Braking technique with ABS on?

[Billy Pilgrim]

I'm not that sure on what exactly is the technique to use when using ABS.

I've read up a good bit about braking technique without ABS (trail braking especially) and feel relatively confident that I'm using the right technique with that, more or less. But I do not know what the advice is on braking with ABS.

Any advice?

 

[BrightCandle]

It doesn't really change. ABS just stops you locking up and ideally you don't want to be leaning on ABS at any point as it produces less deacceleration than the right amount of braking. Its not all that well implemented in AC so it tends to just be a straight up assist but largely you can ignore ABS from a braking perspective other than paying attention to when it kicks in and trying to just avoid that from happening.

 

[Neilski]

you don't want to be leaning on ABS at any point as it produces less deacceleration than the right amount of braking

I've heard this said a few times but I'm not sure I've ever seen any tests to show how much difference it makes. Do you know if any have been conducted? In principle it ought to be pretty easy (in fact I may even do some basic ones myself now that I'm thinking about it).

 

[mclarenf1papa]

Where ABS helps is trailbraking; you DO want to be leaning on it there because you'll be able to brake better than you could without it, especially with racing ABS.

 

[Michael Krone]

I dont think AC does ABS or TC properly so I have always learned cars with both off.

I agree with the above statement that AC's ABS provides less deceleration than the proper amount of braking. I have no info to back this up but its one of those things you feel. I could also just be wrong. Wait, no I cant. Im never wrong, just ask my wife...

Seriously tho, what I would like to know is... Does wheel lock up occur at the exact point where ABS would theoretically kick in? Knowing that should should give a definitive answer.

EDIT: So now im thinking about it a little more. Having ABS engaged and active is going to give millisecond intervals of lockup, correct? So braking (idk say) 5 seconds with ABS active and engaged will yield a longer distance traveled vs 5 seconds of perfect braking with ABS off, right?

 

[Mr Deap]

I dont think AC does ABS or TC properly

I have the same impression.
It's either, peeps claim you can't drive & are a troll... or you simply called it bomb diving with the brake & move forward.

 

[Neilski]

To answer the OP's actual question about braking technique: from my limited experience of playing with AC braking settings, my instinct is that even with ABS on, you're still going to gain from feeding the brakes in with a little care rather than simply stamping on the pedal instantly (depending on the suspension time constant), having the brake balance as near correct as possible, and setting the brake force not too far above the point where you'll lock without ABS. But I don't know how much flexibility there is in the AC ABS algorithm - e.g. does it treat supercars or GT3 cars the same as normal road cars? (Modders will doubtless know )

Since I don't have a motion rig, seat belt tighteners, or even a load-cell brake pedal, I have no feel for the brakes and rely heavily on ABS or reducing braking force (if no ABS) to avoid lockups in the main stopping zones. (G27 pedals.)

However, to partially answer your question @Michael Krone, ABS relies on detecting a wee bit of slip and the art is in having enough slip to brake well (slip is never zero if there's torque on the wheel, that's just how rubber works) but not enough to go sailing way past the optimum. So it's not a binary thing where you can just say you've exactly reached the "correct" threshold; it's a judgement call which depends on the characteristics of the rubber and the desired behaviour of the braking system. Lots of cars even in vanilla AC have variable ABS settings in fact, and I *think* this is just adjusting the slip threshold but it may go further.
I'm pretty certain that an ABS-braked front wheel should never entirely stop rotating, until the car is going really slowly (when ABS typically deactivates). With a human controlling the brakes, actual lockups where the wheel truly stops can and will happen.

Personally, I like to think that even just braking in a straight line, a racing ABS will kick the backside of any human because it can be tuned to do basically the same thing as a human but much faster and more accurately. How could it lose? (NB: guesswork alert! )

For sure I'd guess a consumer ABS is likely to trigger at lower slip levels to play it safe and won't maximise deceleration, so maybe human racing drivers will trivially beat those systems.

Good point above by @mclarenf1papa about trailbraking... and this is reason enough not to forego ABS when it's factory-fitted!

So braking (idk say) 5 seconds with ABS active and engaged will yield a longer distance traveled vs 5 seconds of perfect braking with ABS off, right?

If you mean constant perfect braking, then I'm tempted to say "no" because although this might be true in "perfect" conditions where the grip on the road is totally constant, in real world conditions the microscopic variations in the road surface (not to mention the suspension compression varying after you first hit the pedal) will mean that the perfect braking level isn't constant, and so as soon as the tyre goes past the optimum slip for a few milliseconds you have an unstable equilibrium where the increasing slip reduces the grip which increases the slip still further - positive feedback, and you lock up...
If you mean variable perfect braking (controlled by magic ) then yes.

I realise that I don't know if any real-world ABS systems modulate the brake pressure in a continuously variable way, or if they are all just on/off at a high frequency. Am gonna guess that the latter is less close to perfection but much easier to implement and maybe even safer for road cars in terms of failure modes...

