Braking distance realism

New player here. Curious what other people might have as far as opinions on how realistic the handling and braking are for the on road cars (I haven't played with the off road vehicles or trucks yet). I found it rather silly that some cars appear to accelerate as fast as they slow down. No real car is like that. I've driven a lot of actual cars on the autobahn in Germany, and I know what it's like to go 140+ mph (220+kph). I also know what it's like to hit the brakes at speed as well, through my own testing and through one near mishap where I had to ride the ABS from 200 kph down to about 80 kph.

Doesn't matter the car I picked; the braking distances in the games are silly long and you have no control over the car even if it supposedly simulates ABS and ESC. A modern car with ABS/ESC and good tires stops what seems to be impossibly fast. Even on my pretty old "real life" BMW, I've tested the braking distance so I know what it will actually do if I need to stop, and you have so much control riding the ABS even down from 100 mph on an ice road in the Scandinavian arctic.

It seems like there should be a way of quantifying the braking distance in game to see how it compares to real life values in comparable cars. Nowadays, even crappy sedans stop in about 110 feet (~30 meters) from 60 mph to 0. I'm wondering if anyone has ever compared what the game simulates to what happens in real life.

I'm rather disappointed with the driving physics, even with pedals and a force feedback steering wheel.

Crash physics are really fun, as are the maps. However, the driving physics leave much to be desired.

 

From my own tests on pure Grid map and the starting grid stretch of the WCUSA racetrack, I'd generalise that braking distances were 5-10% longer than expected. Definitely better than older versions of Beam, but still some way to go. Barring the sticky stretch at the drag strip, I'm not aware of a more optimal surface in game.

The tested vehicles were the 2WD versions of the modern ETK TT sports and the turbo AWD versions of the Sunburst and SBR.

The brake preheat option was on and the airspeed and cruise control apps were used to ensure the stops were from an indicated air speed of 100 kph. The ground speed and cruise control apps read 99.

(Hypothesis below)

Spoiler

I think that it's partly due to the tires and insufficient aero resistance. The tires still seem to suffer from the peaks of sudden increased rolling resistance/instability at specific speed ranges (depending on the specific tire and car weight / vertical load) so aero drag is set lower to compensate. This results in cars above a certain power having vastly greater top speeds than lower spec versions even with the same tires, a key example being the modern ETKs.

This issue was brought up by some but it doesn't seem to have been acknowledged.

 

I don't know if web page exists anymore, but all kind of cool stuff in that saved page (in zip):

Title of attached pdf:
Determination of rolling noise and rollingresistance
coefficients and conduct of wetsurface
brake tests on utility-vehicle tires

There is such papers on passenger tires and on dry surfaces too.

There is lot more, don't have time now, but real world rolling resistance data is possible to get.

 

Don't be sorry, be proud, your ability to interpolate from limited data is very impressive.

We just measure if what you make is close to IRL, you have the hard part of figuring out how to make magic happen

 

Use ABS, and the brake bias is adjusted on the fly.
Thanks the pdf is informative.
BTW, modern street-legal sports tire can do up to 1.2g cornering/decelerations.

 

While ABS does prevent wheel from locking, is it really adjusting brake balance before wheels lock? I think that brake bias adjustment still has meaning, not sure if for minimum stopping distance, but when driven hard, it does affect how car turns in when I start braking or then my memory is telling me nonsense, which is highly possible too.

GT3RS with street legal tires does more than 1.2g I believe? Depends from speed too I guess as aerodynamics starts helping from relatively low speeds.


I can see 40 meters or bit more and that would be at least 10% more when compared to numbers Diamondback posted, neutral or D had not effect, imo:

That is 1g slowdown at best part and over 0.9g all the time if I don't see it wrong.
To stop that vehicle in 32 or 33 meters g-forces would need to be higher, close to that 1.2g then? Those are not all sports either.

ABS seems to make stopping distance about 7 meters shorter than locked wheels from about 100kph speed.

Is that then huge braking distance when it's some 5-7 meters longer from 100kph than data from IRL seems to indicate?
From higher speeds brake heat/fade can be increasing braking distances.

Also ABS can get confused and is not allowing to brake under some conditions.


One odd thing is that drag slicks are better stopping a car than off-road tires on grass, I think thread depth thing was made to cure such from happening, but it is happening.


It was over 400 meters that ABS and studless winter tires took to stop car from 80kph at 2005 on smooth ice. Autobild magazine did winter tire test 2004/2005 I think, used to have scan of test, but could not find that. Without ABS stopping distance was under 100 meters I think, can't remember for sure, but it was roughly there, ABS gets terrible bad on smooth ice with weak mechanical grip, unless they have improved that in last 14 years, but it is difficult problem with ABS.

