Physics discussion thread

I don't quite get the point of comparing a real life clip without any telemetry, inputs or weather informations to gameplay just by feeling if it the result looks the same.

I also don't understand how AMS2 can still be too Slidy by arguing the rear of the cars are too planted. Have we came full circle now that AMS2 is too understeery?

 

It's been a while since I drive an FWD car in AMS2, but even in PC2 days if you didn't respect the needs of an FWD car they were prone to lift-off oversteer and braking-induced oversteer (hence why you shouldn't trailbrake in them). What car were you testing in? I'll need to jump on and have a crack and see if I can make it misbehave.

Skip Barber's video was extremely helpful in correcting FWD errors - in simple terms, point front wheels where you want to go, and hard on the throttle

 

A few months ago I was objectively trying to work out why people say it is too slidey and compared primarily to R3E and ACC. I determined that it was 100% because the other sims tended towards understeer (especially ACC as well as AC, which I played a fair bit in the past) and that's what everyone is used to. For me the "slidiness" was comparatively far worse in ACC but instead of being the rear it was the front.

So people are always going to compare to what they're used to. I'll reiterate what I've said in the past - the skill transfer between all these modern sims (no matter their characteristics) is so miniscule that getting fast in one and then fast in another is merely a matter of time and practice. I can jump between pretty much any sim with comparable (and realistic) tracks and cars and almost always set times within 2-3 seconds of each other after a couple of laps to get my eye in.

I actually haven't done any racing in AMS2 since the latest update as I've been busy with other things but I will be making the time to change that today

 

If you use telemetry HUD, we have tons of longitudinal and lateral G FORCEs in up right gadget and a lot of compression in suspension working like it's suposed to do, and If you keep wheel in the same position, in cars without aero, tons of grip going to front tyres when braking.

But I can't trail braking right, as obviously can't drift too, so, I'll not record a video to display my lack of driving hability!

 

I tried to replicate the same in AMS2 as he did in the video, and I agree that cars don't "dive into the corner and hook front tires into the ground on corner entry" to the same degree in AMS2 as in other sims such as AMS1, Assetto Corsa, and iRacing. But it doesn't feel as extreme to me as he's describing it in the video, as if one has to overturn the wheel or else there will just be understeer on braking.

Judge for yourself how I do Turn 1 in my video - I do use slightly more steering input than he uses in AMS1, but I'm using less than he does in AMS2 (I use roughly 40-45 degrees, while he initially tries less than me but increases to 75-90 degrees mid-turn. I was using automatic shifting and auto-blip, which can disturb the pedal display in the HUD a bit, sorry about that.

One related observation, though: While in AMS1 you get a lot of turn-in rotation on heavy braking, in AMS2 to me it seems that in most cars the rotation comes upon shifting from heavy braking to trail-braking. If you need the car to turn in directly on braking, it will only do so if you don't brake too hard. Maybe this is what causes the people looking for a specific type of "tires hook into the ground on corner entry" behavior to exaggerate their inputs in AMS2.

 

As a follow-up to this (I think the forums went down immediately after my post when I was testing) I ended up testing the new and old Minis, and the VW Polo. I did everything I could to destabilise the cars (with and without assists) but I definitely wasn't easily able to make them oversteer with either lifting or braking. I don't know if it's a setup thing, but generally I would end up understeering straight off the road in a situation that I would have thought would have lightened the rear. So perhaps these cars are inherently more stable despite being FWD.

My IRL comparison is my own daily driver - a Ford Focus ST. When I first got it, it had terrible tyres all round and had pretty bad lift-off oversteer in the wet. Since replacing those tyres though it's never been an issue and never in the dry (despite trying to push it at times in the wet). So perhaps there are other factors at play here, and maybe someone with actual IRL FWD race car experience could contribute their opinions.

 

I just wanted to give an update on my post. I think it would have been better if it stayed in the original topic. I wasn't trying to be negative but clearly something wasn't right.

