open differential FWD

[Bandit77]

Just a question: Is the open-diff behavior thought to be realistic or was its development neglected because nobody uses it anyway (exept for UF1-drivers)?
Correct me if I'm wrong - but most production FWDs do have open diffs, right? So which ones of these do rev up like mad in a tight (or even not so tight) turn sending all the enginepower to the inner wheel leaving you almost without any propulsion (is that the word?) and a lot (just way too much) understeer. LFS does exactly this, which I NEVER experienced in RL... and I'm definitely no stranger to chasing FWDs (including a '96 Cinquecento with a very short wheelbase) thru upwards serpentines - fighting against powerundersteer of course, but it's never that hilarious.

Anyone RL experience with a behavior like that?

[atledreier]

Every day in my Passat, my Touran, my Polo, and before in my Mazda 323, in an old Honda and basically any fwd car I have driven.

[tristancliffe]

Yes, in most FWD cars when you drive hard.

[Rubenz81]

Uh... i found the open diff in fwd pretty real in lfs; bear in mind that setup and aggressive driving "exaggerate" the understeer of the car. In real life you wouldnt push to the limit as on lfs... or real life racing :D

Not so long ago i experimented with XFG to match behaviour peugeot 205gr.n in rallycross. It was amazing how with a similar settings the xrg behaved. In fern bay rallycross x it was like racing with the 205 on rallycross. This really showed how good lfs is... power understeer, weight transfers... was really realistic to be a game. Ehrm. A sim. :D

[Alric]

Yes I also agree. LFS does a fantastic job at simulating open diffs. In real life I have driven many FWD cars that spin the inside wheel. When i owned a Honda Integra Type R with a helical LSD however it really showed up how bad most FWD cars really are.

[Bandit77]

ok, I finally have to see that I live in a parallel universe or something.:shrug:

[Nathan_French_14]

Its not abnormal for a FWD to spin the inside wheel. My dads accord type-r does it, my brothers V6 mondeo does it. Even my sisters ford puma does it :D

Maybe it depends on how you enter the corner. The inside wheel would be more likely to spin if your throwing it into the corner instead of going smooth and progressive.

[Bandit77]

Actually, in my mediocre understanding of physics, the inner frontwheel of an FWD is most likely to lift off / spin if you accelerate hard out of a bend. the acceleration moves the weight to the rear, while centripetal-force moves the weight to the outside. result: no weight on front inner wheel.
so far so good. but in my universe this doesn't happen that extremely. most of all not in almost every turn you do or if you just turn in a continuous circle in 1st gear.
and IF it ever happened it would surely not last like a second and the revs wouldn't hit the limiter.

but as I said. maybe that's just in my universe. but luckily i'm not alone there :D.

http://www.youtube.com/watch?v=FZIHpa5zyPs
http://www.youtube.com/watch?v=TXtmILKF1mg

[tristancliffe]

I think you mean LACK of centripetal force ;)

And I think maybe you're not driving hard enough (which is a good thing on public roads).

When it happens, it can last several seconds (depending on length of turn, radius, speed and vehicle wheel torque), and yes it can hit the rev limiter.

Also, you drive a lot harder in LFS than you do in real life.

[Crash Dummy]

My 1988 Nissan Pulsar (sunny) with all of it's 78hp will spin up the inside wheel leaving you going nowhere fast at all. Try to do a standing start with the wheels turn in the wet and you can actually find yourself going nowhere as the inside wheel spins up as if it's nearly in the air.
I've also driven a modified car that matches the FXO for power to weight, 2.0l turbo FWD and it has an open diff. That's an experience. Don't use much throttle unless your going dead straight in that one unless you want to instantly transform the inside tyre from a solid to gas :nod:

[Bandit77]

I think you mean LACK of centripetal force

no, actually I meant centrifugal force.


Also, you drive a lot harder in LFS than you do in real life.

of course I considered that. but even if I go quickish rather than fast on the limit in LFS the inner wheel spins like mad.

I mentioned the 1st-gear-full-throttle-circle... did that with a cinquecento-cookie-box because we had to find a noise. no spin. go do this with the UF1.

and have you seen the vids? don't think they move slow. if you go like this in LFS with an open diff you have constant spin.

