agree x 1
  3. ... and I use this very useful PlugIn from our Cosimo :)
    Martin
     
    • Agree Agree x 1
  4. jego

    jego
    Premium Member

    Yea thanks for your input. I guess it just comes with experience to know how to do this properly.
    My main problem is probably sticking with small changes. I often catch me thinking, well this one corner has too much oversteer and I end up changing 3 settings at once to see if this fixes anything :p
     
  5. Suspension

    I'm gonna go ahead and spoil something for you... Open wheel car suspension sucks, always. And it's as simple as that. :p The best open wheel suspension in this day and age is actually just the least terrible. It's pretty much always a compromise between suspension and aero where the suspension ends up much lower on the priorities list.

    Have you ever heard about how harder suspension is worse for handling, and ideally you want it as soft as can be in all cars? Open wheel cars basically live in the 'too hard' region of that scale all the time. You'll find there's more change in suspension behaviour from tire pressure changes than with suspension rate changes. So when following setup guides on the internet, try applying the advice they give for springs to tire pressures. Too high or too low and you lose out, but small adjustments following those principles are very helpful.

    Also, remember how I said aerodynamics ends up being higher priority than suspension? For every suspension & tire pressure setup, there is a sweet spot in the ride heights. So just try raising/lowering the front or rear (separately) and see what happens. You'll know when you find the sweet spot because much faster lap times will come with barely any effort as a driver. :D

    Differential

    This is the most style dependent part of the setup IMO. So if you ever have trouble using someone else's setup, this should be the first thing you look at. It's probably the single biggest part of controlling the understeer-oversteer scale of handling in a setup in relation to throttle input. So when we all think a car should oversteer/understeer more/less in reaction to what's happening with the throttle? We look at the diff.

    It's worth remembering that not all cars lift their inside driven wheel enough that an open diff will spin all its power away on there. Pretty much all single seat race cars built after 1980 are like that. I think people would be surprised how well a modern open wheel car can drive with an open diff. Having a limited slip diff in cars like this is much less urgent, though it's still preferable. Hence they all do it. :)

    Goal #1 of the diff is to maximise the engine torque output to the wheels so that you use all of the longitudinal grip. Too much locking, and the inside wheel spins too fast, causing wear. Too little locking, and the inside does nothing and you limit yourself to the longitudinal grip of the outside wheel only (this also causes insane oversteer when accelerating). Again, there's a sweet spot here which gives optimal corner exits, and deviating too much from it won't do any good. This is what the 'power' setting is in the FR35.

    The 'coast' setting is the same thing, but when we have negative torque going into the wheels... Such as engine braking. And this is probably the most important part of driver comfort of all. If you want more stability at initial turn-in, more coast-side locking will probably do it. If you want more rapid initial turn-in, less coast-side locking will help. And reducing the 'brake map' setting in the setup will make these characteristics more pronounced.
     
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  6. Blauweke

    Blauweke
    Premium Member

    Here's a question: what does the rear roll centre do, and how can you tell what the diffirent settinsg actually are.
     
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  7. David Turnbull

    David Turnbull
    PrestoGP Veteran

    Heres some info I have on roll centres that I keep handy for anytime I need to change them, but tbh thats very rarely I stick to what I have had for a long time and it usually serves me well everywhere with minimal changes.
     

    Attached Files:

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  8. Thanks for this discussion April.

    This may seem like a question with an obvious answer, however, I have never found it totally clear.

    One point that always has me perplexed in differential discussions, is reference to "more" power setting(or "more" coast setting) vs. "Less" power setting(or "less" coast setting). Is "more" a bigger value or a smaller value? What does "more" mean? Bigger value or bigger understeer(more rear wheel grip due to less wheel spin through the rear wheel combination)? Every once in while there are parameters where the terms "more" and "less" do not necessarily refer to a bigger or a small value depending on what you are referring too. Perhaps it is because "more" oversteer can also be thought of as "less" understeer! It has been my perception that a bigger value of "power" leads to more lockup which can lead to understeer on acceleration on corner exit. Similarly a smaller value of coast leads to more(?) lockup and oversteer on braking and turnin?

    I'm not sure what "more" or "less" means in this dynamic.

    Could you comment on your points above in terms what you mean by "more" and "less" relative to lockup and oversteer/understeer?

    Example:

    More/power = bigger/value = more/understeer = less/understeer on corner exit acceleration
    Less/ power = smaller/value = less/understeer = more/oversteer on corner exit acceleration
    More/coast = ?/Value = ?/oversteer = ?/understeer on corner entry
    Less/coast = ?/Value = ?/oversteer = ?/understeer on corner entry

    Appreciate clarification of your choice of words.

    Many thanks

    Stephen
     
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  9. Hey Stephen, long time no see :D

    When I say more when talking about the diff, I mean larger numbers in the setup screen. Those larger numbers mean the driven wheels are locked together more in the situations they affect.

    It usually mainfests as understeer/oversteer because of how it applies yaw forces to the car. In an extreme case where 100% of the torque goes to the RL wheel, that puts the acceleration force as far off centre from the car as possible. And it will also push to yaw the car to the right at the same time as accelerate. The more that happens, it manifests as oversteer to the driver. When you start locking the wheels together (increasing these numbers in the setup screen) it starts redirecting torque to the other wheel. So if you have 75% torque on the RL and 25% on the RR, the yaw force causing the car to oversteer has reduced because the 75% is partially cancelled out by the 25% opposite. And in a more extreme situation where the torque is split 50:50 between the rears, that acceleration force is placed directly in line with the car's CoM and there will be no yaw force at all from that (as is the case with locked diffs).

    The same happens in the opposite direction when decelerating due to engine back torque, so is more pronounced when you reduce the 'brake map' number in the setup.

    I don't normally like reducing setup changes down to tables of 'understeer/oversteer' scenarios, since it can transfer badly between different cars. But I guess something like this should hold true for the FR35 and other modern single seaters.

    If car understeers when accelerating, try a smaller power side diff number
    If car oversteers when accelerating, try a larger power side diff number
    If car understeers when decelerating, try a smaller coast side diff number
    If car oversteers when decelerating, try a larger coast side diff number
    If the changes above seem to do nothing, use a much lower preload number and try again
    If car understeers everywhere, try a lower preload number
    If car is not progressive and 'snappy' when responding to pedal inputs, try a much lower preload number
    If there are rapid yaw actions during uneven/irregular loading and forces (like running on rumble strips), try a higher preload number

    (As you can see, I like the theory that preload should be as low as possible in the FR35 :p I'm usually way below the default on preload in my setups for this car)

    Note that I've said accelerating/decelerating instead of entry/exit. In corners where you're accelerating from entry to exit, coast side is irrelevant (IE Dunlop @ Suzuka) and it's all about the power side. Inversely, in corners where you're decelerating all the way through, coast side is the only one we're interested in.
     
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  10. Thanks April

    Your summary helps, I was just trying to confirm the adjustment direction.

    cheers