Tuning to reduce lift-off oversteer

Discussion in 'Gran Turismo PSP' started by peterjford, Nov 1, 2009.

  1. NickGuy

    NickGuy

    Messages:
    91
    that audi r8 is a joke =(
     
  2. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    I'm sorry for my rude tone last night, I was tired, I apologize.

    It manipulates How fast and where the weight is transferred to, but doesn't change the total amount being transferred. This is the secondary function of the springs, first being to maintaining the contact patch of the tires. The Secondary (or possibly third) is to manipulate how fast the W/T occurs & IN A CORNER where the weight is transferred to being front or rear. When tuning the amount of weight transfer laterally (Front vs rear in a corner) stiffening the springs is frowned upon because of the affects it has on the springs primary function, you can tune it there to some degree, but tuning the sway bars is more the direction to go (too bad we can't in GT PSP) It's still the same amount being transferred regardless, but the amount Front Vs rear and how fast is altered.

    Stiffer springs up front (or too stiff of a front sway bar) in a corner usually equates to the weight transferring to the front faster then the rear & more Front vs rear, the result is the front will have less traction then the rear. Then a car with a Stiffer Rear spring set up (or too stiff of a rear sway bar) Vs Front, in a corner the rear will have reduced traction.

    So his solution is to cause the rear end to have less traction in a corner....

    Lift oFF oversteer you will not cure by reducing the traction in the rear, rather you would only make it worse....
     
    Last edited: Nov 2, 2009
  3. Devedander

    Devedander

    Messages:
    4,323
    I would think the only thing that might help is caster adjustement...
     
  4. CaptCalvin

    CaptCalvin

    Messages:
    192
    Just because a spring appears to be compressing less does not mean the weight transferred to the front of the car is reduced. This stuff is basic guys! Its the FIRST TIME in my life I've ever heard of anyone stiffening the front springs relative to the rear to reduce oversteer.
     
    Last edited: Nov 2, 2009
  5. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    He is not, hes talking about stiffening the rear vs the front to reduce lift-off oversteer.

    However

    In the end though the same amount of weight is transferred, the springs help to manipulate the weight in motion.
     
    Last edited: Nov 2, 2009
  6. CaptCalvin

    CaptCalvin

    Messages:
    192
    Best way to figure out whether or not having stiffer front and softer rear springs will reduce oversteer is to test it on a car like the NSX. After some testing, I am keeping my stance on this issue, that having STIFFER REAR and SOFTER FRONT will REDUCE LIFT-OFF OVERSTEER.
     
  7. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    You see Lift off oversteer happens when your in a corner & the weight is shifted forward too fast (from letting off the gas quickly in a corner) That said weight transfer reduces the rear tires surface area on the track. This characteristic is more pronounced in MR cars because of its rearward CG. Throw a hammer sideways. Now you know whats happening in MR cars, the hammer head being the rear end of the car containing the engine, always wants to swing around.

    You want to maintain that there contact patch in the rear that's so important to grip ;) keep your grip as much as possible in the back end where its needed. Stiffer rear springs will only give the front more grip in our corner, the front's grip over the rear being part of the problem.

    I would still look to dampening adjustments for tuning out lift off oversteer. With slightly adjusting stiffness of the front Springs.

    KEEP IN MIND we already dropped our car, SO stiffer springs are required to deal with the new ride height & reduced travel distance (Until fully compressed) We are talking about tuning beyond that ;) .
     
    Last edited: Nov 2, 2009
  8. Lucas

    Lucas

    Messages:
    5,397
    Location:
    Argentina
    Has any of you guys (the ones with a different view than Rotary Junkie's) even tried to see if what he is saying is correct, by turning on GT4 and checking it by yourselves? Because for the sounds of it, you haven't.
     
  9. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    You have got to be kidding me.

    We are not tuning in GT4 so whatever happens in GT4 doesn't matter (Id rather not get into GT4 tuning as Ive taken that way past its limits and quirks, and the dynamics while CLOSE are NOT the exact same) GT4 in any case is as relevant as GT3 or 2 or 1, unless the dynamics are mirrored, but they are not.