 

[Stereo]

Lots of cars even in vanilla AC have variable ABS settings in fact, and I *think* this is just adjusting the slip threshold but it may go further.

Yes, vanilla ABS just stops braking on the wheel (or wheels if it's not 4 channels) when the slip threshold exceeds a certain amount. Since it's able to just know slip rates directly, it doesn't work at all like a real ABS system (which doesn't know slip rates directly, only speeds of the wheels, and will limit braking on any that are moving slower than the rest)

I'd guess most road cars also include steering input & a yaw sensor to decide what to do these days since you can allow a lot more slip if the driver wants to go straight. Race cars definitely do have different ABS modes depending on steering.

 

[TylerPL666]

If you set ABS to ON in settings its always ON even if oryginal car doest have it, and you cant change it.

If you set to off, you will stll have ABS if oryginal car have it and you cant change it.

If you set ABS to Factory it will be ON if oryginal car have it and you can change lvl during race.

Same with TC settings.

Probably you drove a car with ABS in oryginal (real) car so even if you set it to OFF you just block option to adjust the ABS lvl, but it was still working.

Have a nice lockups and spins

 

[mclarenf1papa]

If you set to off, you will stll have ABS if oryginal car have it and you cant change it.

ABS off in AC disables it completely, it doesn't just disable adjustments. ABS set to factory is as per the real car.

 

[Azorath]

ABS is an aid for daily drivers that does not require any driving skills than point and drive.

That seems like an underestimating it but that's the real point of it's creation.

And the technique for it to use it is; when need of immediate stopping just slam the brake until it reaches it's end and try to remember steer from any danger, if any.

For racing it's essential for wet surface, as any amount of braking can send you skating to the barriers.

For the record, I don't think load cells are a requirement but seriously heavy brakes are indeed required for ABS off, I don't own a loadcell but modified my cheap pedals with loads of springs so I can use abs off techniques but I don't prefer to..


Also ABS works very well in AC, just take a good look braking with some app that shows locking state of four wheels.

 

[Billy Pilgrim]

Thanks for the replies. There’s no simple answer, obviously. I suppose the only way to work out what the best technique is is to experiment by using different techniques and checking lap times.

I have the impression that it’s better not to lean on it too heavily but I’m not sure if that impression is just cos I find it more pleasing not to lean on it. Leaning on ABS certainly takes some of the pleasure of driving away, in my opinion, and that’s why I do prefer driving cars in AC without ABS (so GTE over GT3). I used to keep ABS off all the time but then changed to allowing factory ABS settings as I figured that was going to improve lap times (and was probably the choice racing drivers, GT3 at least, would make too).

I’m guessing that ABS in AC is more effective in GT3 than say, 90s DTM, but just don’t know.

So there’s my impressions, suppositions and guesses to add to the discussion.

We need experiments, hard data, from a very consistent (and good) driver driving a variety of cars. I might give it a go and report back.

 

[onearmedbandit46]

For racing it's essential for wet surface, as any amount of braking can send you skating to the barriers.

Essential? And 'any amount' of braking can send you skating to the barriers? Are you sure?

 

[Azorath]

You can play with Motec recordings to see how abs is working and/or does it change from cars to cars or with different settings.

Essential? And 'any amount' of braking can send you skating to the barriers? Are you sure?

Yup, did you ever heard of Hydroplaning?

 

[onearmedbandit46]

Yup, did you ever heard of Hydroplaning?

Certainly have. But I've also watched many car and bike races in the wet (and have raced motorcycles in wet conditions) that don't have ABS and they don't skate off into barriers under 'any amount' of braking, nor even relatively aggressive braking. Wet weather tires stop them from aquaplaning, not ABS...

 

[Ghoults]

Even with abs and a perfect abs there are still moments where the question is whether to brake or not. While with abs you can trail brake effectively that doesn't mean you should trail brake into every corner. A tire produces only certain amount of grip and this grip can be divided into two components. Lateral which is cornering. And longitudinal which is braking and acceleration. When you add braking or acceleration input in a corner some of that lateral grip is taken away by the now required longitudinal grip.

This means that generally in faster corners it is better to not try to trail brake all the way into the apex. Instead try to come off the brakes smoothly and you can carry more speed through the corner. You'll have little bit of lateral grip as a result. This can make the car feel little less stable and it can feel really off-putting initially. I think this feeling is partly due to how the car becomes more agile after the brakes are released (not just when the brakes are released but also after that) which is easy to misinterpret as the car becoming loose. After all, dragging the brakes makes the car feel more stable but this is understeer. So when you come off the brakes you suddenly have more turning capability.

Best corners where to to try to do little less trail braking are obviously the fast corners like parabolica in monza. Generally any corner that is 4th gear or above in gt3 where you need to brake. Longer corners and camber also allow for less trail braking. Camber increases grip so you can take tighter line whereas in longer corner there is more focus on not slowing down too much.

