Brake Bias and Engine Braking

[martine_wedlake]

Just a quick question for those fast drivers out there. I've noticed that many (most? All?) of the really ast setups have a brake bias set quite a bit more forward than I'd expect. Seems like I've read somewhere that people are doing this because they're using the engine to slow themselves down.

Why? I've read from Carroll Smith that you want to set the car up for maximum braking with just the brakes (I'm sure Carroll has some pithy comment about brakes are for stopping and engines are for going; but I digress).

So can someone explain why engine braking is so popular?

[Blackout]

Im not that fast but I'll try to answer anyway. Both are used at the same time offcourse, the brakes, and the engine to help a litle its used in real life too I think but you really cant brake only using that. And in LFS in its current state its better to brake early (thats why low brake power and front bias) on the straight and have max speed in corner, its very hard to brake late allmost in the corner itself, and front brake bias is more safe. Engine braking is effective way to help you slow down, and the damage isnt that good yet and it doesnt affect in short races. Using engine braking and having front brake bias just doesnt have anything to do with eachother, or atleast I cant see any connection.

[XCNuse]

er.. i try to never engine brake, because it spins the rear wheels and then you screw yourself (ei: test it out with the FOX)

i dont see many 'high' brake biases.. most around low 60's to mide 70's

[filur]

FOX without engine braking?

I know a whole bunch of corners i slow down for / thru by exclusively engine braking.

[SkyNet]

er.. i try to never engine brake, because it spins the rear wheels and then you screw yourself (ei: test it out with the FOX)

i dont see many 'high' brake biases.. most around low 60's to mide 70's

Well, most setups i've seen are using mid 66 to 69 (fox). Not so sure about low brake power, i normaly use 590nm to 630 max, but lot of other players use 650 and above. If i use the same i lockup. Must be my driving style :shrug:

[Hoellsen]

i try to never engine brake, because it spins the rear wheels and then you screw yourself (ei: test it out with the FOX)

No. Engine braking does not spin the wheels. Downshifting at the wrong revs locks the wheels for a very short moment which might get your rear lose.

[Blackout]

Most hotlap sets have low braking force, due the lines WR guys use. I allways use much higher force in races. Mostly because if you really have to stop quicker because something happening front of you, you can. You feel safer :D

edit. And yes, if you lock your wheel you have shifted down too early, its more easier to lock with cars with high revs I think...atleast for me it is :P

[Goop]

Much like Blackout, I like to keep some braking power in reserve. If I miss a marker, or something happens in front that I wasn't ready for, I can downshift fast, not blip the engine too much, and just ride the throttle a touch to keep it straight.

Also, if you're not going to be able to pull it up, you can steer it quite a bit by locking the rears a little with a downshift. I think it's something that probably comes naturally with a bit of time at the wheel, learning to chuck it around a bit.

[Vain]

Also, if you're not going to be able to pull it up, you can steer it quite a bit by locking the rears a little with a downshift.I do that quite often. Either using the gearbox or a bit of additional braking at corner entry. 15% of the time this leads to a nice drift (which looks strange in the FOX...) but it sure is fun. :thumb:

Vain

[danowat]

Depends what car you are in, there are cars that benifits from engine braking, XFR/UFR, and those that don't FXO springs to mind.

Dan,

[colcob]

I sometimes use some extra engine braking on the last shift just before the corner to loosen the car a bit on turn in and get it rotating nicely.

Can go wrong though if you shift a bit early :)

[nikimere]

it's simple, why use one method of slowing the car down when you could use 2? you stop faster.

[Greboth]

I agree 2 braking methods are better than 1 and i find that fine in the FWD cars. It can mean the front lock but a bit of a press on the accel n a little lift on brake usually sort it out. I can engine brake a bit in the rwd street cars. But the SS and GTR cars i dont engine brake as i found i locked the rears and spin.
As to answer the question in post #1 - its popular as you can brake later and still make the corners.

[colcob]

it's simple, why use one method of slowing the car down when you could use 2? you stop faster.

Well, only if one method isnt powerful enough to lock the wheels. Which is rarely the case in LFS cars seeing as we can adjust the brake pressure up to the max.

[Fetzo]

imho trailbraking is easier with the brake bias more to the front. the rear is way more stable.

if i have to brake hard after a fast straight, i can use the engine to slow down quicker.

