What does a differential actually do?
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- Опубликовано: 10 сен 2024
- The differential is one of the most important parts in race cars that affects your lap times more than anything else. Understanding and controlling it while driving is key to lap times - not just in Assetto Corsa Competizione!
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Simracing is difficult. Learning how to drive fast takes time, dedication and persistence. Assetto Corsa Competizione is one of the best simulations with highly sensitive aerodynamics that want to be respected. Telemetry, such as motec helps with analyzing car behavior and finding major issues in the car setup or driving style. Special sim racing hardware also helps with becoming better, but certainly is not the solution to your problems. Load cell pedals offer better feel. Stronger but most importantly more detailed force feedback of e.g. direct drive wheels offer more immersive sensations. Though I know and I've seen throughout the years, people with entry level hardware perform on top level.
Knowing the Reason, why you have to go for 70-80% Gas Input to not understeer in corners is a blessing. You can really play around with the diff if you know how you want to drive and want to finetune it. Thank you Nils!
As a competitive drifter who started competing last November, I learned a lot about driving and setting my car up. One of the big learnings I took was how to set up the differential correctly. When I started competing I simply set my diff to lock 100% on accel and decel (We are using LSDs just like GT3 cars), but later on I learned that it actually makes a huge difference to open the diff up on decel. I haven't experienced any situations where it was super beneficial to open the diff up on accel as I really like the amount of rotation it gives, but there are lots of different styles in drifting. Opening up the diff on decel really helped me to stop overrotating the rear of the car in certain situtations and it completely changed my chase game too. Finding the right preload is not as necessary but it does make a slight difference in how the car feels and when the diff starts letting slip happen. With slight throttle adjustments I usually want my rear to stay locked to gain more rotation and when I let off throttle a bit longer I want my diff to let the rear wheels do their own things to a certain extend. I'm still by far not a setup master but I'm learning more and more with time.
So I've been trying out these tunes from coach dave as someone getting into sim racing, and I knew the problem was that I wasn't driving the car hard enough. The problem was that I couldn't figure out why. What about driving the car harder would fix it, it's not just brute force lol, and this video is the answer. I need to practice engaging the diff. huh. Great video
gotta practice feeling the diff impact. everyone engages it, just not deliberately
@@SimracingPopometer Can you give us clues on how to feel the diff impact? I have no racing experience and just don't get it.
What an explanation, thank you so much for sharing this knowledge!
Derzeit bester Sim-Channel auf RUclips meiner Meinung nach - unterhaltsam genug, ohne auf ein Iota Informationsgehalt zu verzichten. Selbst Videos wie dieses hier, wo ich als primärer AMS2-User (notgedrungen, das Differential war ja da immer mal wieder problematisch ;) ) gewisse Vorkenntnisse habe, schaue ich wirklich gerne an, und es ist auch immer wieder spannend, das eigene Wissen noch ein bisschen zu erweitern bzw. zu ergänzen. Auch, wenn ich mit ACC im Speziellen eher wenig am Hut habe; ich komme sowohl mit dem für mich unberechenbaren Ansprechverhalten am Gas als auch mit der seltsam leblosen Bremse nicht zurecht ^^
Ich hoffe, wenn 1.6 für AMS2 erscheint, wieder das inzwischen gewohnte Review zu sehen - bin wirklich gespannt, was du zu dem Update zu sagen hast. Vielleicht sieht man sich ja dann sogar mal online in einem LFM-Rennen...
Ich habe ja Beta Zugang - und bin bei den LFM Tests manchmal dabei. Ich würde mir immernoch etwas schärferen Grip wünschen, aber in Summe kommt es jetzt schon richtig gut rüber. Insbesondere langsamere Autos sind ne Bank in AMS2 (Lotus Super 7 bzw. Caterham z.B.).
Das Problem von AMS2 wird eher woanders liegen: Zu viel Content, zu viel Tiefe in den Setups der Prototypen (was natürlich den Prototypen selbst geschuldet ist), was es für viele einfach schwierig macht zu wechseln, weil man von vorne Zeit investieren muss, die man nicht hat.