 

Hidden in spoiler because my reply is rather long and not really related to the OP's topic.

Spoiler

It's still odd to see a 330+ peak BHP station wagon easily eclipsing 300 kph while a 180+ peak BHP version struggles to even reach 230, even with the same bodywork, wheels, and tires fitted. (Just tested this in the background using cruise set at 400 on one and the right trigger locked for the other. Only difference was the engine.)

The main point here is that there are still odd instabilities in the wheels and/or tires, maybe even the suspension hub structures, that result in artificial ceilings at certain high speeds that require a disproportionate amount of power to overcome. This issue also causes the car to weave a little at certain speeds as though the steering was twitched.

Realistically, no doubt it's impossible to find out the 100% exact, de-restricted, drag-limited top speeds of vehicles, and it's hard to decide how long to wait at full throttle before deciding that there's negligible acceleration and recording the speed. Both cases assuming the rev-limiter isn't met, and impossible real life conditions like consistent wind free testing conditions, no other vehicle instabilities, etc.

To my understanding, the former would be the exact point in a power-velocity graph where the car's WHP curve meets the curve of friction power from air and rolling resistance. Now in theory, would one have to essentially wait an infinite amount of time for precisely zero acceleration? ...and I'm getting carried away.

While there are occasional changelog remarks about fine tuning aerodynamic drag due to reductions in rolling resistance, I believe this resonance issue was last mentioned around the introduction of V-beams a few years ago, maybe also when the tire tester was shown off?

It would be cool if the issue was looked into during the current research into tire thermals and other improvements. Though I'd admit there are probably other pressing issues in getting the game to Beta.

After the odd resonance/instabilities are tackled/further minimised, I'd try to proportion top speeds to those estimated in some formulas/calculators available online.

When calibrated to a 180+ BHP station wagon reaching 235, the 330+ BHP model, taking both models' plateau like torque curve into account (same gearing and tires) and assuming no difference between stated BHP and actual WHP due to manufacturer sandbagging, tops out around 280, not above 300.

It still might not be 100% accurate to real life, but the end result will be superior to pretty much every other road car driving simulator.

Doesn't look like brake fade is an issue for the modern ETKs in these 100-0 tests (at the moment) even when repeating in rapid succession.
The other post-millennium cars with sporty brakes and sport or semi-race pads seem quite fade resistant too.
Only the hard braking after the long straight in WCUSA's race track seems to faze them.

Suggest trying the higher end K/800-Series models with sport R18s and R19s as a baseline, then fitting them with base brakes and base/premium pads and repeating the test. It's fun to then compare the results with the 80's stuff with ABS.

 

Brake fade might play part at 200-0 tests or similar.

Attached is real world data of Ferodo DS2500 brake pads, which are something of bit sportier side than regular ones. Can't remember which page or pdf I found that as it was really really long time ago, more than 10 years ago I would think, despite file claims 2012, but that is just date of one HDD crash.

Anyway that is interesting bit of information as such consequent brake tests data are not always found.

There is really lot of pdf documents on my disk, scientific papers, but my brain is too mushy to really get it all anymore, I used to know that stuff, but today it's just nothing.

Anyway, testing against real world data can be indeed interesting if I just would have more time for the stuff.


@Diamondback, yeah, might do some test later, I don't really have any opinion in either direction, but finding numbers and seeing what comes out of test is usually quite interesting, so might do some more testing out of curiosity later.

Standard tires of 80's are different of 90's and modern tires are just quite different, as more silica compounds have been added tires have become quite bit better alone from that.
--- Post updated ---
I was thinking that steering input during the braking might affect braking distance, as I was using gamepad it was nearly impossible to not have tiny amount of steering input during braking as same analog control brakes and steers in my config.

So, I set up brake to button and used cruise control app to keep steady speed, that way my braking is perfectly consistent.

Cruise control says 100 and brake test says 99, 39.37 meters with base model and Blue ETK800 856t(A) model got 35.88 meters.

Perhaps I should set Cruise control to 101 to get proper 100-0

856t has Sport tires, were those kind of like semi-slicks or were racing tires like semi-slicks? Can't remember, but should sport tires and 856t be compared to sporty car klasse already?

If we consider 33 meters to be representative of the segment, then 35.88 meters is still 2.88 meters more, however around 3 seconds braking and about million things can cause tiny variation and with such short distances we have situation where tiny change causes small increase in distance that is several percent.