I certainly do not compare LFS-driving to my everyday driving. but I also mentioned the uphill serpentines: that's probably THE situation for an inner front-wheel to lose traction... and it does but it's minimal in real life.
guys, I've chased uphill thru bends with squeeling tyres and throttle to the metal... no spin like that.

come to my universe... :D

[Shotglass]

Yes I also agree. LFS does a fantastic job at simulating open diffs.

except for one important feedback ... no gear whine when one wheel slips

[tristancliffe]

no, actually I meant centrifugal force.It is a LACK of centripetal force that causes load transfer, you to slide to the outside, and your milk to fall over whilst cornering.

Centrifugal isn't the cause.

[Rubenz81]

Bandit:- Come to my rallycross universe where mud and gravel makes your life hell with open diffs then! :D
I see your point, maybe lfs has way more power understeer on open diffs than real life but... setup it's a big point in that, as i sayd before i spent some time to do a set for xfg to match one of a 205gr.n i drived and really it was much fun and very realistic (still we are talking about a game...). Maybe on the less powered cars (Uf1) it wont be so pronounced as 50hp cars... ehrm dont spin too much.
Hmmm now that it comes to mind my sister Y10 it's a clear example of a very underpowered understeer car with a completely wrong setup even for normal driving. So i contraddict myself :).
I think you can notice this problem more in high speed turns where the less powered cars shouldnt understeer too much and of course on tarmac! (On mud and gravel, it's a completely different story and here lfs it's really fun)
So yes lfs it's not perfect, but i dont see this as a BIG lfs hole in physics more like something that needs a small small tweak.

[Ball Bearing Turbo]

except for one important feedback ... no gear whine when one wheel slips

Take the XFR out with an open diff, and report back ;)

Any time the trans spins up in LFS, there is gearwhine.

Re main topic:
LFS acts perfectly logical, there is no "modelling" of this circumstance - if a driven wheel loses traction, it will spin just like IRL.

No LSD of sorts, and you will spin the inside wheel like crazy, even in a RWD just slightly less so. I've done this even in my wimpy car without even meaning to, just doing a U-turn with medium throttle, no squealing, but up went the tach and I was actually surprized.

In my boss' old car with 250lb of torque, it was insanely easy to light up the inside tire.

So, throw setups and not feeling G forces on your carcass into the mix and LFS feels the way it does. The tires have plenty of long grip, so it is what it is.

And Centrifugal force does not exist :razz:

[Bandit77]

It is a LACK of centripetal force that causes load transfer, you to slide to the outside, and your milk to fall over whilst cornering.

Centrifugal isn't the cause.


if you want to be a smart-ass, then tell me why the LACK of centripetal force doesn't lift my wheels when bolting down a straight... :razz:

the lack of a force moves something... that's interesting, really.


the thing is, in RL the open diff is kind of self-regulating:
- weight moves towards outer rear tyre because of "cornering forces" (to avoid highly technical expressions) and acceleration
-> loss of traction or even lift of inner front tyre
-> open diff sends power to inner front tyre
-> power distribution leads to understeer
- less propulsion in general due to suboptimal power distribution (and traction)
-> less acceleration
-> weight shifts back a bit to front and inside (because of increasing corner-radius)
-> increase of traction on inner front tyre (and outer)
-> more acceleration and decrease of corner-radius
- start over

so that's basically what happens with a FWD in a corner and what I experience in RL. just in RL this is really smooth and kind of subtle (only the amount of understeer can vary a lot from one car to another).
and yes, in LFS it's basically the same, just way more extreme and it feels like the weight never gets back from the outer rear tyre and the inner front tyre is floating unless you release the throttle quite a bit. applying full throttle in a bend is more or less impossible.

if I take the XFG with one of my race setups and alter the diff from blocked to open, it handles like what I would expect of a car that has a combination of

- a suicidal high center of gravity
- tyres that have such a high level of grip that you could flip your car by just cornering it
- a whole lot of power and little engine weight
- a tiny wheelbase
- a bloody bad suspension with a lot of body roll and too hard a front

and again: if I drive an LFS-FWD the way I drive an FWD in RL, I have to fight with extreme power loss and wheelspin whereas in RL there's no spin at all.