@@SimracingPopometer
Kann dir da aufjeden Fall zustimmen - man hat zeitweilig immer noch das Gefühl, als wäre man in Wahrheit ein kleines bisschen über dem Limit, aber die (GT3-)Karre driftet vorbildlich um die Kurve. Ist aber so weit reduziert, dass es mich (derzeit) nicht sehr stört; insofern ist da mE wirklich schon viel gewonnen, denn im derzeitigen Release ist es ja teilweise schon an der Grenze zum Lächerlichen, was das Heck so alles anstellt und mitmacht.
Lustigerweise sind meine Favoriten (auch in der Beta) meistens die high-downforce Fahrzeuge, also insbesondere die Formelkisten (derzeit insbesondere V10G1, 2 und Reiza). Weiß aber nicht, ob die für dich überhaupt ein Faktor sind.
Wenn LFM kommt, wird es irgendeine Form von Fokus brauchen - mehr als zwei oder drei Klassen würde ich zu Anfang auf keinen Fall anbieten, und das kontinuierlich. Lieber mehr Nachfrage als Angebot als zu viel Angebot, bei dem wegen der Zersplitterung gar keiner mehr zugreift.
Den Setup-Untiefen, die es zweifelsohne gibt - gerade von der Aufhängung und dem Differential kann man sehr leicht überfordert werden, selbst mir geht das häufig so - könnte man mit "fixed setup" Serien begegnen; das Spiel bietet die Option ja. Ich weiß aber nicht, inwieweit so etwas bei LFM grundsätzlich überhaupt denkbar ist - iRacing hat ja recht viel Erfolg damit.
Ich gebe dir aber recht, dass "offene" Setups bei der derzeitigen eSport-Jungfräulichkeit des Spiels eigentlich nur voll danebengehen können; dann fahren zwei Leute um den Sieg und der Rest fragt sich, wo (und warum) er die 20 Stunden hernehmen soll, um am Ende an derselben Stelle rauszukommen.
Moin. Also ich fahre Deine Popo Setups für den Porsche permanent. Die Differentialsperre passt hier in der Regel und die Rotation ist meistens im grünen Bereich. Aber super Info.
As a Porsche driver, that helps a lot. Now knowing the theoretic part better it is still the problem that I can’t do 80% 😅 it’s always pedal to the metal. I guess the VRS pedals are also part of my problem. Having a really really soft spring and no changing of resistance during the whole way of travel 🙈
pedals are fine, the issue is your heavy foot :))
As a real racing driver for 30 years, i have not found that a locked diff will cause entry understeer. Quite the opposite. I have raced shifter karts, solid rear axle, and a Lexus SC400 with a welded diff for years and neither of them had any entry understeer. It helped rotate the car in entry and was amazing on exit. No loss of grip there. I have also found that an open diff is the opposite as the rear is much harder to start rotation on entry, and exit is abysmal if there is any camber in the track at that point.
yeah, its not as straight forward.
its car and grip dependent.
the weight bias has impact as well and you'll not get a lot of rotation with the open diff when its heavily front biased - but huge impact if rear biased. and depending if the car is generally rear of front limited in terms of grip the locked diff will give you over or understeer. its a little more complex in the end. but its about getting the principles across here.
I’ve started racing my BMW E12 M535i Goup 2 eleven years ago. Although it is a classic car, it behaves pretty much as Nils states. So I guess it really depends on a lot of other factors, mainly weight transfer.
BTW, you nailed it with the thing about the power delivery of racing cars. I balance mine on turn exit with around 20 to 30% throttle. It gives me the perfect subtle controlable slide.
Good explanation which confirmed my idea if how a diff works on a race car works. The summary at the end is also great. The title of the video is just such a RUclips thing... lol
yeah I'm sorry. but we need the clicks :D
:'D
Please make a video on how to drive with TC 0. It seems to be about throttle control and somehow controlling the inside and outside rear tire slip, but no one tells us how we do that. Maybe you can show us how your popometer software can train us to success!
