Flatspots

Discussion in 'General Discussion' started by PLAYLIFE, Jun 17, 2013.

  1. Noel Hibbard

    Noel Hibbard Registered

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    I could be wrong but I think the flatspotting vibrates more when turning because it is unloading the tire with the flatspot. For example, say your RL tire is flatspoted. You will probably feel it more as you turn left because the FL will have less load on it.

    My experience with flatspots so far has been that I mostly feel it in turns but eventually as it gets worse I start to feel it on the straights too.
     
  2. speed1

    speed1 Banned

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    Depending on the situation. While any powered unbalanced free rotation part without load is able to cause higher vibrations, in this case the inner wheel is on a non-driven axle and has at the same time a lower rpm in the comparison to the outter wheel while still under load and keeping stronger contact which is the main cause for this. The loaded tire with the flat spot will have a greater impact on mechanical parts while the unloaded could cause vibrations as well in a diff frequenz.
     
  3. Spinelli

    Spinelli Banned

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    I cant confirm for sure, as I havent played RF2 in a while, but if you are feeling it, but not on the straights, then it is probably due to the Logitech G25's/G27's stupid design of having FFB pretty much turned off when the wheel is straight. Its a confirmed intentional thing, straight from logitech in order to avoid the 2 motors fighting and destroying eachother when the wheel is centred.

    I learned this the hard way when I spent lots of money on a new one, coming from the much less espensive black Momo Racing wheel, to the G25. I even went through the hassle of returning it once because I thought it was faulty due to the problem. The FFB off in the centre meant, well, no FFB until you turned a few degrees each way. This made judging lockup, and all sorts of grip and behaviour characteristics through FFB while your wheel was still straight or just about straight pretty much impossible, and therefore really hurt my ability to brake at the absolute, absolute latest possible, and the general consistency as well.

    Tried to get used to it for over 2 freaking years, but without the FFB, there is only so much you can get used to from visual and sound cues, especially when trying to threshold brake and trying to feel all sorts of stuff under braking and initial turn in.

    When I found out the G27 still had this issue I just said screw it. I got a cable driven Red Momo Force, sure its not as powerfull or as fast as the G25, it doesnt have all the rotation either (only 270 degrees), but the FFB always works, I dont have to turn the wheel left or right to enable the FFB. Not to mention the Momo wheel is a much thicker true to life race car wheel, unlike the thin dinky feeling G25's, but thats a different issue.
     
  4. PLAYLIFE

    PLAYLIFE Member

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    Thanks for the replies and further testing gents, it sounds like point number (1) in the original post is a G25/27 shortcoming which cane be offset by adjusting the filter setting.

    Would be nice to get confirmation with regards to point (2) if it's implemented, and if so how they actually achieve it. And if not, if there's any intention to do it.

    As I said earlier, I'm quite impressed with what we have already :D
     
  5. vittorio

    vittorio Registered

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    I can certainly feel the flatspot on straights very pronounced on the CSR-E. As Minibull and Spinelli already said, the G25/G27 are known to have a deadzone (unlinearity) around center. You can lessen this effect by setting "Overall Effects Strength" to 107% in the Logitech G25/G27 settings.
     
  6. DrR1pper

    DrR1pper Registered

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    I'm certainly no expert but my guess would be yes? Any flatspots (front or rear) will continually upset the cars dynamic weight distribution. Changing weight distributions through a corner will dynamically affect/alter the cars rotation rate throughout that turn (i.e. car can't achieve rotational equilibrium). In the same way that when you turn the steering wheel you feel a self-correcting force caused by the front wheels trying to straighten the car, there will be an additional dynamic correcting force acting on the steering wheel caused by the changing rotation rate caused by the changing weight balance caused by the flatspots.
     
  7. DurgeDriven

    DurgeDriven Banned

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    I wondered what you were doing line locking around Lesmos.

    Thought you went crazy and would have to shoot you. p


    Remember we had x7 tyre wear as well.


    Seems to me flatspots are canned effect like build up, it is a nice touch though.
     
  8. kaptainkremmen

    kaptainkremmen Registered

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    I would say the forces felt from rears would be pretty small. It's hard for your brain to filter out what should be felt as a turning force and what should just be a vibration.

    On the fronts the effect is dramatic, the contact patch, slip angles, load on the tyre etc means the tyres feel quite large turning forces when the flat spot comes around.

    With the rears they will affect the balance of the car slightly (you'll certainly lose grip) and perhaps you would feel something in the wheel but in real life most of what you feel is just a bump in the chassis/vehicle.
     