i mean, watch the vids. if you say they're moving slower than me in LFS doing an easy lap on a cruise-server, then somebody call a doctor... when he's here we can decide whether I or you need his help... ;-))

[AndroidXP]

You take a quasi-exploit locked diff setup that relies on the inner front wheel to lift to work, change it to an open diff and wonder how it doesn't behave like "a real car" (which you don't even know as I can guarantee you no real car uses a setup like that). Granted, real cars aren't nearly as stiff as the ones we have in LFS, so the bending car might counteract lifting the wheel a bit, too, but saying that LFS physics are completely from a different universe is nonsense.

Consider that in LFS the main driving feedback is visual. If you do something that increases or decreases the cornering force in such a way that would cause immediate reaction or notice in real life, you can barely even see a difference in the speed the camera rotates, if any at all.

[Bandit77]

You take a quasi-exploit locked diff setup that relies on the inner front wheel to lift to work, change it to an open diff and wonder how it doesn't behave like "a real car" (which you don't even know as I can guarantee you no real car uses a setup like that).

with bob smith's "road going" setups the effect is even worse. don't distract from the main issue - it's the same with the UF1 standard setups. believe me, the XFG setup I made to try to prove myself that LFS isn't that far off was tweaked in order to prevent wheel lifting.
I just tried blackwood, and in the first 3rd gear righthander i can "lift" the wheel when driving on the ideal racing-line with 80 kph... just floor the throttle and there you go.
as i'm not that incredibly fast in LFS I usually take this corner with maybe 110 kph... therefore I strongly believe in RL I sometimes take corners like those with about 90 kph flooring the throttle midcorner... no spin.

then I took a ride in south city, rolled slowly to a 90° lefthander, took the tightest radius possible (kind of like in real life traffic). so I turned with 30 kph, then floored midcorner. biiiiiig wheelspin and rev-limiter hitting. I then thought, ok, you wouldn't do that in 1st gear, although this setup's 1st gear goes to probably 70 kph. so I did it again in 2nd - just like turn into a crossing street. no rev-limiter hitting but still some raise in revs and wheelspin. you DEFINITELY don't get this in RL with an average car.


I mean, those of you who say it's absolutely (or at least highly) realistic - did you really compare or do you just believe in the high accuracy of LFS and search for all possible reasons why the subjective experience might differ? after all it's just another bandit-thread and he's always wrong until proven right. :razz:


for the record: just drove the FXO standard-setup with patch x30, which uses an LSD. now THIS feels much more like an open diff FWD in my universe.

... and now it's late and I spend far too much time with LFS.

[Ball Bearing Turbo]

Look, this isn't rocket science :shrug:

Look at the G meter when you're getting wheelspin in LFS. LOOK at it.

Then think to yourself "Bandit77, with a car pulling a G or so, A) how much weight is acting on the inside tire, even including the spring, and B) how much torque am I attempting to transfer through said tire?".

If you don't get it then, then I give up. Get a Force Dynamics and feel what's happening I guess.

[thisnameistaken]

Why are we even arguing about what FWDs do? It's not like anybody actually drives them in LFS is it?

[Glenn67]

- a bloody bad suspension with a lot of body roll and too hard a front

Well that statment might fit with chassis flex not being modeled yet, chassis flex has a big impact. Irl they deliberately take measure to reduce its effects in race preped cars so should make a noticable difference to road car type handling when it is implemented at some future stage :shrug:

[Impreza WRX]

Been there, done that. 2003 Chevrolet Cavalier. Spins inside wheel when WOT and turning (which is hard on CV axles BTW), has horrible suspension that makes the car roll into it, and the absolutely atrocious chassis flex doesn't help either.

If the Civic's chassis strength can be equated to a beer can, the Cavalier, in comparison, is a paper bag.

[Shotglass]

Take the XFR out with an open diff, and report back ;)

Any time the trans spins up in LFS, there is gearwhine.

i know but thats not what i meant
the gears inside an open diff are cut staight so everytime the diff slips youll hear it over the (lack of in case of a road car) transmission whine

LFS acts perfectly logical, there is no "modelling" of this circumstance - if a driven wheel loses traction, it will spin just like IRL.