I'm literally at least 2 seconds slower with TC0 because I might snap oversteer at any moment and I am way too conservative exiting turns. But I must admit it's at least twice as fun! But my ultra conservative throttling might be confounding me, according to your incredible LSD video.
maybe that helps further :) ruclips.net/video/kJjDmGSjJOg/видео.html
Apart from that a lot of the "secret" why it works is, and the popometer comparison to pro laps would show you:
- car placement makes up 33% to be able to put the power down
- 33% 'state' of the car, i.e. which tire and axle is operating how much above the limit just before you put the power down
- 33% practice
TC0 becomes easy once you drive the rest of the corner correctly and the car isn't challenged as much on the exit. If you want to drive without TC on corner exit, you must make it easy for the car to put the power into the ground. If you still have too much corner to do, then it won't work.
What about the relation of preload with regards to the differential behaviour?
basically no impact. it will help slightly with limiting entry rotation if you crank it up, but that will make it more snappy on exit. and vice versa. but its a VERY LIMITED EFFECT in the first place. we'd need the clutch plates or ramp angles to have better control over the diff, but GT3s generally do not have that available to adjust
Hallo Nils, vielen Dank für die Erklärung. Kommt gerade zur rechten Zeit, da ich mit dem AMG öfter mal in der 130R (Suzuka) abfliege, wenn ich das Gas zu stark lupfe..
The livery on the car is 🔥
As always, very good video Nils !
thanks mate!
I remember you saying a while ago the diff settings only kinda work in ACC on the Bentley. Is it still true? I'm too much of a bad driver to know if it is or is it just placebo I'm feeling.
the preload setting in general has very little impact, the other settings like clutch plates or ramp angles have bigger impact, but aren't available to adjust here (or in GT3 in general). the bentley is one of the few cars though that keeps rotating on power without slipping the outside wheel. not necessarily diff related, but i think its just locking a little later (these things might change from patch to patch and havent touched it quite a while)
@@SimracingPopometer oh ok, thanks nils!
@@SimracingPopometer Is this V1.9? I remember V1.8 Bently just wanted to snap oversteer suicidally, but in V1.9, Bently was sooo guud, but the BoP made Bently slow shit. Bently felt so guud when V1.9 came out... 😥
I think that a high preload stiffens the car when turning in during braking and coasting and causes more understeer. Is this true? There is a point at about 80 Nm when the ffb feels "freer" and "springy" and not like "sand", and the car seems to more freely turn in. (on a CSL DD 8 Nm.) I have never used telemetry to analyze this "feeling". It "feels" like 80 is the max point when the stiff sandy feeling is alleviated. Is this why the meta is to set it to minimum 20? If I compare 20 Nm with 120 Nm, I can definitely "feel" a difference in FFB when braking and turning in. The 120 feels like dragging a stick through sand when turning in while anywhere from 20 to 80 Nm feels springy, and I swear the car turns in more easily with less understeer. If the "feeling" doesn't matter and you can determine that there is absolutely no difference in understeer no matter what the preload is from min to max settings during braking and coasting, it would be of great help. (I'll just set it to what "feeling" makes me happiest. lol)
None of this makes sense, since a higher preload means the rear wheels can independently spin at different rates longer until higher torque locks the wheels. Which means the "sandy" feeling means the LSD is free? (I really don't like that "sandy" feeling. But feel free to tell me that "sandy" is actually better for performance. I'll be most unhappy, but thankful for the info.) Or does alleviating the sandy feeling mean the balance of wheelspin differences are optimized? Or oppositely that we want the sandy feeling? As a non-professional, I do everything for enjoyment-err I mean performance! No! feeling good and having a clean FFB is so much more enjoyable than a sandy FFB. You can tell me I'm nuts!
I get the feeling you are correlating things that shouldnt be correlated.
"sandy feeling" is not a side effect of any differential setting. That feeling only occurs if you completely overdrive the front axle and scrub the tires massively. You should never get to this point as it destroys the tire. It might occur earlier with different differential settings in theory, but the preload impact on the car is absolutely minimal and shouldnt be reflected in the FFB. So I think there's a bigger general flaw in your driving approach - even if it might interact with the differential.
Thanks Nils for making these for us. Are waiting ac evo for a lot?
i am not aware when AC Evo sees the light of day, but the issue in the video isnt a game issue, its just how things work!
