Page 13 of 15 FirstFirst ... 31112131415 LastLast
Results 121 to 130 of 144

Thread: [Magic inside!] Need Help With Differentials

  1. #121
    WMD Member M4MKey's Avatar
    Join Date
    Oct 2011
    Location
    France
    Posts
    268
    what ? So by less locking on the accel diff, you have less powersteering ? That' doesn't make any sense. I agree with the first and final part of your post. Higher angle = less locking. But then Higher angles on the accel diff makes more powersteering
    Intel i7 4770K o/c @ 3.9Ghz | Gigabyte 1080ti Xtreme | 16Go DDR3 17000 // TS-PC Racer with fanatec ClubSports Pedals

  2. #122
    Kart Driver
    Join Date
    Nov 2017
    Posts
    43
    Platform
    PC
    Quote Originally Posted by M4MKey View Post
    what ? So by less locking on the accel diff, you have less powersteering ? That' doesn't make any sense. I agree with the first and final part of your post. Higher angle = less locking. But then Higher angles on the accel diff makes more powersteering
    less locking = less power over is actually very logical, because the axle "locks" it self later, allowing for more power being sent to the unloaded wheel.
    Power steering is an altogether different thing.
    The following user likes this Post: F1_Racer68


  3. #123
    Kart Driver 2010 Synergy Camaro's Avatar
    Join Date
    Sep 2017
    Location
    Central Time Zone
    Posts
    56
    Platform
    PC
    Quote Originally Posted by Jussi Karjalainen View Post
    Also good to know is that higher ramp angle = less locking, as the help text denotes. So in a very very simplified form if you want to avoid power oversteer, increase the power ramp angle, and if you want to avoid lift off oversteer, decrease coast ramp angle.
    Thank You Jussi. I also appreciate your suspension calculator very much. I am able to use and understand it just fine. Hopefully, after playing around with the differential calculator I will get the hang of it in time also.
    MOBO: MSI B250 PC Mate CPU: i5 7500 Memory: DDR4-2400 2X8GB
    GPU: NVDIA GeForce GTX 1060 OS: Windows 10 Creator Ver 1709 Display: 1080P. Wheel: Logitech G29 with Wheelstand Pro V2.
    The following user likes this Post: Jussi Karjalainen


  4. #124
    Handling QA Lead Jussi Karjalainen's Avatar
    Join Date
    Nov 2016
    Posts
    351
    Platform
    PC
    Quote Originally Posted by M4MKey View Post
    what ? So by less locking on the accel diff, you have less powersteering ? That' doesn't make any sense. I agree with the first and final part of your post. Higher angle = less locking. But then Higher angles on the accel diff makes more powersteering
    More accel locking increases power oversteer for the same reason why drift cars use aggressive accel locking (or even spooled diffs) instead of open diffs. =)

    If your diff is open, the torque distribution is 50:50, so the amount of power/torque you can put down is limited by the tyre with the lowest grip. If one tyre has only enough grip to manage 100 Nm of torque without slipping, you can't send more than 100 Nm to the other tyre either, for a total of 200 Nm going to the ground and doing useful work, even if it could handle 1000 Nm of torque.

    What locking does is effectively increase the amount of torque you can send to the side with more grip. If you were in the situation above but had 100 Nm of preload, you could send 100 Nm to the tyre with less grip and 100 Nm to the tyre with more grip due to the 50:50 torque split, but also 100 Nm extra on the tyre with more grip due to the preload, for a total of 300 Nm of torque going to the ground. Accel locking works in the same way basically, the main difference between it and preload is that preload is always the same, whereas accel (and decel) locking varies by how much torque is coming to the diff (so on 100% throttle you get more locking than on 50% throttle, in low gears you get more locking than in high gears, etc.).

    So, locking allows you to put extra torque/power on the tyre with more grip. Before you were limited by the tyre with less grip, but locking enables you to overpower both tyres at the same time. This causes oversteer. =)

    And on top of that there's the potential for a yawing torque to be applied on the car with more locking. If you have lots of accel locking, maybe even a spooled diff, and you're cornering hard, your outside tyre will have way higher grip potential than your inside tyre. If you mash the throttle, most of the thrust pushing the car forwards will be coming from the outside rear tyre. That tyre is not in the center of the car, so as it pushes the car it will also try to rotate it (just like if you push a box forwards near it's edge it'll spin, but if you push it in the center it'll go straight). That can add an extra tendency towards oversteer. =)

    Here's a showcase of a car with 90 degree accel ramp and no other locking, vs. the same car with 20 degree accel ramp:



    EDIT: At low loads where you're not really straining against the limitations of the tyres (for example turning into a parking spot, which requires lots of differentiation but isn't really putting the tyres at their limits of grip under normal conditions) lots of locking can indeed cause understeer, but when pushing to the edge it becomes about the difference between spinning one wheel vs. spinning both. With locking you'll always want to rotate both wheels, one can't turn independently, so if you're going to get wheelspin, you'll get it on both driven wheels.
    The following 7 users likes this Post: F1_Racer68, Jetsun, M. -VIPER- Morgan, M4MKey, PostBox981, rich1e I, Sessionerror