No LSD of sorts, and you will spin the inside wheel like crazy, even in a RWD just slightly less so.

it just occured to me that in lfs maybe the open diffs are just a tad too open too idealised

[atledreier]

Come to think of it, my 60hp Polo is far worse than my 230hp Passat, so it might be mostly due to wimpy and poor suspension design and tires. Both have open diffs, but the Polo is soft and wobbly with a weak engine, no rollbars, whereas the Passat is low, stiff, wide grippy tires. That said, the Polo don't have the power to light up the inside front in 3rd unless I'm really trying. 1st and 2nd it does though. The passat can light up the inside front in any gear when driven hard, but I guess 380Nm to the front will do that to any tire. But the passat needs alot more torque to actually break the tire free. So bandit, maybe you have a very good suspension setup combined with not too much torque. That would describe your situation.

[Flotch]

atledreier : my 1989 polo fancy with its 40 bhp has a front antiroll bar, sound strange yours does not have one :scratchch

[atledreier]

Yeah, it might have one, but it sure feels like it's not there. That's beside the point though, really. Even my wife will occationally spin the inside front with normal driving.

[March Hare]

if you want to be a smart-ass, then tell me why the LACK of centripetal force doesn't lift my wheels when bolting down a straight... :razz:

the lack of a force moves something... that's interesting, really.

Reattend your physics course.

To turn (move in a NOT straight line) reguires a force. If that force is not strong enough you will not turn enough. A turning car recieves that force from the friction between the road surface and the tyres. Because the contact patch between the tyres and road is lower than the COG (centre of gravity) of the car the friction force creates a torque force that results in making the car lean.

For a vehicle (or any particle) to travel in a straight line the sum of all lateral forces must be zero. Otherwise the path will be curved.


A easy and safe test to figure this out is:
You need a clear table (one that is not cluttered with junk).
A piece of paper (A4 size or similar, not glossy).
A top heavy plastic cup or other similar nonbreaking piece of equipment that has its COG high.

Put the piece of paper on the table. Put the topheavy cup on it.
Now yank the paper from under the topheavy cup.
Notice in which direction the cup falls. It falls to the opposite direction from the one you pulled the paper to. How is this possible?
The reason is the same as when a car leans in a turn.
Torque.

Disclaimer: Simplified explanation that does not take the suspensions roll center into account. And when I'm talking about torque I don't mean the engines torque.

[Bandit77]

Look at the G meter when you're getting wheelspin in LFS. LOOK at it.

Then think to yourself "Bandit77, with a car pulling a G or so, A) how much weight is acting on the inside tire, even including the spring, and B) how much torque am I attempting to transfer through said tire?".


done that. when doing the "turn in to a street" thing with way less than 50 kph, only 0.5 G's (sideways) with 0.2 G's are needed to rev it up like mad. ha, hilarious.

in faster corners you will need 0.6 G's - most obviously because you don't accelerate that hard.

and that's with a XFG with a setup as stiff as you wouldn't have in a production car. softer setups make it worse - see UF1.

hmmm... I really do think I've driven thru one or two bends IRL with that g-load and had no spin (and most of all reving-up) like that.

and I think that swift chasing the f40 in the video does a couple of turns above 0.5 G, too. now isn't the XFG said to be very close to the swift?

case closed for me. thanks for the hint. :razz:

but I guess 380Nm to the front will do that to any tire. But the passat needs alot more torque to actually break the tire free. So bandit, maybe you have a very good suspension setup combined with not too much torque. That would describe your situation.

first of all, the engine-torque at the shaft doesn't have a direct impact on the wheels at all. just as sidenote. let's just keep it simple: the passat sure has more balls. :D

well, I can't really complain about the suspension of my present car, but I've driven a of other FWDs, stiffer and softer, more and less powerful than mine. same thing: you might get different degrees of powerundersteer, but hitting the rev-limiter? no way, maybe on slippery surfaces but then the other wheel spins too.

but yeah, the last possibility would be that there wasn't one single car among them that was sh!tty enough to act like an XFG.



it just occured to me that in lfs maybe the open diffs are just a tad too open too idealised

what I'm saying. that's most probably why the FXO with the standard LSD setting comes closer to a reallife open diff.
now actually, the initial question is still not answered: will this be fixed or neglected as it's underused anyway. :D

...

not that your essay isn't correct - but I think you missed the point (or may I say punchline) in that little side-argument.