I managed to completely eliminate the slidey/floaty effect by reducing the throttle/brake sensitivity from the default 50% to 5%. In steam input I also set the anti-deadzone of my steering stick to 9000 (about 30%). I read a post that deadzones are coded into the input. I don't know if it's true or not but the steering became so much better. Modifiying these two settings was a complete game changer. Now my input responses feel more or less like any other race sims I've played. And compared to before it's like playing a totally different game. Absolutely no more weird sliding, floating effects. Before I had gameplay TC and ABS assists on low, now I turned them off completely. Driving in the rain is not a problem anymore, although it's still more challenging than in other sims. Base setups feel great, and depending on the TC/ABS level I use, the game still feels challenging.

For anyone who is struggling on a gamepad, here are the settings I'm using.

Wheel - Legacy - Steering rate 100 - Steering lock 360 (using wheel instead of controller setting seems to work better)

Throttle/brake sensitivity 5
Steering sensitivity 50.
In game deadzones all 0.
All other sensitivities including damping & speed 0.
Steam input anti-deadzone 9000.

I think the person in the video is dealing with some input issues. Best of luck.

 

IMO the problem has been the opposite, at least prior to few latest updates where the rear just becomes too light from the car diving on braking and you ended facing the wrong way very easily.

But it's also true that the car tend to understeer on braking very easily (depending on car and how it's setup) if you apply too much braking and have more front BB. I didn't find myself needing to use brake to get the car turn enough that often on AMS2, the fronts have been strong enough for that.

I think this has changed considerably in last few months, with some cars/classes more than others. Now the balance is more towards understeer if you while trying to trail brake too hard rather than making rear flip on you and you tend to require a bit more help from trail braking than you did before to get the ideal rotation.

Brake sensitivity is something I personally use to make it easier for me to trail brake without applying too much braking and I adjust sometimes per car.

It's for sure different on weight transfer feels compared to some other sims. Sometimes it feels like it's "slower", not as abrupt as in some other sims, example when you get on throttle, the car doesn't start to understeer that immediately (or much at all) and you might feel the car sliding more instead of rears biting, when you start ease of the brakes, the front stays loaded longer (which can lead to oversteer with rears not regaining enough grip fast enough). In other sims I have played, applying brakes or throttle feels like it impacts the balance more immediately. I think it can make it feel as there is "less" weight transfer on AMS2, but I don't that is the case. If somebody has time and enought understanding, I would love to see some proper analysis / comparison based on telemetry data if either of these things are true or not (amount of weight transfer and how fast it happens on AMS2 vs some other sims). Could be that it's only because the cars have used to be much more rear limited in AMS2, while in other sims it's often the otherway around.

 

A bit difficult for me to make a broad comment on all vehicles, since there's such a big variation of vehicle types in AMS2, but for example in the case of the F-Vee and F-Inter, the behavior you describe could also be due to strong engine braking and that some maintenance throttle is needed to keep the rear stable in those situations, compounded with a very loose rear differential and wobbly rear suspension.

 

Yep and even in other cars, the behavior can be caused by other things that just make it seem like there is something weird or different with weight transfer, like the differential you mentioned in F-Vee/F-Inter, which was one of things that god adjusted in some cars this fall (GT3 for example).

 

Just watched the video, the analysis and the conclusions of the Youtuber are flawed, IMHO.
I used to own a Honda Fit and did a few auto-x events with it for fun. A stock Honda Fit is an understeering PIG, on the stock suspension if you try to brake and turn it will overwhelm the front tires and understeer very easily. I have a few buddies that race FWD cars IRL and we discuss setups all the time. Fits that have been modified for racing have a lot of tweaks done to their suspension to completely change the way they handle. Stiffer springs in the rear, massive swaybars in the rear and toe out in the rear, which makes the car super nervous on corner entry. Also the Fit comes with a very close ratio steering rack from the factory, so it doesn't take much to initiate a turn, one of the things I really liked about the car. A proper test would've been to setup the cars similarly across all games and see how closely they mimic real life.
The video comparison is like apples to oranges unfortunately.

