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Moving the grip under braking

Discussion in 'rFactor 2' started by Sfrost, Jul 5, 2016.

  1. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    Having a problem with most of the default car setups in the game. I find, under braking, the rear end is too twitchy and when I attempt to turn in and trail break to the apex the back end steps out. I know I can move the brake bias and play with the diff settings to help with this but atm I am running , what feels like, very extreme setups ~90% coast and ~67% forward brake bias on the URD GT cars. I have read that stiffening and softening certain things with the suspension can help with the matter but from the testing I have done nothing seems to make much of a difference. Was hoping someone could guide me on suspension changes to move the balance around under braking as well as any specific car and track combos I can try to really notice a difference.

  2. I haven't set up a URD EGT car in awhile, but that does seem a bit forward on the brake bias. You may be trying to compensate for overuse of trail braking, so look at the replays and see if the trail braking is more than, say, 25% pedal.

    To increase front grip on corner entry, reduce front slow bump or increase rear slow rebound. Also have a look at your fast damper settings to make sure the car is not bouncing over bumps rather than holding them, particularly in the rear.

    And lastly, sometimes decreasing brake sensitivity can give you more feel.
  3. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    At the moment with the trail braking, if I don't brake early enough and attempt to turn in for the corner the rear steps out and I end up in a spin, was hoping I could set the car up to do the opposite of just slide out wide as that is less costly than a spin.

    How do you pull up telemetry while watching replays?

    I don't want to increase front end grip while braking, I would like to increase rear end grip. Guessing it is just the opposite then. Is there a range I should be looking to keep values within for the dampers? Driving the Venom GT and Arthur Merlin mostly.
  4. Yeah, you can't fix driver error with setup. All you end up doing is compromising the performance. You might need to learn to avoid late braking, be consistent and get your opponents on the exit.

    No idea about telemetry. It's usually pretty obvious if the suspension isn't holding the road in the replay. Tire marks, tire smoke, and daylight under the tires.

    Right, do the opposite to increase rear grip. No, I don't look to keep damper values inside a range as it's all relative to spring rates and personal taste.
  5. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    Don't quite think you get what I want from the car under braking it seems. I want the front end to lock up first when trail braking. At the moment it is the rear that locks up first resulting in the car spinning. If I can get the front to lock up first the front wheels will lock and the car will just slide wide making it much less costly to make a mistake and giving more confidence to push the car. In other words I am getting too much oversteer when trail braking and I want to change that to a small amount of understeer.

    I meant the telemetry as in brake, throttle steering inputs. Otherwise I can't tell how much brake I am using when trailing. You said I should check the replay to see if I am using more than 25% brake when trail braking.
  6. You're forgetting the role downforce plays and how it forces a compromise. There's more rear downforce than front downforce at speed, so grip will favor the rear to ensure best braking distance. As the car slows down, before turn-in, you have to ease off the brakes (aka regressive braking) and the grip is now favoring the fronts because more downforce has been lost on the rear relative to the front. Thus what stops you best in a straight line from speed will be tail-happy when trailbraking, though somewhat controllable via shock settings because it is a dynamic situation.

    If you move the brake bias more forward to allow heavy trailbraking in an effort to compensate for driver error (not braking soon enough or hard enough), then you'll have a longer braking distance and slower corner speed and wear the front tires more. This isn't to say that the default brake bias is ideal after other adjustments, just that you have to choose your priorities for best lap time and sometimes that requires adjusting the driver rather than the car.

    Also don't forget that incorrect downshifting will spin the car. It's another example of how driver error cannot be fixed with a setup change. Downshift later, turn on autoblip, or manually blip the throttle.

    I bet you're not using full-screen replay otherwise you'd have seen the pedals, steering, rpm, g-force, etc:
    Last edited: Jul 6, 2016
  7. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    I understand this but it still is not helping with the original post of finding the rear end too twitchy and the only solutions I have found are move bias forwards and increase coast. I am trying to avoid moving the bias forward as I know it reduces braking performance, as I said in OP, therefore I want to know what suspension changes I can make to make the rear more stable as at the moment I find it too unstable and twitchy. Driver error is not coming into play here as I am currently braking much early than the AIs braking point and using less braking force as I don't want the rears to lock and result in a spin.

    As I said in OP, I am running 67% forward bias at times as the rear keeps locking under braking, not trail braking, just simple straight line braking. My downshifts aren't the problem because even without engine braking the car will spin.

    If you have any more advice to give on solving the issue, believe me, I am all ears.

    In regards to the replay, where do I go to see replays? At the moment I can only watch the short replays by pressing "R" and even when that is full screen it doesn't show the telemetry.
  8. Original: "I find, under braking, the rear end is too twitchy and when I attempt to turn in and trail break to the apex the back end steps out."

    Now: "at times as the rear keeps locking under braking, not trail braking, just simple straight line braking."

    You may be all ears, but you're not listening to yourself as it seems to me those are contradictory stories. Do you understand why I say that?

    If the rear is braking loose in straight-line braking and you don't want to move the brake bias further forward, then reduce the overall braking pressure. The setting is right below the brake bias adjustment in the garage on the advanced tab.

    Edit: you can also increase rear wing and/or decrease front wing.

    The AI do not use the same tires as humans nor do they drive like humans. Do not compare your braking points to theirs.

    Replays are accessible in two different locations. One location is meant for reviewing saved replays, the other is an extension of the replay window when you're at the track with the results window (Apparently I don't have "R" mapped to view replays because it did nothing when I pressed it).