I'd say dragging brakes is less of an issue if you have load sensitive pedals tho. A spring based potentiometer pedal is usually rather soft so it is easy to even accidentally add 5% braking input. With loadcells and hydraulics it takes more effort to get that 5% so you are less likely to do it subconsciously. Excessively trail braking is a bad habit that is harder to learn on load sensitive pedals.

Other thing abs can hide is that it is easy to accidentally turn a little bit as you brake. Even with abs on it is still better to initially straighten out your braking zones. Take the turn 1 at nurburgring gp. I always make a mental note to brake straight in that corner because it allows you to brake tiny bit later. I see a lot of people who keep steering a little bit as they brake there. The road does turn to right a little bit there. But if you choose your line correctly you can brake straight. You still want to trail brake into the corner but you don't want to trail brake all the way through.

That little bit of turning while braking does not just lengthen your braking zone but also wears out and raises temps on your front tires unevenly which can become a factor in longer races. If you drive any non-abs car you may suffer a lot of inside wheel locking into turns if you learn to brake with abs and learn to turn little bit as you brake. This is another bad habit that can bite you later when you move from abs cars to non-abs cars.

I am not suggesting you to start coasting in corners corners. Coasting is something you do where you are way below the tires' grip potential. So when I say don't try to trail brake into every corner I don't mean you should coast. You should still maximise your tires. You should always be braking, accelerating and/or turning as hard as you can.

Last point (!) I am going to make is that make sure your pedals and brakes are correctly set up. If you drive a lot of modded cars that have abs it is possible the car's braking values are not set correctly. Because abs literally prevents the brakes from locking it is possible the mod maker has set the brake power too high. After all what the abs does is limit braking power once you demand too much grip from the tires. Typically this could be in straight line braking somethng like 70-80% of your maximum braking effort. So without abs this is where your threshold braking would be. This is where your abs starts kicking in. In abs car you can go directly to 100% maximum pedal effort and abs basically reduces that pedal effort to that 70-80% which is the tire slip maximum for that abs setting.

However if the brake power is set wrong that abs bite point can be as low as 50-60%. You can still brake in straight line as abs prevents you from locking up but once you start coming off the brakes and you start trail braking you may be only at 60% pedal effort and you think you have released the brakes slightly but you are still actually braking at 100%! You haven't actually come off the brakes at all.

To check for this take a car you know well. Turn off abs and just try to brake straight at the limit. Pay attention to how much pedal effort that takes. Then switch to the new car and do the same. If the pedal effort feels very different then you can try reducing brake pressure in car setup if the brakes are overly sensitive. If the brakes feel super weak (rare) you can also short calibrate your brake pedal (use partial travel with pot brakes, calibrate to smaller max force with load sens pedal) to get that threshold where you want it. Or you can just leave it as is and treat it as a car specific feature. Maybe that car has more sensitive brakes or less. But be aware of it because it can be hard to detect when driving and can cause understeer on corner entry that may feel like setup issue.

 

[Neilski]

you may be only at 60% pedal effort and you think you have released the brakes slightly but you are still actually braking at 100%!

This is a good point. However, it's not instantly obvious how much difference it would truly make in an ABS-equipped car because of course as the lateral grip required for turning starts to rob the tyre of longitudinal grip, the ABS will automagically decrease the average brake force still further to keep the wheels turning. So... yes, it feels likely to be at least somewhat harmful, but how much?

 

[Lizard Of Bodom]

I think its hard to compare real life ABS to game ABS and also differentiate between your road car ABS and real life racing ABS so there is a lot of variables here. I also lean towards the "good driver without ABS will brake earlier than push-pedal-to-floor-and-wait" but its variables like tyres/surface/condition etc makes difference here aswell. In some cases ABS will also go "stupid" so try stopping earlier on ice with ABS on for example...

As for AC itself - I have set the fanatec wheel display to show "abs" when its activated in game, and it does help a lot, I dont have haptic feedback on pedals so this allw me to be on the verge of ABS engaging and I do feel it helped me to improve my times (road cars).

 

[papagiuseppe1]

I think its hard to compare real life ABS to game ABS and also differentiate between your road car ABS and real life racing ABS so there is a lot of variables here. I also lean towards the "good driver without ABS will brake earlier than push-pedal-to-floor-and-wait" but its variables like tyres/surface/condition etc makes difference here aswell. In some cases ABS will also go "stupid" so try stopping earlier on ice with ABS on for example...

As for AC itself - I have set the fanatec wheel display to show "abs" when its activated in game, and it does help a lot, I dont have haptic feedback on pedals so this allw me to be on the verge of ABS engaging and I do feel it helped me to improve my times (road cars).

the very limited feedback is the main problem driving without abs, ive locked up in an old car a couple times and there's a very distinct feeling through the pedal and steering column also the whole car shudders, but in acc it's barely noticeable until too late.