In real life, most cars will overload the front tires pretty easily under full braking. When you try to initiate a turn in that state, you'll end up understeering because the front tires don't have anymore grip to give you. The way to start a turn is by slightly lifting off the brake to free up some grip in the front tires and turn the wheel. That freed up grip is then used to turn the car. While on track, this is usually the most dangerous and hardest phase of cornering, because you have dynamically shifted most of your grip to the front of the car and rears have less overall grip which usually puts the car into an oversteer phase. I've seen drivers lose the rear during that trailbrake and turn in phase and end up into the wall, perhaps due to an aggressive setup or lack of skill or a combination of the two IRL. Just last year I saw a Honda S2k and a ND Miata hit the inside wall in T1 of High Plains Raceway.

I guess what I'm trying to say is
Partial/trail braking + turning = oversteer (depending on car setup and conditions)
Full braking + turning = understeer (most of the times regardless of FWD or RWD or AWD).

 

The Copa Uno is pretty frisky, you can get the back end out no bother.

 

AMS2 physics simulation works exactly as you described. It's a good sign, I guess. I tested exactly this doing all sort of stupid things in some ovals with a lot of cars.

 

Apparently 22 years of real world amatuer motorsports will teach you a few things along the way. Man I feel old. LOL

 

I drove this strange thing for some years, and I think almost dying sliding in four wheels in traffic sometimes gives me limited feedback about "slide feeling" and weight transfer for sure:

Gurgel BR-800 – Wikipédia, a enciclopédia livre

We are not old, it's called "experience"...

 

Never heard of the Gurgel 800 but it looks fun, we need it in AMS2!

 

I think I saw a review here with a similar complaint from a real McLaren driver. I think he also said the car doesn't drive quite right in AMC2, like a circle. It's best to rewatch the original.

Could you demonstrate the maneuvers you described in other games? I'd do it myself, for example in ACC, but my skills need to be better to make the driving as "bad" as necessary. It's very interesting to compare your theory with inability to drive. A car's behavior should be equally predictable and logical regardless of skill, right?

I can add that the sliding remains just as unpredictable as before the update. I can drive the Stock Car 2024 Cruse with 10-15% left front wheel play for a few laps on the Cascavel, but with a properly warmed-up tire, I'll spin out (spin) in a strange but common situation. Yes, this could be attributed to my SRP Lite pedals, but the telemetry shows nothing out of the ordinary—not the temperature, not the wear, and not the steering abruptness. There are many nuances to discuss regarding the physics and the logic model, but for that, we need a reference—someone who has driven the vehicle in question and experienced its behavior in-game. The update is still too recent. I've posted one of the options in another post above.

 

T

This is a very old video, and has been litigated over and over as to what he did and didn’t do which let himself ( who most of us respect his pov ) and Ams2 down.
Let’s just move on , the cars drive nothing like this example.

 

Let me say right away, I'm not a professional, I'm just a hobbyist... But! I saw several comments and additions to your video. And I think I saw something none of you noticed when delving into the details and theory of the process: I saw visual physics, or more precisely, the inertia of entering a turn.

"Yes, we know that the cars are different, not a standard for comparison." - but it is clearly visible.
- In AMS1, the car's body, i.e., its weight, and the suspension's interaction with it, have a very noticeable effect on the car's turn. This effect is then noticeably transferred to the wheels, which cope with it. (A very noticeable example)
- In AMS2 this effect works differently, it seems the car is more like an iron going into a turn sideways, as if the axles are working equally under load, and the rear axle is trying to catch up, or rather fly somewhere ahead, the influence of weight is not felt in any element.
- In a real car, the overall weight of the car is felt more strongly, which is especially noticeable during braking. There's no significant body roll, there's high speed and understeer, but the car skids completely differently, following the trajectory of inertia, with minimal skidding; it simply loses traction. (This seems similar to how physics works in AS.)

I don't know how the physics system is made in AMS2, but it seems there is an analyzing (predictive) line that works somehow incorrectly, not only on this car XD

It's really interesting to learn how the physics in the game are developed, what principles they use! So I can understand what might be wrong with the game... I've seen this process even in BeamNG, but not here. Is there a reference car from which they take telemetry and drive in real life? There must be several.

I think this video will be useful to someone.

 

This is becoming like a greatest hits of irrelevant old videos.