Brake testing with base model of ETK800 from 200kph to 0 gave me result of 159.64 meters and I don't think there was any brake fade effect really. 159.64 / 4 = 39.91 so I don't know if there really is anything wrong with it other than it stops bit slow.

856t with sport tires stops bit better, but it still is bit slow to stop, difference between base model and 856t for me appears to be believable.

So who has data about normal cars braking from 200kph to 0? Accelerating them to that speed takes bit longer than most places have flat straight areas and when you add safety zones I doubt there are many places where reporters could do such testing? Sportier cars can do such test, but normal cars not so much I guess. Similar issues with top speed testing.
--- Post updated ---
Some numbers, all with ABS
41.65m ETKi 3000i (A) 1429kg
40.23m with kc5 wheels and tires from ETK800 856t ttsport model
36.84m + sport brakes and semi-race pads

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39.37m ETK800 854t(A) 1538kg
38.5m TTsport brakes with semi-race pads

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34.5m ETK800 856t ttSport (A) 1607kg (this has pre-warmed semi-race pads, not really comparable setup to brake test results posted earlier)

It is worth noting that 0.01s difference in braking time and 0.5m difference in braking distance happens, despite having button to brake and Cruise control to accelerate to speed, there is some variation, which I guess happens IRL too.

Also I found out that getting brakes to 500C might not be possible with 80-30kph braking, at least not with braking 9 times only. With semi-race pads I did see 430C with really many stops, but not 500C, of course vehicle weight, ambient temp etc. can make a difference, brake disc type, size, brake pressure etc. just a lot of variables.


If driving physics or tires would be bad, then how this is possible? Sure there can be things that are bit off, but for actual driving I think it is pretty incredible good.


Funny thing is, blowing up rear tires hasn't got much effect on stopping distance or acceleration of this 520hp AWD Bolide

--- Post updated ---
Ford Fairlane 500 test from Car Life magazine, March 1965:


22 ft./sec./sec. translates to 0.68g but Bluebuck or Barstow gets close to 1g braking and even with locked wheels more than 0.7g is achieved. Not sure if G-meter is bugged or what, but seems quite bit high, haven't plugged wheel in to check braking distances as braking well with gamepad is bit impossible, but that surely looks bit odd, just to opposite direction of what OP has trouble with.

Source for borrowed text is attached for amusement, we so live in wrong time...

 

I did check app numbers first with my brake testing static object and it was matching pretty well to base model, not sure about higher end models.

I'm running locked 118fps and HW accelerated UI, if that has any effect on anything, problem is of course that UI is really not FPS stable, at times it falls to some lower fps which makes things even more inaccurate.

Need to check wheels.lua as inconsistencies are really bad with brake distance testing.


Btw, 1967 Pontiac GTO RamAir (400cu), super car of it's time, did achieve 0.9g in braking tests (Car Life, October 1967) F70-14 tires.
However 1968 Ford Torino 2dr HT 390 got only 0.65g with F70-14 tires and as mentioned 1965 Ford Fairlane 500 got 0.68g with optional bigger tire size (7.35-14) than standard.
Those are maximum numbers they recorded.


For Torino 390, 6 stops from 80mph to 0 was enough to cause 20% increase in braking distance.

1969 Ford Torino Cobra (428cu) 4105lb / 1862kg with F70x14 tires got 0.78g, but after 3 hard stops from 80mph got 20% brake fade and rear brakes started to lock before fronts.

1969 Ford Mustang Boss 302, 3610lb / 1637kg (F56.4/R43.6%) Wheelrates F115/R148lb, 0.72" ARB, F60-15 tires got 0.93g braking, but 10% fade in performance with 3 stops from 80mph. Sadly no coasting data as times were changing at 1969 and less numbers more impressions and feelings was direction of the world.





Also for 2dr HT 390 Torino total drag was 180lb @ 60mph, from 80mph to 40mph coasting took 45 seconds, test weight was 4150 pounds.
For Barstow I did get 26 seconds for same coasting test, but Barstow is not 4150 pounds, more like 3600 pounds.

At 25 seconds there was 5mph difference between Cobra and 390 Torino in coasting test, 45 pounds weight difference and different tire pressures, 24psi vs 28psi + variability in tests.