That's a pretty good video.
I've found the type of pedals you have makes a big difference. Some of the pedals like the lower end ones jump up to 50-70% pretty quickly
The other question I have is how does the TC affect the tire slip? Some tracks I'll use 1 while on others I find using 2 or 3
Then how much does the damping make a difference?
A perfect example would be turn 4 or 5 at Brands Hatch. The left back up the hill before the str8. That turn kills my lap times when I get it wrong. It's the only track I can't get down to a competitive time I'm stuck at 1:23.
There's a lot of ungelation in a few of those corners and I often experience the inside tire slipping. I just cant seem to get my set up right for that track
TC depends on the car. Some cars will have the tire in desirable slip range with TC on, some cars will cut before there tire is where you want it. Some will allow enough slip, but then cut fiercely when you go slightly too far. Some apply the TC already when the inside wheel slips before the outside wheel is affected - which is much too early.
Damping: hard to judge, its such a subtle thing. I'd think in terms of damping rather with general traction in mind rather than controlling a certain slip. the more sharp your front end is, the more difficult to balance the slide, so you can "weaken" your front end to have a more controllable rear in general.
Brands hatch: Yeah, just a shi**y bumpy exit there. When you already struggle for traction its hard to get this one right, and whatever you do in the setup there will hurt in the fast turns. The bumps will trigger the TC if its on, and cause the rear to snap when off, or even have you run into the RPM limiter on some cars (M4)... Just not a nice place, like all british tracks ;)
So... how do we adjust this in ACC?
preload, but that doesn't do much, so: you don't except with your foot
The times might not matter, but I'd lower LSD preload to max 80 just because the turns feel more "springy" and less like dragging a stick through sand. This vid seems to imply that braking and coasting turn in isn't affected at all, but the FFB "feeling" changes a LOT. I set it to where I feel happiest, but that could mean I set it to the worst. I don't have access to the popometer telemetry. I'm inching closer to emptying my bank account to sub to his popometer, but I need to know he will train me to race with TC 0. But DOH! ACC is ded and AC Evo is soon to stomp out AC and ACC! I'll look forward to what this popometer can do with AC Evo. Ima gonna be 100% into AC Evo! Until then, Ima be in Forza Motorsports, because that's my skill level. 🥲
@virtualawakening2299 you can use the tool without subbing, just wont have the additional data channels ;)
and I answered to your other comment. the preload should not affect ffb!
also the cars all have different ramp angles, you can't take a preload value from one car and assume it does the same on another. precision is important here.
I'm not sure how far off the fast lap times you are, but you only have to worry about TC 0 when you are missing the last 1-3 tenths.
ACC is gonna stay with us for a while. AC Evo will unlikely be a replacing game, looking at the content they shared so far - road cars.
Hi Nils thanks for the video. Can you please say a few words about how the changes we can make in the setup affects the differential? Does it affect how much power is needed to actually lock it or is it the force that "binds" the rear wheels together? How should you adjust it in case of under-/oversteer on entry/exit.
the preload is largely ineffective. so you cannot adjust the differential behavior.
you can get a tiny bit of more locking under coasting to get some stability from higher preload, but the effects are very limited.
on throttle lowest preload would help to prevent the binding a tiny bit longer, but the torque from the engine is so large usually that the preload is too small in comparison no matter the value
@@SimracingPopometer Thanks.
Hi Nils, Very nice video about the differential. So we are talking with TC OFF right ?
yes, indeed. but during coasting of course TC does not matter and with TC you are also more aggressive on throttle and will always lock the diff - the TC then cuts heavily to prevent the outside wheel some slipping. currently though it can happen that the TC will already engage with the inside wheel slipping, taking power away BEFORE the car starts sliding
Do you think with ford TC 4-6 you can use this slip/rotation on corner exit? or is it only tc 0
ford can surely do that with low TC levels, but 4-6 might be too high
Moin moin Nils passt ja irgendwie zu dem Video ohne TC fahren von vor paar monaten ich fragte dich darauf vor paar tagen was dazu. Zu diesem video wenn das differential praktisch über das Gaspedal gesteuert wird wenn ich es richtig verstanden habe. Wozu ist dann die einstellung Differential bei Mechanischer Grip. Ich liebe den 992 GT3.