[tinvek]

in the end its all down to personal preference

it gives you options, especially in a rwd car, to alter line whilst entering a corner. personally i find i can use a setup which is more prone to uindersteer, then i can balance it on entry with engine braking and with the throttle on the exit, both of which allow me to alter line quite a bit if theres a car in way without loosing control

[Bob Smith]

It's especially useful on cars with downforce, as you can use engine braking to provide more braking effort at high speed when there is more grip, and use less brake strength to help reduce lockups at low speed.

[Chaos]

well I use engine braking as a way to modulate the braking distance, you almost can't hit the brake point exactly the same on every lap, so when i miss the brake point slightly, i downshift quickly, whereas with going early on the brakes, i downshift more relaxed...

[Theafro]

There are two schools of thought about engine braking,

a, set the brake bias (driven wheels low) so that you can use massive amounts of engine braking to assist the wheel brakes.

b, set the brake to work at maximum capacity and use heel & toe (or auto blip) to save loading up the tyres even more when downchanging

I mainly use B with a little spare grip incase i make a proper mess of the downchange.

It's a lot easier to rely on engine braking to slow you down but it means that you have much less control over whats going on at the wheels. and as fetzo says, trailbraking is a little more controlled with more front bias.


Although it makes a huge difference weather the car is RWD, FWD or AWD

with AWD+FWD you can get away with a lot more engine braking than you would in a RWD car, my suggestion is to turn auto blip on (or learn to heel & toe) if you want maximum possible braking effort since the braking force the engine generates varies a lot with revs/gears etc and wheel braking it totally consistant, allowing you to use a hard, consistant braking effort

[martine_wedlake]

I'm definitely in camp B. I just can't get used to a car with too much forward bias. I pretty much always have to dial it back to around 62% or I'll go understeering off at the first corner. I just find it gives me that initial bite to get the car rotated.

BTW: I found my reference to Carroll Smith. It's in Driving to Win on page 2 - 25. He's got a section in there about rowing through the gears vs skipping (kinda tangental), but he does say that we should "Concentrate your efforts on braking efficiently and, when the car has slowed sufficiently, downshift into the required gear (taking care to properly synch the revs) - and get on with the job." I remember, but can't locate off hand, that he also describes a little experiment where you take the car and do some 60 mph to 0 stops; both with and without downshifting. His claim is that by concentrating on modulating the brakes, you'll stop in less distance if you don't row the gears.

[Primoz]

In the FXR i just throw the gears down madly :D So yes, i do use A LOT of engine braking. But hey, it's AWD so it's almost as stable as a rock.

[nikimere]

His claim is that by concentrating on modulating the brakes, you'll stop in less distance if you don't row the gears.
to me that doesn't make sense. why not concentrate on braking like he says but also use the added stopping method of engine braking? :shrug:
no racing driver in their right mind would just brake into a corner and then select the right gear before the apex or before you go on the power.

[Breizh]

In LFS you only have to press a button each time the revs sound right, with some adaptation to the tire's grip, which you can also tell by ear.
Engine braking in addition to regular braking uses even less brain overhead when you're in a familiar car/track situation.

[NotAnIllusion]

The way I enter a corner with for example the XFG is by braking hard at first and shifting to the required gear as fast as possible without locking the fronts while blipping hard, and then in the final gear for the corner I trail brake a little into it and accelerate immediately when I know I won't understeer off the track.

When setting up brake bias I usually aim to have it so that I can trail brake into the tightest corner of that track and the power as high as possible without constantly locking or the rear stepping out too much.

I use engine braking to slow the car down a little more than by only using brakes, and to prevent wheel locking.

[Vain]

to me that doesn't make sense. why not concentrate on braking like he says but also use the added stopping method of engine braking? :shrug: Because one method screws up your brake-balance and brakes inconsistantly and the other can brake very fluently with a well defined brake-balance.

Vain

[sinbad]

Because one method screws up your brake-balance and brakes inconsistantly and the other can brake very fluently with a well defined brake-balance.

Vain

So ignore the gears so that you can concentrate on braking. What happens then once you have stopped braking? Ignore the gears and concentrate on the steering? :)
Most advanced driving teachers, and racing schools, will advise you to be in the appropriate gear for the upcoming corner as soon as possible, which means engaging it whilst braking hard.

[axus]

Also, if you are really really pro, you could adjust the amount of blip you to the slope to change your brake balance, but that is more of an instinct - you can't really learn to do it right because you have to be too accurate.

[Vain]

@sinbad:
There is a difference between shifting down so your average rpm is about 10 000 rpms and putting yourself into the right gear for the next corner.
You always shift through the gears, the matter is just to which time you shift. Either shift down at the red line for additional engine braking or shift down where necessary to get the right gear for the turn and brake using your brake-pedal.