[March Hare]

I miss a lot of things. Especially apexes.

[Bandit77]

I miss a lot of things. Especially apexes.

:D nice one :thumbsup:

[Bob Smith]

done that. when doing the "turn in to a street" thing with way less than 50 kph, only 0.5 G's (sideways) with 0.2 G's are needed to rev it up like mad. ha, hilarious.

in faster corners you will need 0.6 G's - most obviously because you don't accelerate that hard.
The vast majority of road driving is done at under 0.3gs.

[ajp71]

You need to take into account that LFS cars are infinitely stiff and will not flex at all like a RL car, then that any LFS racing setup is far far stiffer than you'd run in a road car and due to the bumpy nature of real tracks far stiffer than your likely to run IRL in a production car. Then take into account that most setups are still designed for locked diff exploits, as Android pointed out they have to lift a wheel to work. I think LFS's tire scrubbing/slipping sounds maybe slightly exaggerated still, so that'll make you more aware of what's going on. Lastly your driving the thing far harder than IRL.

Until you have an accurately setup car you can't even start to analysis the diffs anyway.

[kaynd]

There is not one thing to be fixed (eg understeer in FWD)… tire model needs to be excelled in general. Also suspension and chassis flex… (it is more likely that we wont see chassis flex ever in LFS)
There is nothing completely wrong that lfs’s engine is simulating now… it may be a bit overdone in some ways but not completely wrong…
Also to prevent front wheel spin you do not need only a hard setup in general but higher or a lot higher rear roll resistance that in front.
Do you mind sharing the setups you used while testing the wheelspin behavior?

One of my friends happen to own a 93 swift GTI and I know it spins it's front tires like crazy...

[Bob Smith]

Chassis flex an modern cars (from what I've read) generally never exceeds a half a degree, even during the most extreme cirumstances, so it's affect seems pretty minimal on monocoque design cars.

[Bandit77]

The vast majority of road driving is done at under 0.3gs.

I wouldn't doubt this a second.

By the way, Bob, far off topic but I have to say this: I LOVE your "road going" setups. Gave me a good starting point for making a drivable LX-setup. :thumbsup:

You need to take into account that LFS cars are infinitely stiff and will not flex at all like a RL car, then that any LFS racing setup is far far stiffer than you'd run in a road car and due to the bumpy nature of real tracks far stiffer than your likely to run IRL in a production car. Then take into account that most setups are still designed for locked diff exploits, as Android pointed out they have to lift a wheel to work. I think LFS's tire scrubbing/slipping sounds maybe slightly exaggerated still, so that'll make you more aware of what's going on. Lastly your driving the thing far harder than IRL.

Until you have an accurately setup car you can't even start to analysis the diffs anyway.

So this means a softer setup might reduce this nasty effect? In my understanding this is right unless the car dives to much on the rear. This however would mean you need to have a soft suspension in the front an a relatively stiff one in the back, which is definitely not production car style.

There is not one thing to be fixed (eg understeer in FWD)… tire model needs to be excelled in general. Also suspension and chassis flex… (it is more likely that we wont see chassis flex ever in LFS)
There is nothing completely wrong that lfs’s engine is simulating now… it may be a bit overdone in some ways but not completely wrong…
Also to prevent front wheel spin you do not need only a hard setup in general but higher or a lot higher rear roll resistance that in front.
Do you mind sharing the setups you used while testing the wheelspin behavior?


I'll get a setup for you. But you don't even need it because the UF1's standard set is kind of illustration enough.

I'm a suspension-softy :D, and curing the (IMHO) exaggerated diff behavior means stiffen up the rear to an unsound level.


One of my friends happen to own a 93 swift GTI and I know it spins it's front tires like crazy...

