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Old 25.3.2015   #1160
JackCY
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Join Date: 26.4.2007
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Car engineer:



Ono to prave az tak jednoduse nejde, ala zvednu uberu X o 2 stupne a je "vyhrano". Ale predni pruzinu na minimum coz na E30 by melo byt 3.9Hz, i to je dost vysoke ale jezdi to s tim ok. Merc ma u me nastaveno 3.2/3.1Hz, a neco podobneho s malym rozdilem funguje i na E30, no ono vesmes na vsechny auta nebot velke rozdily zpusobuji problemy. At uz je to na jednu nebo druhou stranu.

Vetsinou do 0.5Hz rozdilu je to OK. Ale ten defaultni rozdil na E30 je snad pres 1Hz a to je velky rozdil.

Quote:
Stiffness

Q) What does it do? A) This is simply how stiff the spring is – a stiffer spring compresses less under load compared to a softer spring, and vice versa.
Q) How do I tune it? A) Part 1: Suspension frequencies
Stiffness is relative to the weight of the vehicle, so rather than tuning by stiffness you should be tuning spring frequency. Yes, that catches most people out, so don’t worry. A higher spring stiffness gives a higher frequency, and vice versa. While lower frequencies allow the tyre to stay in contact with the road as much as possible (and hence maximum grip), they also allow more body roll (which reduces maximum grip due to tyres being load sensitive). High frequencies do the exact opposite.
So obviously there is an optimum point in spring frequency – in real life this is known to be around 1.9-2.2Hz for cars around 1 tonne in mass (typical for GT racing cars). That doesn’t automatically mean these frequencies are best for LFS, however. As the weight increases this optimum frequency decreases and vice versa. Since the heaviest car in the game clocks the scales at just over 1.2 tonnes, 2Hz should still be a good point to start from and I wouldn’t recommend dipping much lower. For lighter cars, this optimum point may reach as high as 3Hz, although I wouldn’t recommend going quite that high for any road car in LFS. It’s best to experiment as see what feels best for you. Formula 1 cars are known to use anything in the range of 4 to 8Hz, but there are more reasons for that which I will explain in part 3.

...

Another effect of changing the spring frequency is how it affects the handling. Higher frequencies make the car more responsive to steering input although setting them too high will make the car nervous. Lower frequencies, although making the car less responsive, helps make the car more chuckable (i.e. you can throw it into corners and it won’t mind so much) but going to low will make the car wallow and you won’t be in complete control. So clearly there is a range or useful frequencies to use, and somewhere in the middle of it all there is a sweet spot – though where it is also depends on the driver.

Part 2: Car balance
The second thing you can do with suspension is alter the balance of the car – which comes in very handy. While at first it may seem that equal frequencies will give neutral handling, this is only the case if the track widths are equal. If the front track width is wider than the rear (as is usually the case), neutrality is found with a slightly higher spring frequency at the rear. Since all real race cars are RWD, it is normally acceptable to use a rear frequency 0.15 to 0.25Hz lower than on the front as this will introduce some basic understeer. It is best to use as little as possible though because due to the nature of slip angles on tyres, a slight amount of oversteer is fastest. The better your throttle control and counter steering abilities, the less understeer / more oversteer you can get away with. For FWD cars you’d want the rear harder than the front by around this amount (or the front softer than the rear – depending how you look at it). If you were trying to make the car more neutral then reduce the difference in frequencies (this isn’t the only setting that affects car balance however (in fact most settings do really), though one of the two main ways, the other being antiroll).
I wouldn’t recommend making the difference in frequencies greater than 0.4 or 0.5Hz though – if the car still isn’t handling like you want then either some other settings need changing or maybe your style of driving (but that’s not the purpose of this guide).