  9. Reprobator

    Reprobator Registered

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    I tried it this morning and feeled very well the effect even in staight line (t500 rs here) and with the f3 i could see that we can have more than 1 flat spot on the same tire (3 tire lock up and three flat spot and all a bit different depending on the distance and speed of the lock up )
     
  10. speed1

    speed1 Banned

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    I'm not sure whether I have understood everything correctly but yes the imbalance causes irregular rotation, rocking vehicle body and upsets the balance while a unbalance by the rear axle can causes a wiggly driving line. This will be felt in the steering as well regardless of whether a vibration is passed through the body or the disturbed front axle by a dynamic trail.

    I have asked myself out of curiosity whether it is simulated and how. If the unbalance is be treated actually dynamically as a rotating unbalance and or could it be possible to transfer it to the body or the steering system from the rear axle as well.
     
  11. Guy Moulton

    Guy Moulton Registered

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    If you have ever had a wheel on your car that was out of balance, you know that a wheel on the front axle feels different than a wheel on the rear axle.

    -On the front axle you feel the shake through the wheel itself and in your hands. Anytime your weight is forward (in braking) the vibration gets more intense.

    -On the rear axle you feel it much less and you feel it in your seat and also in the wheel but not as bad. When you accelerate the vibration gets a little worse. In sim racing, ALL your FFB comes through the wheel so that is where you are going to feel it regardless of where it should come from.

    Front tire flatpots area lot more common and a lot worse because the weight shifting in braking and also because most braking is done with the front wheels where your brake is biased toward. I can't even understand how anyone could flat spot the rears and not the fronts in a properly set up car. In rF2 you can see the flat spot on open wheel cars.
     
  12. Marc Collins

    Marc Collins Registered

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    Sadly it is a G shortcoming. In an otherwise great wheel, the lack of FFB when pointed straight is a deal killer for me. Not sure any filtering or settings can cure it because it's part of the design of the wheel and drivers (same issue in every sim). Only solution for me was to switch to a Fanatec.
     
  13. Barf Factor

    Barf Factor Registered

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    That's what I thought too, but some people said they were able to get rid of the g25/g27 ffb deadzone or didn't experience the ffb deadzone in certain games. Today I tried experimenting some more, adjusting "Overall Effects Strength" in the logitech profiler 'Global device settings'. Turning it too high caused the wheel to oscillate violently, but at 120% my wheel behaves and there is force feedback in the centre. I can now feel flatspots even when the wheel is dead straight.

    Does this work for anyone else? Maybe the exact percentage varies from wheel to wheel, my motors are probably a bit worn out.
     
  14. MarcG

    MarcG Registered

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    the more percentage the more clipping you might get which is'nt a good thing as it's not relating to the true FFB of the situation...or so i've read! I've got my overall strength on 107% as I've seen on various forums that's the best setting for a G25, and as above with Filtering on 4 I can feel Flat Spots in a straight line so it's fine for me. There is a deadzone but not enough to worry me personally but FFB is all about personal taste, worth fiddling with the settings to find what suits you and go with that.
     
  15. Barf Factor

    Barf Factor Registered

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    Yes you are right about ffb clipping, I will try fiddling with the settings some more
     
  16. Lazza

    Lazza Registered

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    If the rF2 plugin interface supported FFB (last time I tried it, it didn't) a plugin could be made to amplify the FFB around centre and leave it alone elsewhere. That would work in rF1, not sure it produces enough FFB at centre to make it worthwhile though.
     
  17. clevytr6

    clevytr6 Registered

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    When going in a straight line on a smooth surface in my real car, I get no FFB as no forces are acting on the steering. A bumpy road IRL, like Spa 66 , plenty of forces. My first build G25 still working great. Turn up your car specific FFB multiplier to 2.0 while in game under controls.
     
  18. PLAYLIFE

    PLAYLIFE Member

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    MarcG, if you have the time could you post your Logitech profiler FFB settings as well as in-game FFB settings?
     
  19. MarcG

    MarcG Registered

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    Yep will do later for Logitech (at work), as for the game it's all default bar the filtering which is level 4 in game.
     
  20. MarcG

    MarcG Registered

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    Logitech:

    Deg of Rot 900
    Overall 107%
    Spring 0%
    Damper 10%
    Centre Spring unticked and 0%
    Allow Game to Adjust ticked

    IIRC those were recommended settings from Kunos for AC and G25, I've just left them the same as I'm not one to fiddle with FFB too much, probably way too weak for many people but it's fine for me!
     

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