Vain

[tristancliffe]

Caroll Smith's thoughts are to do with improving a driver. He says that most people can't heel and toe/blip very well, and concentrate too much on it. His test is to show how concentrating on one thing (using the brakes alone) is more effective that trying to do two things less well. There's no doubt that in real life, in LFS and in Mr Smiths head that using engine braking with normal braking is quicker, but in real life most people don't actually left foot brake, and hell and toeing perfectly everytime on the limit under pressure is very very hard.

In LFS it's much easier to do both, because we have no forces acting on our bodies, less noise and vibration, less risk of pain, and no risk of wiping out a car or a competitor that will end up costing real money.

[Ball Bearing Turbo]

I find that staying on the throttle for a breif instant while clutching to gear down works fine, my right foot can slipoff the accelerator and land on the brake, so for single gear-down situations like many turns I don't have to heel toe, and don't have to worry about RWD cars getting all haywire on me.

[skiingman]

it's simple, why use one method of slowing the car down when you could use 2? you stop faster.
It makes absolutely no difference whether or not you use engine braking in a game that doesn't involve weak brakes or brakes that overheat and fade. Since brake force in LFS is always sufficient to lock the wheels if you so desire, there is no excuse for the above rather wrong comment.

As Carroll Smith correctly noted, using engine braking as a matter of course makes things less repeatable and less consistent.


There's no doubt that in real life, in LFS and in Mr Smiths head that using engine braking with normal braking is quicker,

Perhaps in cars with downforce where optimum brake balance changes with airspeed...other than that, why could using both be "quicker"?

[tristancliffe]

Because you can use the engine braking as an extra source of braking. If you're not threshold braking with every wheel you're not braking at full capacity (assuming a straight line), and it's highly unlikely that you'll ever get the master and slave cylinder sizes, bad sizes, effective disc diameter and brake bias perfect for every corner on every track. Thus if you use engine braking you can reduce the pedal braking on the driven wheels and use the extra (and free) engine braking to boost the resulting loss of braking on the driven wheels. Thus you have more perfect braking more of the time.

The downside is that it would take rather more driver skill to make use of this than not, so it's not widely done. And it's not done much on light cars (say single seaters) as they become very twitchy under braking, with or without downforce.

At least that's my understanding.

[Vain]

Engine braking can be used to adjust brake bias dynamically, but when you want to brake in a straight line, you could just set your brakes for this matter and brake with perfect bias and perfect strenght.
With turning this gets more complicated. While trailbraking it is desirable to have a higher front bias, or you'll lock the rear wheels. Thus it might be worth trying to use the engine in an RWD car to move brake bias back while braking in a straight line and having the more front-biased conventional brakes on while trailbraking.
But the maximum decelaration allowed by the tyres can be achieved both ways. With or without engine braking. It's a matter of preferance and setup.

Vain

[A M R]

i usually brake hard at the last moment and then trailbrake while engine braking to minimise locking the rear wheels (with auto blip on).

this works a treat and i can outbrake quite a few people = faster times...

[nikimere]

It makes absolutely no difference whether or not you use engine braking in a game that doesn't involve weak brakes or brakes that overheat and fade. Since brake force in LFS is always sufficient to lock the wheels if you so desire, there is no excuse for the above rather wrong comment.

As Carroll Smith correctly noted, using engine braking as a matter of course makes things less repeatable and less consistent.


Perhaps in cars with downforce where optimum brake balance changes with airspeed...other than that, why could using both be "quicker"?
Why are you trying to complicate things? The simple answer to which is quicker is... A combination of both engine braking and normal braking together is the fastest way to slow down your car, be it IRL or in a game.

[skiingman]

Why are you trying to complicate things? The simple answer to which is quicker is... A combination of both engine braking and normal braking together is the fastest way to slow down your car, be it IRL or in a game.

:shrug:

I dunno. Not just Smith, but very good drivers I trust have suggested making downshifts as late as practicable, unless one has a very good reason to need the extra engine braking. I think the true benefits for experienced drivers were best described by Vain and Tristan.

One of the things I see as an obvious problem is feel. A good braking/steering system gives a lot of feel for what is going on at the front corners of the car. In my experience, the feel as to the braking at the rear is more vague because it isn't as dominant and isn't hooked up to the steeering. With engine braking, you need to be a left foot braker in order to modulate both brakes and engine braking at the same time. I think the benefits of engine braking show up in situations like tristan describes, because you cannot adjust brake bias for every corner perfectly, but can do a much better job if you can modulate engine braking to modulate the effective brake bias.