Old days they put lot of good data to magazines, sadly no such data from modern ones, but anyone wanting to compare old Americans in game to data have chance as now there is some real world data from the 1960's, they got to moon back then, so probably were better at car testing too
--- Post updated ---
Guys, happiest day, I found place where I got some pdf files really many many years ago, now they have more, LOTS more, if you like from that Fairlane 500 article, go here and look for Car Life magazines, for anyone who likes to read car magazines of old days, these are really golden stuff:
http://wildaboutcarsonline.com/cgi-bin/pub9990391350594.cgi?categoryid=9990391350594

Also from those road tests it should be possible to get much better idea about braking capabilities of old American cars.

Here is some more braking data from American Supercars of 1965:

20 = 0.62g
26 = 0.81g
Those are maximum values achieved

 

you could ask fufsgfen or diamondback "coke or pepsi" and they'd give you three youtube videos, fifteen paragraphs of reasoning, three paragraphs of data, and five different spreadsheets

 

Yes, confusion must prevail as even air is more agile when confused

Brake point was at edge of glowy thing at left, 353 engine Bluebuck with basic brake pads and ETK800 854t(A)


Then how bad American cars really could be, 1966 Pontiac VIP got 15 ft./sec./sec. which probably is something like 0.47g as maximum for 1st emergency braking from 80mph. I'm tempted to test if that kind of slowing could be achieved by using handbrake alone.


Car Life January 1966, you can get it from link posted earlier.

But that is bit puzzling, so they had issue with one wheel locking up and brakes fading badly, then their stopping time was almost double what Bluebuck stops, so how this works out, tire grip so weak or brakes just heating up so much that randomly one of the rears lock as more pressure is applied.
Car had power assisted drum brakes.

That was like really bad.

There was other article about one of the first cars from Detroit that had decent brakes (was Mustang first?), October 1965 Dodge Dart with discs.
Car had also then new Radial tires, slowdown was 25ft./sec./sec which according to convert.exe comes to ~0.78g with drums such slowdowns rarely did happen, afaik.
This one did not have power assisted brakes, but discs at front and they praise brakes a lot.

Also in January 1966 issue there was Ford Galaxie 7-litre, they mention lot of numbers there.
Slowdown was between 27-29 ft./sec./sec. which they mention being 0.8 G
That is odd because I get 0.8391-0.9013g, I'm not sure why there is such difference, could it be just reporters being reporters or is conversion I get from tool slightly off?

They mention only Corvette Stingray being better in their testing.
Vast majority of cars from Detroit they mention being 18-21 ft./sec./sec. 0.5-0.6G which I get to be 0.56-0.65g
They did complain that power assists of Galaxie being too strong and they got rear wheels lock up too easily.
Back then load compensation valves might of not been yet part of brake systems.

Bluebuck can reach 0.9g as max and 0.85-0.9g is typical range, that is with 80% brake pressure setting and flooring the brake fully so no lockup occurs, with better brake control it might do even better.
Bluebuck had basic brake pads, drum brakes and default BiasPly tires, so against data from Car Life magazine it looks like to be way too good at stopping.

Is it brakes or tires issue then, that is unknown, 0.65g or so was what I saw with cornering.
Considering also that ETKi 3000i can spin rear tires in burnout really easily (with 9% throttle), it would be quite wrong to claim that tires have too much longitudinal grip, different tires might have different imperfections, but would it be more of brake issue.

I did notice there was something around 1300N brake force at front brakes with Bluebuck, tires were not locking and that over 1800kg did stop in relatively short distance.

Braking is pretty good, but more I test, more it looks like there is need for some evaluation with braking performance.

Still modern ones are not getting huge braking distances, it is pretty close to IRL as long as ABS is not malfunctioning.

 

This is difference between Cement mixer and ETK800 in stopping distance from about 100kph:


Then here is 76 metric tons stopping from 80kph in 49 meters and on dusty pavement, you might want to watch this twice:


Here is few more:
1. 21 metric tons (empty trailers) stopping in 45 meters from 80kph
2. same as 1st video from another angle
3. relatively modern Armored vehicle stopping from 86kph in 50 meters
4. Early 2000 dump truck with trailer, 60 metric tons, stopping distance from 80kph is 87 meters, disc brakes at front axle, other brakes are drums
5. Tanker for transporting dangerous stuff (fuel, oil etc.) 60 metric tons, stopping from 80kph in 46 meters:


You can see how much modern brakes are better than older ones, also how insane stopping power there is even with locked wheels when there is more mass.


~13.5 metric ton Cement mixer with all drum 80's brakes (+abs) stops in 35.48 meters from 80kph it seems.


~25 metric ton truck and trailer stopping from 81kph at 34.97 meters

So it is possible to stop loaded trailer + semi faster than many of the modern cars in game.