  5. #125
    WMD Member PostBox981's Avatar
    Join Date
    May 2015
    Location
    Close to Bremen
    Posts
    1,049
    Platform
    PC
    Thanks Jussi for spending so much time in this thread. I am sure I still donŽt get all my diff settings right but with every single post of yours the technology is getting a little clearer for me. Without all your help I guess some 95% of us would be completely lost in the dark.
    CPU: Intel Core i7 5820K@4.2 GHz | Mainboard: MSI X99-A SLI Plus | RAM: 16GB DDR4-2400 | GPU: nVidia Geforce GTX 1080 ti Founders Edition @+100 MHz | Oculus Rift CV1 | Operating System: Windows 10 Home x64 | Controls: Fanatec ClubSport Wheel Base V2.5 / Forza Motorsport Wheel / Clubsport Pedals V3 / ClubSport Shifter SQ

    In case youŽre looking for some clean and relaxed online racing, take a look at this: www.malzbierbude.de
    The following 3 users likes this Post: Jetsun, M4MKey, ShneebnaMRR108


  6. #126
    Kart Driver
    Join Date
    Jan 2018
    Posts
    26
    Platform
    PC
    So I need low values to prevent over/understeer? Thought it was the other way around.

  7. #127
    Handling QA Lead Jussi Karjalainen's Avatar
    Join Date
    Nov 2016
    Posts
    351
    Platform
    PC
    Quote Originally Posted by Max Torque View Post
    So I need low values to prevent over/understeer? Thought it was the other way around.
    Low coast ramp angle = more deceleration locking = more understeer

    Low power ramp angle = more acceleration locking = more power oversteer (when a car is capable of breaking traction at least)
    The following 4 users likes this Post: F1_Racer68, Major Epidemic, PostBox981, senna94f1


  8. #128
    Kart Driver
    Join Date
    Jan 2018
    Posts
    26
    Platform
    PC
    Quote Originally Posted by Jussi Karjalainen View Post
    Low coast ramp angle = more deceleration locking = more understeer

    Low power ramp angle = more acceleration locking = more power oversteer (when a car is capable of breaking traction at least)
    Ah, ok, I confused "more lock" with "higher value". But "higher value" means less lock.
    The following 2 users likes this Post: F1_Racer68, Jussi Karjalainen


  9. #129
    GT5 Pilot Jezza819's Avatar
    Join Date
    May 2015
    Location
    Alabama
    Posts
    1,105
    Platform
    XBOX1 X
    I've just started to try and see if I can make diff changes to fix the cars that I'm having trouble with spinouts either off throttle or on. It doesn't seem to matter. I actually think I could spin one out if it were sitting totally still. But in looking at the diff settings the power and coast doesn't seem to have as big of a range as preload does. Does it make sense to see what the range of power and coast are and set them right in the middle, see what that does, then start going up or down on each and see what happens? I forget which car I was looking at but the low end of preload was -100 and it went all the way up to 400. Needless to say I put it right back where it started and didn't touch it.
    Xbox 1 X - Fanatec CSW V2 wheel - Fanatec V3 pedals

  10. #130
    Rookie
    Join Date
    May 2018
    Location
    Germany
    Posts
    4
    Platform
    PS4 Pro
    As this is my first post in this forum I'd like to say hello to everybody first. Having read through different topics here I really appreciate the helpfullness among each other in general and especially the patient manner of Jussi's explanations...

    I've been enjoying PC2 for some weeks now and found myself being best with lsd switched off in formula rookie. With lsd on I would spin out midcorners pretty much as Jezza describes it. Now that I've proceeded to Formula C I wanted to take advantage of the fully adjustable clutch lsd but again I was u-turning unintentionally rather often. Switching off the lsd I was fine again. So I tried to figure out which detail of the setup was causing me trouble starting with clutch lsd switched ON but power and coast ramp to 90 degrees and preload to zero Nm. At least this is what I thought would neutralize the lsd. There still were side-steps at the rear axle I didn't encounter with lsd off. Going all the way down too -100Nm preload finally made it feel like completely switched off. From that point I could start playing with the ramp angles and creating a setup making me confident to push harder (at least within my rather limited skills...).

    So there appear some more questions to the experienced lsd tuners.

    1) Do I need to calibrate that negative preload in order to reduce the base friction of the clutch plates? If yes: how much base lock does the clutch lsd have? -100Nm seems a bit much I have to admit.
    2) especially at Jussi: as drivetrain torque changes sign in transitions from power to coast and vice versa does this also apply to preload?

    Thanks in advance and have a nice week,

    Tim
    The following user likes this Post: Jezza819


Similar Threads

  1. Where Do I Get AI's Magic Tires?
    By Quatzu in forum General Discussion
    Replies: 16
    Last Post: 06-06-2017, 01:39

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •