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Thread: More suspension types supported

  1. #1
    lordpantsington's Avatar

     rFactor 2 Validated PC Specification 

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    Oct 2010
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    Grand Rapids, MI

    More suspension types supported

    MacPherson being at the top of my list.

    Actually would like to see the level of depth that was added to the tires added to suspensions.
    Add coilover instead of pushrods, digressive valving, the ability to have non linear change in damping per click, size of bumpstop, multiple springs per damper (tender/helper)...

  2. #2
    lordpantsington's Avatar

     rFactor 2 Validated PC Specification 

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    Grand Rapids, MI
    Small bump to add that missing completely from the garage settings are damper canister pressures. A simple multiplier (like brake pressure) could be used to simulate this.

    More info about multiple spring systems:
    Until the Tender/helper binds, the spring rate for a multi-spring coilover is: (Main Rate x Tender) / (Main Rate + Tender Rate). After it binds the rate is simply the rate of the main spring. It appears that a multi-spring system provides more rebound travel, and softens the ride when using higher main spring rates.

    At the very least 3 additional parameters per corner would be needed in the HDV to use a secondary spring, Something like:

    Spring2Travel=-0.036 //defines the wheel location where the spring rate is using only the main.
    Spring2Range=(43000, 1000, 1)
    Spring2Setting=0

    It appears that rf & rf2 initializes a car with no load on the tires, (suspension position 0), and then drops the body to determine load which also defines the static suspension position (Load/spring rate-taking geometry into account). The distance from full extension to where the bump rubber is contacted is determined by the travel entries in the HDV. The upper limit of suspension position is limited by the rising rate of the bump rubber.

    I see no reason why another step cannot be implemented. It seems to be how bump rubbers are already being used. Instead of the car starting out on main springs then transitioning to combined main/bump rubber rates, it starts on combined main/secondary spring, transition to main only, then transition to combined main/bump rubber.

    That was the simple addition. Something more in-depth considers total damper travel, bump rubber lengths/compressibility, free and block lengths of the springs. Probably means more behind the scenes coding, but at least we could implement actual bump rubber rates, and real life spring data. I would love to see available travel to bind change due to spring rate change, and be able to compensate by changing the free length or adjusting the size/stiffness of bump rubber.

  3. #3
    Mitt Wilson's Avatar

     rFactor 2 Validated PC Specification Facebook profile Where I race rF2 Rank Laptimes 

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    Beyond AWESOME! rf Motto is Alive and Well!

  4. #4
    jtbo's Avatar

     rFactor 2 Validated PC Specification Modding Group: Finns on track 

    Registered
    Jan 2012
    Quote Originally Posted by lordpantsington View Post
    Small bump to add that missing completely from the garage settings are damper canister pressures. A simple multiplier (like brake pressure) could be used to simulate this.

    More info about multiple spring systems:
    Until the Tender/helper binds, the spring rate for a multi-spring coilover is: (Main Rate x Tender) / (Main Rate + Tender Rate). After it binds the rate is simply the rate of the main spring. It appears that a multi-spring system provides more rebound travel, and softens the ride when using higher main spring rates.

    At the very least 3 additional parameters per corner would be needed in the HDV to use a secondary spring, Something like:

    Spring2Travel=-0.036 //defines the wheel location where the spring rate is using only the main.
    Spring2Range=(43000, 1000, 1)
    Spring2Setting=0

    It appears that rf & rf2 initializes a car with no load on the tires, (suspension position 0), and then drops the body to determine load which also defines the static suspension position (Load/spring rate-taking geometry into account). The distance from full extension to where the bump rubber is contacted is determined by the travel entries in the HDV. The upper limit of suspension position is limited by the rising rate of the bump rubber.

    I see no reason why another step cannot be implemented. It seems to be how bump rubbers are already being used. Instead of the car starting out on main springs then transitioning to combined main/bump rubber rates, it starts on combined main/secondary spring, transition to main only, then transition to combined main/bump rubber.

    That was the simple addition. Something more in-depth considers total damper travel, bump rubber lengths/compressibility, free and block lengths of the springs. Probably means more behind the scenes coding, but at least we could implement actual bump rubber rates, and real life spring data. I would love to see available travel to bind change due to spring rate change, and be able to compensate by changing the free length or adjusting the size/stiffness of bump rubber.
    Travel upwards is until bump stop is reached, AFAIK, but I'm not 100% certain of these, settings are so far out from real world that it is sometimes difficult to get head around of them.