Part 3: The downforce twist
Unfortunately just when you think something seems relatively simple, something else comes and complicates matters. In this case that thing is downforce. With downforce, as your speed increases you are getting air to push the car onto the ground, which is great for grip as you get more force sticking the tyre to the ground without the nasty side-effect of having to haul more weight around. Of course as speed increases there is more force being exerted onto the springs, so the ride height will be reduced (and most likely, it won’t be reduced equally front and rear, so the car pitch changes also). And of course changing ride height alters the camber of the wheels, making it harder to get camber perfect for both high and low speed corners.
Note that downforce does not actually affect spring frequencies (contrary to what older versions of the guide stated – these were incorrect), and thus does not affect damping either.
This brings me back to the Formula 1 car comment and why they use such high spring frequencies. The first reason is of course they run with huge amounts of downforce, to such an affect that most of the force holding the car to the road is from downforce rather than the weight of the car. Though this does mean the car could drive upside down (say, on the underside of a bridge) which could make for some wacky racing. Getting back to the point, why do cars with downforce need to run stiffer suspension? This is due to the issues I previously mentioned, e.g. changing of ride height, pitch (which in turn affects downforce) and camber. Stiffer suspension means these properties change less as the car goes around the circuit, making it easier to setup. Also downforce is only created when air is travelling over the car in the correct direction. So high slip angles would mean a loss of downforce and for this reason tyres with low optimum slip angles are used. This also means that the cars are going to snap when traction is lost, so higher spring frequencies are used since their benefits (increased car control) are present but their downsides (worse handling over the limit) no longer really matter.
Another reason F1 cars use such high frequencies (and very little suspension travel) is that, unlike GT racing for instance, they use soft tyres with fairly tall side walls. It is the give in the side walls that softens the impacts and cushions the driver and allows him to still see clearly (having the suspension frequency too high would otherwise impair the vision of the driver over non-flat surfaces).
Muze se zdat ze cast 3 je zbytecna ale opravdu neni.
Pritlak od kridel neni nic jineho nez extra vaha, tezsi auto se stejnymi pruzinami tak bude mit nizsi frekvence. Stejne jako kdyz auto nalozis necim, bude tezsi a bude mene skakat. Treba jako sports lorry v Top Gearu.
Kridla jsem nakonec snizoval, coz pro me znamena ze auto je zivejsi a jede rychleji na rovinkach, lepe zataci ale take vice driftuje a to zejmena pokud za to vezmu moc ve vysokych rychlostech. Take to vice skace nebot mam mene vahy na zadni naprave. Vzdy je to nejaky kompromis.
Slip angle si chce take ohlidat, vice mene se nastavuje pres TOE a differencial. Je to defakto takove klouzani. Cim vyssi toe tim vice to klouze, je to lehci na ovladani, ale ztraci se cas nebot kola jsou vice sikmo. Ano je to 0.1 stupne rozdil treba, ale je to znat hodne na ovladani a nekdy i na case. Mensi zadni toe vice "kouse" = utrhava se zadni naprava vice nahle.
Ja jezdim 3/1 kridla, dagger jezdi 2/2, ja mam toe 10/10 a vice, on mene, na rovince jsem nestihal ale asi jsem mel poskozene auto, i tak obcas jezdime na dvere po boku, coz je na Nordu docela zabava s tim jak malo je tam mista. TOE to chce co nejmensi co clovek zvladne, at uz je to vpredu ale hlavne vzadu.

Samozrejme odladit to cele aby bylo minimalni toe a kridla, dobre to zatacelo ve vestine zatacek ale zaroven to nebyla rakev na kolech, zabere hodne casu a jezdeni.

AC je na TOE docela citlive, alespon oproti LFS. Nizsi kridla vyhodu maji, zejmena zadni a ten rozdil na rovince je vyuzitelny, je to defakto cas zadarmo.


Nordschleife trva nastavit, jedno kolo cca 7min Tourist nejkratsi. S kazdym kolem zkusim nejakou zmenu a jak se to chova. Vyhoda je ze staci jedno kolo a nemusim jezdit 3 jako na jinych tratich ktere jsou kratsi. Casove to az takovy rozdil neni v testovani.

Az doladim ppfiltry tak asi natocim video te 6:56 jizdy, pokud nezajedu neco rychlejsiho do te doby. Replay mam ulozeny, bezchybna jizda to tedy neni ale je to 100% grip a vcelku cista trat od ostatnich aut ze nikoho nepredjizdim a nikdo me neblokuje.
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Last edited by JackCY; 25.3.2015 at 00:47.
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