    We are also talking about applying real world physics to tuning in the game.

    What your saying is that in order to tune in GT PSP we have to ignore real world physics, & tune like its GT4?

    I disagree. I think the fun about the GT series is that you can apply real world tuning to the cars and get relatively the proper results. I also think the same applies to GT4, but thats a different game ;) .
     
  10. CaptCalvin

    CaptCalvin

    Messages:
    192
    I don't give a fig what anyone says at this point, as there's too much to keep track of. All I care is, in GTPSP with professional physics, When I stiffened the rear suspension of an MR car, there's minimal oversteer at lift off, but when I stiffened the front instead, there is quite a bit of oversteer at lift off.
     
  11. Rotary Junkie

    Rotary Junkie Premium

    Messages:
    9,809
    Location:
    United States
    I love how you didn't directly answer him. Nor did you say you even tried it in GTPSP.


    Also... GTPSP and GT4 have EXACTLY the same physics limitations so I don't whatsoever see your point. The tyre model is different but that's it (more lateral grip loss under excessive longitudinal load and vice versa). Oh and we have more restrictions here. Meh.

    Lastly, the only time you have to "cheat" physics is when the setup you're trying to use would lift a tyre when cornering. Or when going for 300mph or optimum drag times.
     
  12. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Ive done more then my fair share of GT4 tuning, and its still irrelevant.

    NO they are not "EXACTLY the same. While the dynamics are close they are still different, even if not by much.

    The Tire model being of prime importance here as we are talking about manipulation of the tire patch contact, & the W/T on them, the tires being the cars ONLY contact with the road surface, DUH! You cant see the Point, then its beyond you.

    Who's trying to "Cheat" the physics? I'm tuning within them.

    Ive pushed cars in GT4 well past 300mph to just under 400mph with GT4's quirks (Even with more HP and extended gearing cars will not wheelie in GT PSP for example), yawn... Not relevant...

    We are talking about lift-off oversteer.
     
    Last edited: Nov 2, 2009
  13. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    Uhhh no.

    MR cars want to rotate because they have a low Polar Moment of Inertia (read), not because they have a rearward CoG.

    Your hammer example is actually much more apt for a RR layout rather than a MR, a good MR layout will aim for a 40/60 split (front to rear) , which is certainly not hammer like at all.




    Changing spring rates will not change the speed at which load transfer occurs, that's one of the fundamental functions of dampers.

    Allow me to share the words of Skip Barber, from his excellent booking 'Going Faster'.....

    ....also while changes in load will effect the shape and size of the contact patch, that is not the main factor in changing grip levels. That is mainly a factor based on the load itself, along with the grip co-eff between the tyre and road surface (and that itself changes based on load - funny stuff rubber).


    You also need to watch your attitude in a big way, address the point being made, don't have a 'dig' at the person making it, next time you do an infraction heads you way.


    Scaff
     
    Last edited: Nov 2, 2009
  14. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Thank you skip! This illustrates my point, but takes it further giving a more in-depth explanation of how this all effects the tires directly.

    "the shock setting doesn't determine how much load gets to the tyre or how much the suspension moves moves in response to the load."

    "It alters the speed with which the load gets to the contact patch"

    Great stuff...

    THATS why I said you should be tuning the dampers more with slight adjusting of the SR ;)

    Reducing the contact patch is a by product of reducing the load.....
     
    Last edited: Nov 2, 2009
  15. Lucas

    Lucas

    Messages:
    5,397
    Location:
    Argentina
    My mistake. I was given a link to this thread, and I incorrectly asumed it was about GT4.

    Too bad a game is not a 100% accurate simulation of the real world.

    Close. What I tried to say is that you have to stop thinking GTPSP physics = Real world physics, and start tuning with GTPSP physics in mind, to which in order to do so, you should see for yourself if what Rotary Junkie said is indeed true. You will accomplish nothing talking about real world physics all day, and this could have stopped long ago (hours ago) if you have done that, which I know I would have.