    Saved replays are available under Options and it looks the same as your normal track view, so you may have to make it Full Screen (see second screenshot):

    Click on "Full Screen" while viewing the "at the track" replay window to see the large VCR controls with pedal info:
    Last edited: Jul 7, 2016
    • Agree Agree x 1
  9. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    That quote about 67% forward bias was in relation to your comment of a more rearward bias improves braking performance, but I didn't expand on it enough, a case of me knowing the situation in my head but not explaining things enough for those that don't. My 1st problem was with the rears locking during straight line braking so I moved the brake bias forward till it got to the point where it did not do that any more, that was the 67%. It somewhat helped with the trail braking issue but the car would still spin out at times. I also then gained the problem of there being a substantial difference in front and rear brake temps. I tried to move the brake bias reward, however this reintroduced the problem of rears locking during straight line braking. The OP was written when I had the straight line braking temporarily fixed but not the brake temps or trail braking. Was hoping to get some guidance aimed at addressing the problem of setting the car up so I could brake hard in a straight line without locking the rears and at the same time be able to trail brake with the knowledge of if I go too far it will be the front that loses grip first not the rear. I could then go back and start moving brake bias rearward and just increase the settings that cause more understeer during braking so I can improve braking perforamance, balance out the temps and not have the car spin when I trail brake. As it stands now I know playing with the diff can help with this goal but atm it is the only option I have as I don't know what does what with the suspension settings, I have just heard playing with the suspension helps.

    I thought about playing with this but was unsure, wanted to know if reducing brake pressure affected the brakes stopping ability.

    In regards to wings, how effective is this as in the low speed corners, wouldn't I too slow for higher wings to provide any benefit? You have mentioned dampers before, but can I do anything with springs, camber, toe, caster etc etc
    Noted for the future, did not know this.
    Thanks for the replay stuff will check it out
  10. Kevin Ryan

    Kevin Ryan
    Premium Member

    It could be down to the fast damper settings in the rear suspension. Try decreasing the fast bump in the rear. Also, it doesn't seem liked you played around with brake pressure yet...
    I don't have the EGT mod yet but I'll be trying it very soon, hopefully get back to you with more info.
  11. Wings affect higher speeds. If you're having troubles braking in a straight line, they affect grip at the beginning and are a compromise for what's needed through faster corners. They have little effect in slow corners, below 90 mph.

    Springs/swaybars are for static balance and that's why you set the spring rate on a skidpad. Shocks are for dynamic balance, to control the rate of weight transfer and avoid bad oscillations.

    Camber closer to zero will improve straight line grip.

    Front toe-in increases braking stability. Front toe-out increases steering response, but makes braking darty. The stiffer your suspension, the more you can go towards toe-out until braking becomes too darty. Rear toe should never be toe-out and generally you don't use it for steering effects.

    Caster has no effect on braking.

    rF2 has realroad, so what is ideal when your session starts might not be ideal by the end of the race. Figure out the compromise that works for you and learn to adapt to the required driving style.
    Last edited: Jul 7, 2016
  12. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    Any way to counter balance the understeer caused by running higher rear wing?

    Not sure what you mean by static and dynamic balance here, any chance you could explain? Also, how would I go about setting up these on a skidpad? Does rfactor have a skidpad?

    Thanks for the rest of the stuff will give it a go when I get the chance.
  13. LOL... do you not know that aerodynamics work on a cubic law, that downforce is proportional to the speed cubed? If you have a massive chassis understeer (non-aerodynamic), then trying to balance it with only aerodynamics works at only a small range of speeds above ~90 mph. What happens when you go below 90 mph? You have no help from the aerodynamics.

    Static = unchanging, like the steady-state cornering with constant throttle to maintain speed, as on a skidpad
    Dynamic = changing, where there is braking and acceleration

    It's a really good idea to dig through the official ISI forums (or google)...
  14. I think the Viper is generally a hard to drive car, at least with the default setup. One of the reasons might be the drag torque caused by the big V10 engine. But i have to say i don´t have such massive problems as you describe.
    Not sure about your brake balance, with 67 at the front you may overheat the front brakes and you get then much more braketorque at the rear at the end of the braking as the front brakes dont work in their optimum temperature range.
    Last edited: Jul 8, 2016
  15. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    Yes, I meant for the high speed corners obviously not the low speed, thought that one would be fairly obvious lol.

    So if I am having mid corner understeer or oversteer I should play with springs and sway bars and if I am having oversteer or understeer on corner entry/exit play with dampers?

    I am definitely getting overheating brakes as my fronts are well over 700 by the end of the big braking zones while the rears are sitting down at 300, why I really want to sort out the twitchy rear end braking issue :p
  16. Suggest you to try to increase the preload-value on the differential settings up to max value (you can stay in the first step with power and coast@default values 25%/50%). The differential preload value can be described simplified as the minium differential setting while the power and coast values are maximum settings (@Emery: feel free to correct my explanation ;) ). It helped me a lot to keep the Viper more stable.

    Also go back with the brake bias to a point where the front brakes dont get much about 600°C max.

    And try the S8 tires instead of the S7 tires, they should have the same grip, but work at different temperatures. Driving actually Mosport at about 25 degrees temperature and with the S8-tire the viper is less twitchy.
    Overall i have to say even with this settings the viper is a nervous car, much more then the corvette. It needs to be driven really smooth.
    Last edited: Jul 10, 2016
  17. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    Thanks for this, will give it a go when I get the chance :)
  18. Sfrost

    FFT Corse driver #116 Aston Martin v8 Vantage Premium Member

    This was a massive help with the cars, they feel so much better and I feel I can actually attack the corner, thanks :)
  19. I´m happy i was able to help :)