Here is then relatively modern Volvo SUV stopping from 80kph in 24 meters, bit over 1g, same test day those crazy finns did testing of those heavy trucks:


SBR4 AWD TT S2 stopping from 80kph in 22.65 meters:


Yellowish ETK800 was going 80kph 27.4m and red one was going 100kph, also added Bluebuck there for a good measure, ~30.9m, I did count squares to place it, place got bit crowded



Then there was this Bus (relatively modern, much better at stopping than bus in BeamNG) test, stopping from 40kph in 6 meters, from 50kph it stopped in 13 meters.


Same bus from 100kph stops in 39 meters, ~0.64g (that is faster stopping than ETK800 base model):


This might be some interest too, stopping from 80kph, Skoda Octavia 2009 in 22.5 meters (definitely not the sporty variant of that) and Porsche Cayman 2013 in 19.5 meters:


Semi stops perhaps bit quick, so does Bluebuck, ETK800 is bit slow to stop in lower trim levels, SBR4 TT S2 seems to be stopping bit slow, so does top level ETK800 models too I think, but see videos and get entertained or something.

At least there is now realworld data from some more vehicles in those videos, also we can conclude that finns are bit odd, but they seem to be somewhat useful

Also I think those finns used to have some video of loaded trucks with trailer doing braking tests on ice with and without abs.
--- Post updated ---
Here is winter testing video:


Ford Focus stopped on snow from 70kph in 82 meters (with good studded winter tires)
43 metric ton truck with new tires 133 meters
43 metric ton truck with old tires 217 meters

They did also test double lane changing on more icy surface and did a 'drag race' too.

Also there was this from this in presentation that was done from that testing


This is lateral grip:


Braking distances with ABS from different speeds and different coefficient of frictions


Charts are from PowerPoint presentation that is from here, but there is not really much anything else useful in those I think:
https://nokiantyres.studio.crasman....nts/press_events_archive/2012/truck_test_2012

Seeing some data like this is certainly different from typical pavement race car oriented data.

Also, geeez, this is one long post, but can't be helped, doubt that this kind of stuff is known by too many.

 

Crap! Sorry guys, I thought I replied yesterday but it's not here. So I'll type something again. I've been pretty sick and haven't had a chance to reply before yesterday. I actually interned at BMW's driving simulation department in Munich. It was my job to do vehicle vibration programming for their portable simulator . The force feedback simulation was based on two PhD dissertations lol. It was a remarkable driving experience! The graphics were terrible though The physics were simulated on a cluster of 12 or so high end computers of the time (2009) to maintain 80+fps all the time.

So the general consensus is that the stopping distances are very close to reality. I think that my initial misgivings must be partly due to the loss of depth perception, using a steering wheel and pedals that don't mimic a real car so well, and not getting haptic feedback (vibration and movement of the car). I have about 12 hours in game time now and it took some getting used to. Now it's very entertaining.

I appreciate all the thorough replies. I didn't think I'd actually get any! I'm an engineer by trade, so I actually love numbers I do have to point out that I was pretty close with my 110 feet figure, as that is 33 meters and pretty close to some pretty average sedans today. Even my old VW Jetta from 2003 had a stopping distance relatively close to that with better tires and better pads.

But that aside, I found that all but the most highest level cars (10+) don't behave like they truly have ESC. Even my 20 year old BMW 5 series will steer the car according to the input of the steering wheel, and that's actually not the full ESC hardware/program (BMW's ESC=DSC). It only has ASC+T (automatic stability control plus traction control, not dynamic stability control). Once you apply the brakes, it "steers" with the brakes with proportioning valves for front/back and left/right and doesn't apply the brakes itself, except to reduce spinning from excessive acceleration (it also mimics a LSD with the brakes). Then with ABS, it behaves much like it has DSC (same as ESC). I've driven 170 kph on ice roads in the arctic, and felt confident with the stability control of the car to direct it where I wanted it to be. Even the Jetta with it's very soft suspension, the stability control was it's saving grace; otherwise, it handled surprisingly bad. Once you start sliding, the ESC (ESP on a VW) would steer the car almost magically. I feel that aspect of "on the limit" driving is somehow lost.

In many cars in the game, once you start sliding (even at low speeds, like 50-80 kph), it is almost impossible to correct. However, this is significantly improved with the ultra sporty cars (the 10+ level ones). It's difficult to put into words because generally, I always felt that cars with softer suspension had more forgiving handling characteristics. You don't need twitchy fast reflexes. So it was a surprise that the faster more sporty cars were far easier to drive as they started to slide around.

Interesting discussions above. I'm sorry that I can't reply to everyone.