    It's very simple: if you are new to tuning in a racing simulator, you guide yourself by the tuning concepts of the real world. But you don't use those concepts alone. That's why I find Scaff's tuning guides for GT4 useful, and it's the same reason why you should forget about the real world for a second.
     
  16. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom

    Then please explain why you said this.........

    ....because that is simply not true at all (as Skip says, that's what dampers do).


    Scaff
     
  17. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Because...

    Speaking about the rear springs.

    Then why does Skip say this...

     
    Last edited: Nov 2, 2009
  18. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    The Skip Barber piece is talking about stiffening Damper rates not spring rates, you quite clearly talked about changing Spring rates.


    Scaff
     
  19. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Spring Rates have NOT been Excluded from having an effect (as they DO), but what he is saying is DAMPERS are what you should be adjusting to manipulate this AS IVE BEEN SAYING, so again THANK YOU, Skip!
     
  20. Lucas

    Lucas

    Messages:
    5,397
    Location:
    Argentina
    Have you followed my advice of checking both Rotary Junkie's and Scaff's suggestion by yourself in GTPSP? :)
     
  21. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    You see Spring rates DO have an impact on W/T in corners impacting how fast and where the weight is transferred to (Front vs Rear), but LIKE I SAID controlling or adjusting this this IS NOT the primary function of the springs & stiffening them too much (taking into account we already made them a bit stiffer after dropping the Ride height to account for the suspensions reduced compression travel) can interfere with the PRIMARY function of the Springs. People should be tuning the Dampers (and sway bars if we had the ability) with slight adjusting to the front SR to tune out lift-off oversteer, as I've been saying.

    The point of mine you have taken out of context was referring to somebody Trying to do tune out the lift-off oversteer by increasing the rears stiffness when he should be tuning the dampers. However I was still attempting to point out the error of the adjustment or at least concept behind it.

    So again, Thank you Skip.
     
    Last edited: Nov 2, 2009
  22. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    Do you own the book in question? Have you read it numerous times from cover to cover? Have you ever taught the basics of vehicle dynamics?

    I can answer yes to all three, can you?

    Skip Barber does not say that spring rates have an effect on load transfer speeds at all, either in that section, or any place at all in the book.

    This is for one very simple reason, spring rates do not effect load transfer speed at all, dampers do. The very name of them should be a rather large clue to that.

    Now please either cite the page number in Going Faster that specifically says that spring rate changes have an effect on load transfer speed or provide your own independent source.


    Scaff
     
  23. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Read this

    http://books.google.ca/books?id=BJU...epage&q=how to effect weight transfer&f=false

    Go to Springs.

    I bet you Still hold that Turbo Book that says Heat spins the Turbo close to your heart, lol!

    (Even though its wrong and its been proven)

    Just Joshing yah, you probably don't even know that book. Or maybe you do, who knows..

    http://autospeed.com/cms/title_Book-Review-High-Performance-Handling-Handbook/A_1804/article.html

    Here is a little pulled out for you...

    Do you really think yours is the only book on tuning? Maybe you should look through it again, especially if your teaching people falsities.

    Springs DO have an effect weather you like it or not. So hit me with your powers because I have PROVEN you wrong.
     
    Last edited by a moderator: Nov 2, 2009
  24. CaptCalvin

    CaptCalvin

    Messages:
    192
    How about none of you let other people tell you how you should feel when you change certain tuning options and instead try it yourself? I tried it and I got my answer.
     
  25. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    Not a single word of that covers the speed at which transfer occurs!

    I've not disputed that spring determine how load is distributed, or that they determine exactly how much movement occurs under transfer, or that the can be used to control under and oversteer. Those are the only areas that your quote covers, it does not discuss the speed of load transfer at all.

    You've not proven anything beyond the fact that you have an attitude that is not going to see you last long here at all, you've been warned enough times now and the next time you make a personal dig at anyone you get an infraction.


    Scaff
     
  26. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    Agreed that this is a game and the real world way of thinking doesn't always apply.

    Anybody can really try whatever they want. I personally try to tune the cars as best I can based on the real world, that's whats fun to me. Everybody's different.