This is not something that is easily done. Its stupid/pointless/impossible on the streetable cars I race that have synchromesh gearboxes. For them, the benefit of engine braking is saving the inevitably undersized brakes from abuse.

In LFS, it seems to me that since the feel of braking is lacking compared to the real thing, you have to rely on either lots of practice or secondary clues to know when you overdo the engine braking and cause understeer/oversteer depending on drive configuration. Since there is always plenty of brakeforce in LFS, aggressive use of engine braking seems to me to uneccessarily complicate things at the expense of consistency.

However, for people looking to run WR times, the ability to dynamically adjust brake bias without twisting a knob/punching F12 has obvious benefits. I wonder how large they are. I imagine the benefits are greater on the cars with downforce because their apparent mass distribution changes with airspeed. Reason number 13516 it would be nicer for everyone if racecars had the wings loading the uprights instead of the chassis.

[jamesrowe]

A mixture of engine and brakes for braking is best for me. but be careful not to shift down a gear to many at high speeds, it ruins your engine as you lot know no doubt

[Michael Denham]

A perfect example of using engine braking to help turn in is in the hairpins on AS North using Race_S setup on the FZ50. I was used to trail braking into those turns in 2nd gear, then I realised 1st gear was long enough, so I started using 1st, and boy did it turn in a lot better :) Then for other corners where the back is already feeling a bit loose, I'll turn in on the brakes in a higher gear, to keep from getting sideways. So, it's nice to have a variable brake bias for different corners on the track... I know this has already been discussed, but I thought I'd bring up this example of it :)

[JeffR]

It depends on the car. In real life, many racing cars have their clutches setup to limit the amount of engine braking, probably for two reasons: 1. to keep the rear tires from sliding; 2. to keep the engine from over-revving.

The other issue is that the amount of engine braking depends on what gear you're in and the engine rpms. It isn't consistent. However, I have a tendency to brake a bit early and modulate the throttle while approaching the apex of a corner, but for slow speed turns, I'll sometimes leave the car in 2nd gear until past the apex before downshifting into 1st.

Note also that just cornering hard consumes energy and slows a car down. When cornering hard, my guess is that cornering slows down a car more than engine braking does. I do use the throttle to control how fast the car slows down in a turn, while approaching the apex.

When watching an analisys of a fast lap, I've heard the the expression, "no hint of a lift, just the g forces slowing down the car" more than once, as in this video. I get the impression that F1 cars don't rely on engine braking at all, based on the when the downshifts occur.

spaf1.wmv (http://jeffareid.net/real/spaf1.wmv)

[skiingman]

It depends on the car. In real life, many racing cars have their clutches setup to limit the amount of engine braking, probably for two reasons: 1. to keep the rear tires from sliding; 2. to keep the engine from over-revving.

Like motorcycle slipper clutches? In the cars you are talking about, is this done through electohydraulic clutch control, or a mechanical system like the motorcycles? For anyone not familiar with the idea, here is a good link : http://www.sigmaperformance.com/slipperclutch.html

I get the impression that F1 cars don't rely on engine braking at all, based on the when the downshifts occur.

spaf1.wmv (http://jeffareid.net/real/spaf1.wmv)

Yeah I have that understanding too. I think they do add more engine braking to the throttle-closed ECU settings when they have good reason.

[KurtG85]

no racing driver in their right mind would just brake into a corner and then select the right gear before the apex or before you go on the power.

I was wondering why it would be so ridiculous for a driver to do this if he had his brake power setup so hes able to lock the wheels with little effort with only foot braking (and therefore threshold brake without help from the tranny)? Of course i can understand why you wouldnt put it in gear after turning in, but im wondering why it would be so insane to brake with just the brakes until reaching a safe speed to put it in the right gear for the corner, and then turning in?

[skiingman]

Of course i can understand why you wouldnt put it in gear after turning in, but im wondering why it would be so insane to brake with just the brakes until reaching a safe speed to put it in the right gear for the corner, and then turning in?
Its not insane in the least.

As is kind of alluded to above re: slipper clutches, this is pretty much exactly what happens in racing motorcycles. Engine braking is limited to just about nothing, in the interest of consistency and smoothness.

As is made obvious with the new BF1 in LFS, the ECU is used in racing cars for a similar effect, although more easily adjustable.

[Thorvertonian]

this is pretty much exactly what happens in racing motorcycles. Engine braking is limited to just about nothing, in the interest of consistency and smoothness.

Are you trying to say they don't use engine braking in motorcycle racing??????

If yes that's an insane opinion,
if not, sorry!!!!