A lot of road car G forces seem to be off..

Yri · Mar 31, 2021

Hello, I am asking today about something I just noticed. I got a skidpad map and I was attempting to see the max g forces in an E92 M3 I could pull in a 300 foot circle. Turns out, instead of getting the real life .97 G, I got .84. This doesn't make any sense to me, and when I upped the grip a bit, to get to .97 g, it felt SO fast. Almost unrealistically fast. Same thing with the 0-60 times. I upped the rear grip and got way closer to the real life times, albeit with many attempts. I used the stock Assetto Corsa G force meter, so is the G force meter off or something?

Stereo · Mar 31, 2021

.97 is quite high for real life. Semislick tires type of thing on most production cars. If you have a specific car in mind that's tested at 0.97 maybe say what it is.

0-60 times aren't really matchable in AC so it's probably not worth being concerned.

Yri · Mar 31, 2021

Stereo said:
.97 is quite high for real life. Semislick tires type of thing on most production cars. If you have a specific car in mind that's tested at 0.97 maybe say what it is.

0-60 times aren't really matchable in AC so it's probably not worth being concerned.

The E92 M3 was quoted in 2010, by Car and Driver, was at 0.92 G. The most I can get, with fully warmed up tires, is 0.81 G. These were both executed on 300 foot skidpads. I'm not too concerned about 0-60 times, more of the lateral G is what I'm concerned about.

The Lexus RC F, was quoted in 2015 and 2016 at 0.93 G by cars.com. I attempted it, with my own special modifications, such as realistic weight, wheel power, etc to see what I would get. Turns out I only got 0.79 G on a 300 foot skidpad, exactly what Cars.com used. Upon turning the tiregrip up, I ended up getting 0.94 G, but it felt absolutely bonkers (or maybe I'm just used to having low grip). Keep in mind both of these runs were with semislick tires.

Gevatter · Mar 31, 2021

If you're down on cornering grip by roughly the same amount on several cars it could also be the track. Are you certain the skidpad surface you use produces the correct grip, or at least the same grip levels Car and Driver used in 2010? What ambient temperature was set and what track state was it in (green/fast/optimum)?

Yri · Mar 31, 2021

Gevatter said:
If you're down on cornering grip by roughly the same amount on several cars it could also be the track. Are you certain the skidpad surface you use produces the correct grip, or at least the same grip levels Car and Driver used in 2010? What ambient temperature was set and what track state was it in (green/fast/optimum)?

The settings were at optimum, ambient temperature 84 degrees Fahrenheit. Just checked the skidpad grip levels in the surfaces file, says its at 0.98. Changed that to 1.00, and the most I can get out of a stock E92 M3 is 0.85 G. Still, its closer to the real value but its not quite there.

garyjpaterson · Mar 31, 2021

surfaces grip 97, system grip at 99, getting ~0.95 G on the semis.

https://i.gyazo.com/82ccc5e14187bbb4571fda87be591f2e.gif

Yri · Mar 31, 2021

garyjpaterson said:
surfaces grip 97, system grip at 99, getting ~0.95 G on the semis.

https://i.gyazo.com/82ccc5e14187bbb4571fda87be591f2e.gif

What app is that? I might want to try that one and compare the two. I think based on your speedometer it says you are doing 22 kmh, or is it mph?

garyjpaterson · Mar 31, 2021

Yri said:
What app is that? I might want to try that one and compare the two. I think based on your speedometer it says you are doing 22 kmh, or is it mph?

Its the car physics app, available by activating dev apps.
No idea what the Fspeed value shows, its not in line with actual speeds (ie it lags behind a bit), Most likely metres per second but yeah, i wouldn't read into it.

Yri · Mar 31, 2021

garyjpaterson said:
Its the car physics app, available by activating dev apps.
No idea what the Fspeed value shows, its not in line with actual speeds (ie it lags behind a bit), Most likely metres per second but yeah, i wouldn't read into it.

Welp, it was just as I expected. The actual G meter, in the stock apps, is actually wrong, not sure why.

When using the G meter app, it was saying .75g lateral at 70kmh. When I turned on the car physics app, it said it was reading more of something along your lines, 0.95-0.96 G. Strange, isn't it?

Thank you all for your help. I'm currently trying to make a car as realistic as possible, and this was one of the problems I had.Thanks!

Neilski · Apr 1, 2021

Yri said:
Welp, it was just as I expected. The actual G meter, in the stock apps, is actually wrong, not sure why.

When using the G meter app, it was saying .75g lateral at 70kmh. When I turned on the car physics app, it said it was reading more of something along your lines, 0.95-0.96 G. Strange, isn't it?

Thank you all for your help. I'm currently trying to make a car as realistic as possible, and this was one of the problems I had.Thanks!

Yup, I dimly recall that this is a very long standing bug (and frankly a pretty damn bizarre one), but I can't immediately find the relevant thread on the official forum (or here).
"FSPEED" is indeed metres per second, IIRC, and it's one of the "filtered" (hence the F) bits of data that show up in the various apps.

Edit: found the thread on the AC forum. Turns out I actually created it, LOL. Precisely zero replies. Trivial to fix the bug though, if you want to, since it's in the gMeter.py file.