    If car A has stiffened the front springs leaving the rear untouched Vs Car B with the Rear stiffened & the front untouched, Hypothetically in the same corner Car A will be getting More weight in the front vs the rear, and would reach the amount of weight in the front that car B would max out at then surpass that until reaching it's own max (that is a higher amount then car B) in the same time period. Therefore weight is transferring to the front at a higher rate, simply because MORE weight is transferring in the same period of time... Not more total weight, but more of the divided weight.

    ^
    Do your worst... yawn.
     
    Last edited: Nov 2, 2009
  27. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    You do realize that the last part of this is totally contradictory!

    Changing spring rates will determine how load is distributed between two tyres on an axle line, it will not in any way change the total load being transferred from the rear to the front of the car. That is what you appear to be saying and you then change your mind, none of which has anything to do with the speed at which the load is transferred.



    Feel free to keep this up, it doesn't bother me a bit and will only last so long until one of two actions occurs. You start to behave like a member here is expected to or you get banned, either outcome is good for me.

    If you want to fast track the latter option, just say the word.


    Scaff
     
  28. SiNiST3R

    SiNiST3R (Banned)

    Messages:
    542
    It's not, you just misunderstood.

    Tires on the same side, the SAME total weight distributed between the 2 tires on the out side of the corner.

    Wait! I did make it clear...

    That's what Ive been saying. I said it doesn't change the TOTAL load, JUST how its distributed (more front or more rear on the outside wheels in a corner) I have NEVER said otherwise, Ive always maintained the total weight being distributed remains the same. But weather 80% front 20% rear (100% being the total weight transferred to the side) or 70% front and 30% rear, get it?


    Already Did! Why do you keep threatening me?
     
  29. Devedander

    Devedander

    Messages:
    4,323
    Correct me if I am wrong here... but if you have stiffer springs up front, doesn't that mean the front of the car will compress less under braking or cornering, thus leaving it relatively higher to the rest of the car, thus meaning relatively less weight is being applied to the front of the car?

    I am not sure what you guys mean by speed of weight transfer as the speed of weight transfer through a solid object I would imagine is the same as the speed of a force being carried through that object which is for all intents and purposes instantanious (I suppose some time is taken due to comrpession of the particles in the frame of the car). So I am not sure how speed of transfer of energy can be reduced at all...

    However it seems if above is correct where stiffer sprigns keep the front of the car relatively higher through a corner or braking, then the time it takes under the same conditions to realize the results of of the weight being transfered is indeed longer as you need to brake/corner longer/harder to compress the front to the same height as softer sprigns.
     
  30. Scaff

    Scaff Staff Emeritus

    Messages:
    24,627
    Location:
    United Kingdom
    Body roll (what you see) is simply a visual sign of load transfer having occurred, how much body roll you see does not change the amount of load transferred at all.

    You could replace all the springs in a car with solid metal bars, all other things being equal you would still get the same amount of load transfer occurring.


    Speed of transfer is how quickly load is applied to the contact patch of the tyre and while it does seem to be instantaneous, that is not the case.

    I will use Skip Barber once again to explain this....

    So the more quickly the suspension system can react to the load being transferred, the more time it has to spread that transfer out over and the more gradual the load is applied/removed. Now you are talking differences in fractions of seconds, but these make a huge difference when talking about vehicle dynamics.

    Keep in mind that while the body of the car is (more or less) rigid, suspension is not, and this has a big effect on how load is distributed (springs) and how much the car moves (springs) and how quickly it does so (dampers).


    Regards

    Scaff

    No you did not make that clear at all, in fact very little of what you post is clear.




    I get what you are saying, but you are wrong.

    Changing spring rates (if that is the only factor being changed) will not increase the amount of load transferred from the rear to the front of the car, a change in spring rates will change how the load is distributed between the two tyres at the front.



    Just to make this clear are you saying you wish to be banned?

    I will warn you that should you reply yes to this question, then my next action will be to do just that.


    Scaff
     
    Last edited: Nov 2, 2009