    Anyway, what you set for wheel movement range is more of a suggestion, spring stiffness limits movement range from both ends. 0.2 gets you different movement range with different spring rates, but that movement is without hitting bumpstops, mostly one can adjust percentage of upwards and downwards movement with those settings, so that you can get more movement upwards or move movement downwards, but not actual movement range, imo.

    I'm inputting real spring rates and try to meet real wheel movement, but so far I have not found much better than guestimating point when bumpstop is met, I can see travel from motec, but I can't see point when bumpstop is met, I can only try to shake car and try to estimate it visually, then try to look from motec and see if there is change in damper velocity like if bumpstop has been hit, but I really think there has to be better way.

    If I know how much wheel can move in real car and point where bumpstop is met, then I would like to enter those values to engine or know the formula that solves proper settings, adjusting by trial and error is bit .... inefficient.

    There is quite a lot however that I have had to guess, read what others have guessed and so on as there has not been much insight from how things work or how they are intended to be used, so I guess that more examples of real world values converted to rF engine values kind of documentation might improve this aspect greatly.


    4-link suspension is top of my list however, mcPherson is something you can emulate, Car Factory tool is still usable for that to get numbers that engine transforms to proper movement, but currently there is no way to make 4-link/drag-link. However this has been already commented by ISI that it will probably come when there is time for new features in that area, I guess at same time window other types are taken into consideration too as it would make sense to work all things related to suspension at once instead of doing little here and there.

    All due their time though, but it is good to bring things up for discussion and maybe get different angles to subject.
    I am not a slave of my emotions, I can still be nice at times
    Learning suspensions, good read | my modding information website

  5. #5
    lordpantsington's Avatar

     rFactor 2 Validated PC Specification 

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    Oct 2010
    Location
    Grand Rapids, MI
    Correct, and when bumpstop is met the spring rate is the combination of the spring rate and rate of the bump rubber (which is nonlinear). The theory I'm operating with is the reason the bumpstop rates are so astronomical is because they are the deciding factor in when the travel runs out. It might be more accurate to state as "when damper velocity is slowed to zero" because there seems to be no actual point at which travel runs out and the remaining load transferred directly to the chassis. I believe the correct approach would be to figure the spring rate of a solid object (like bar steel) and set that at the end of your travel, then work backwards to get the rates of the stops as required by rf from where the contact point is. BUT I have not tested that.

    I know exactly where bumpstops should be met from working up a blueprint of the coilover itself. From that I've determined total travel and available travel until stop. From load/spring rate I get rebound travel, the remaining is travel to bump stop. I've gone so far as to drop the car off a cliff to see if I could see some sort of hard stop, AFAIK they don't exist. I was looking into your damage page yesterday to see if I could set a maximum load for the suspension causing it to break. Certainly that would create a hard stop LOLZ.

    Anyway the secondary spring is needed because with the high spring rates I am running leave little rebound travel, and far too much bump travel. They are almost exactly swapped from what they should be (current rebound travel should be bump travel), and it takes the bumpstop completely out of play. The only way I can get the rebound travel I should have is to soften the spring. Then my damper rates are not paired correctly with the spring rates.

    Emulation? Correct, but the want is for direct implementation. My bump wasn't to push a "When?" type question, it was to gain the subject a bit of viewing and add some info to maybe help them along.

    Having to convert Tin-top coil overs and struts to pushrod open wheel type suspension is tiring without proper kinematic graphs to correctly emulate. I know locations, I don't know how the intricacies of the suspension system affect roll center; dynamic toe, camber and caster.

  6. #6
    jtbo's Avatar

     rFactor 2 Validated PC Specification Modding Group: Finns on track 

    Registered
    Jan 2012
    I know also perfectly motion ranges for my real car, but in rfactor, well, I can see movement with motec logs, when I use motec plugin, but then there is indeed that unknown component, where in rfactor motion stops and when bump stop starts to effect.

    Most of the time range in driving seems fine, but when I manage to barrel roll a car or drive off the cliff I can get tires poking trough car's body, which is also exact problem you describe.

    Now it would be really sweet to need just get points from car and put those to rfactor and it would result similar functioning suspension, but I don't know if that is very realistic dream, don't know if that is direction ISI aims with their improvements.

    I have used in rF1 that suspension gets destroyed method, I think it is good method to keep racing more real like, one should care the car, so in any case such would be thing to do, just set it not a bit random, at least in rF1 force 10 times larger is not enough to break it if there is random component, maybe that sees improvement also, who knows
    I am not a slave of my emotions, I can still be nice at times
    Learning suspensions, good read | my modding information website

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