Lieben Gruß Micha
das preload sorgt dafür, dass das differential weniger zusätzliche kraft braucht um gesperrt zu bleiben. also aufm gas sperrt es noch schneller (merkt man aber nicht, weil es ohnehin sofort sperrt), und beim coasting/bremsen, drück das preload die kupplungen auch nochmal mehr zusammen, so dass das differential etwas stärker gesperrt bleibt. das preload ist aber eine sehr wirkungslose einstellung insgesamt. man müsste auch die anzahl der kupplungsscheiben justieren können, oder direkt an die sog. "ramp angles" ran, um eine echte verhaltensänderung zu erwirken. letzteres geht bei GT3s aber nicht.
3:50 why would an open diff make a car overly sensitive to oversteer on corner entry? I thought an open diff provided maximum grip on entry.
no, because both rear tires can then rotate independently, the outside tire can spin much faster than the inside wheel and thus (over)rotate the car. it will convert every steering input and there is nothing that keeps the rear in line. will do ams2 videos where we have cars with complete open diffs, or maybe lfs where we can put any diff with any value into any car
@@SimracingPopometer Thanks, I believe you, but don't understand. With a lsd dif there is some drag on one of the wheels (the inside because it has less grip?) caused by the clutch packs, kind of like putting a tiny bit of parking brake on that wheel. On an open dif there is no drag on either side, so 100% of the tire grip goes to lateral traction, so the rear has more grip, meaning less oversteery?
ah. in my unerstanding there's no "drag" with the LSD on the inside wheel in the form of a decelerating effect. the inside wheel doesn't turn slower because it wants to turn slower. it turns slower in response to the driver turning the steering wheel and being put on a different radius - the LSD allows the tire speeds to adapt to the rotation requested, it doesn't force the rotation. but the LSD limits the speed difference (it actually limits torque difference, but thats more abstract to think with), and this way doesn't allow the rear end to rotate faster than desired, it prevents the driver from being able to request too much and lose the rear. if anything the inside wheel is forced to rotate more than it is covering actual distance on track - thats what the limited difference between inside and outside tire enforces. with open diffs you'll see early throttle inputs to control the torque difference and keep the car stable. the formula inters in ams2 have an open diff, here's an irl onboard: ruclips.net/video/1bAzPJKwVzc/видео.html
watch how he needs to correct on the steering on every corner entry because the rear is willing to rotate more than the car could take and then watch how on throttle its perfectly stable (except last turn) and he can finally commit to the steering as excess torque from the engine would have the option to escape trough the inside wheel, no snappiness on exit as a result. But generally, the more steering he applies, the rear end of the car can always adapt and do the rotation. the car is never front limited, it steers with the rear essentially
@@SimracingPopometer Thanks for the reply. I'm was thinking about the total grip and as a thought experiment looked at in the extreme: if it was a welded diff it would increase understeer because the rear tires would want to keep it going in a straight line. However the rear would also have less total grip because the inside wheel would be slipping as it's speed is locked to the more weighted outer wheel, meaning some of it's overall grip is lost to this excess rotation. So overall the rear would have less grip, which leads to oversteer. So you might find it has understeer under the limit, but also a lower limit, so oversteers before an open diff.
In an LSD the two tires are not welded together, but there is a friction connection through the clutch packs, so, as with a welded diff, the overall grip is reduced, meaning, all other things being equal, an LSD will break loose/oversteer before an open diff.
yes agree with the first part and agree with the 2nd part under the condition that the allowed difference between the rear wheels is not enough in any given situation.
Hey Nils, I liked the music. Maybe u would consider it to put it in the background for the whole video but much quieter. Thanks for the education btw. 😊
the music is only 3-4 min long, would cause issues sooner or later, but yeah, perhaps needs more ambient :D
Na wer baggert da noch so spät am Baggerloch
Es ist Nils, der kommt nicht aus der Grube
Denn er hat sein Baggerdifferential gelockt
😹
First! Did I hear pie?! I'm super hungry now...😅😂