I just did some turns with my car about half an hour ago, and yes, it is possible, but you have to hit the throttle like an idiot and even then it's not as nasty as it is in LFS. So basically it's my well trained right foot that has prevented my inner front wheel from spinning for all these years :D, but IF I floor it, the effect isn't nearly as aggravating as in LFS.

So in the end, the wheelspin-thing is overpresent (couldn't find a better word). If it's because of the diff (which I believe) or any other shortcomings is probably not detectable for us.

I mean, if I can't say the diff is crap because I don't know if the causes lie elsewhere, how can you say it's accurate without nowing if all the rest that affects this phenomena is sorted out?


hmm... damn long post considering the fact that for me this case is closed... hehehe.

[tristancliffe]

if you want to be a smart-ass, then tell me why the LACK of centripetal force doesn't lift my wheels when bolting down a straight... :razz:Sorry, but I don't understand. In a straight line there is no force to lift your wheels, and the rest of the car isn't turning either....

the lack of a force moves something... that's interesting, really.You know when you go round a corner, and your shopping falls over? That's a LACK of cornering force on your shopping. Your car goes round the corner, but your shopping wants to continue in a straight line - it can't, so it falls over. Same with leaning to the outside and pressing against your door cards, or the load in your car as the car turns - things WANT to carry on in a straight line. So, ultimately, it is a lack of force that causes body roll, and the body roll (combined with complex interactions in the suspension, chassis etc) causes a tyre to lift up. Simple.

Go back to physics school (primary school level) and they'll teach you this.[/quote]

[Bandit77]

You know when you go round a corner, and your shopping falls over? That's a LACK of cornering force on your shopping.


in the second place.
if there's no force attacking the shopping, the a LACK of another force can't make them fall over.


but your shopping wants to continue in a straight line - it can't, so it falls over.

that comes first. THIS force causes the shopping to fall over.


Go back to physics school (primary school level) and they'll teach you this.

will you accompany me? they might even tell you that building a house shouldn't be started with tayloring the roof.


Sorry, but I don't understand. In a straight ...


Maybe you do now.

[Ball Bearing Turbo]

in the second place.
if there's no force attacking the shopping, the a LACK of another force can't make them fall over.
...
that comes first. THIS force causes the shopping to fall over.

So then, what force causes the shopping to fall over? Please describe the force acting on it, causing it to fall over (other than gravity). I'll even make a space for your description:

.
.
.
.

The problem is that there isn't any (or rather enough) force acting on it to cause it to follow the path of the cart. Therefore it's a lack of force acting on it in relation to the cart, and it falls over.

The diff thing is one thing, but this argument is cementing your stupidity quite nicely.

[Bandit77]

...

:D:D:D

if you think you're right and I'm wrong - f. it! I don't care.
if you think you've won an argument because I won't answer to this anymore - so be it. I don't care. I don't feel bad because of this... but I hope it makes you feel better.

I don't win anything by convincing you, so f. it again. If you want to just ignore the core issues of what I'm saying - be my guest. It just shows that there's no point in talking / writing to you.

[Shotglass]

You know when you go round a corner, and your shopping falls over? That's a LACK of cornering force on your shopping. Your car goes round the corner, but your shopping wants to continue in a straight line - it can't, so it falls over. Same with leaning to the outside and pressing against your door cards, or the load in your car as the car turns - things WANT to carry on in a straight line. So, ultimately, it is a lack of force that causes body roll, and the body roll (combined with complex interactions in the suspension, chassis etc) causes a tyre to lift up. Simple.

but why would you look at the forces acting on the car from a stationary observers pov instead of coordinates attached to the car?

[Rubenz81]

Me skips the force/physics/whatever/highiq argument.
So basically the lack of (slight as was stated before) chassis flex it's the problem of the high understeer of lfs on tarmac? How it could be improved?
And most of all how it could be improved leaving unaltered the current behaviour of lfs on mud/gravel?
Because i think lfs feels almost perfect in the fwd understeer department on slippery surfaces.

[March Hare]

but why would you look at the forces acting on the car from a stationary observers pov instead of coordinates attached to the car?
There isn't any difference.
Except for notation. Untill you reach the speeds that require relativity to be taken into account.

Bandit77, you sure know your physics.:thumb:

[kaynd]

So basically the lack of (slight as was stated before) chassis flex it's the problem of the high understeer of lfs on tarmac? How it could be improved?


No, chassis flex on its own will it make it even worse.
Now the granit rigid chassis gives the ability to utilitize the full potential of your suspension setup.
I think it is more about the tire model that will improve any kind of unnatural behaviour.
Anyway I don't think that there is extreme under steer now on the FWD cars... you can do pretty match whatever you want, regarding the vehicles basic characteristics, with a proper setup.
It is normal for a front weighted car to be generally understeery...

[w126]

There isn't any difference.Well, one is an inertial reference frame, the other is not.

[March Hare]

Well, one is an inertial reference frame, the other is not.

Our planet is orbiting the Sun. Our solar system is orbiting the center of the Milkyway. Our galaxy is whizzing through space at a mindboggling speed. But it all depends on how accurate you want to be.

The fact of the matter is that there is no force acting on the car to "throw it off the track". And your shopping that toples over because of your driving. Is not acted upon by some arbitrary fictional force. It is just trying to keep going straight when it's surroundings are taking a curved path. The reason it toples over and doesn't slam into your door, is the friction between it and the seat.

Another exaple of the same phenomena (WYSINWYG) is when you hit a a wall with a car. The car stops but you keep going untill the seatbelts/steeringwheel/wall stops you. Same for the Firstaid kit on your parcelshelf. There is no WallForce the drag it forward. It's the LACK of a stopping force that makes it fly forward. Untill, ofcourse, it hits the back of your head. Then it is acted upon by a force and slows down.

[Shotglass]

There isn't any difference.
Except for notation. Untill you reach the speeds that require relativity to be taken into account.

yes there is since in the static frame will have centripetal forces and inertia acting on everything that isnt bolted to the car whereas in the car frame youll suddenly find centrifugal forces acting on everything

[March Hare]

Yes the sign(+ -) changes to make the equations look nicer and lead people to misunderstand physics.

But the facts don't.

Choosing the right inertial frame of reference can make the sun orbit the earth. Do you think that is a fact? Or just a misinterpretation?

[ajp71]

So this means a softer setup might reduce this nasty effect? In my understanding this is right unless the car dives to much on the rear. This however would mean you need to have a soft suspension in the front an a relatively stiff one in the back, which is definitely not production car style.

No a correctly setup car in a non-rigid body physics model is what you need, unfortunately no bodies managed to make a sufficiently detailed real time program to do this task and I can't see it happening in the near future either.

[Rubenz81]

...
Thanks, by the way i too think LFS understeer isnt a "dramatic"
problem but i think also Bandit77 has it's own reason.
Still i dont feel it like a huge problem, just something a little bit "exaggerated" by LFS physics model and that only on tarmac... but who i am to judge tarmac racing? Everybody know only sissies drive on tarmac real man drive on gravel (joking :D)

[Shotglass]

Choosing the right inertial frame of reference can make the sun orbit the earth. Do you think that is a fact? Or just a misinterpretation?

neither ... dont mistake modeling something for figuring out how the "machine" behind it really works

[March Hare]

Yes, and I want to know how the machine really works.

The reason I'm continuously fighting myself to not dismantle my DFP and see what makes it tick.

[Linsen]

I just gave the XFG a little spin around bl1 with bob's road going setup and an open dif. I tried to drive it pretty much like I drive my real car around a track (a 169 hp fwd with no dif) and I must say everything seems to behave pretty much as expected. Not too much wheel spin on the unloaded front tyre, tbh. Of course I modulated the throttle on corner exit a lot more than I normally do when racing in LFS, but that's what I do irl, too, slightly lift off when I get a hint of understeer/slipping front tyre. If the power band of the XFG is anywhere close to that in my rl car, I actually doubt that I would get much less wheel spin with it, even considering that it has more power (I mean, I never got below 4k rpm with the XFG, mostly above 5k, actually).

I'd have to to further rl-testing to absolutely sure, but for now I'd say LFS is pretty close to rl, at least not dramatically far off.

edit: don't mind the crappy line through some of the corners, I wasn't really trying. ;)