braking points

[MarkG]

Has anyone got information or a formula that can determine the effect on lap times, by using different braking points into a very slow corner from speed, such as a hairpin??

[MGDavid]

If only it were that easy! Unless defending a position it's often quicker to brake less than maximum, for a longer distance, settles the car better, and remember - slow in, fast out. Or so my mentor tells me... personally I'm a demon late braker by nature and having trouble dropping the habit :-(

[Adam43]

Well with a bit of thought you could use the basic formulas of motion, although in there simpliest form they only consider constant acceleration. This is not the case under deceleration, but maybe you can find a decent approximation.

*goes away to find a web page, so I don't have to type in equations here*

Ah here we go: http://physics.about.com/cs/acceleration/a/060703.htm
A couple of years ago I did a few back of the envelope calculations to calculate what a change in mass and power would have on lap time.

For theory you'll have define quite carefully what you mean by your question. Are you saying each different braking point does not effect the cornering speed. Will you consider the change of terminal speed before the braking? etc... etc...

In practice! Well there are a lot of factors...

[shiny side up!]

Yes, as Adam points out that is a very difficult / intricate question.

If you are trying to see what kind of advantage being a demon late-braker and staying on the throttle an extra 5 or 10 meters, I can tell you right now it isn't worth your time to figure out the maths, because you are in all probability going to be slow and very hard on equipment...

[midgetman]

Listen to shiny side up, MGDavid, listen well.

LOL

Your Mentor!

[gfm]

The key issue with braking is to do as little of it as possible as it only slows you down.
Not only that, really demon late braking does as fellow pundits do allude to here, mean bags of unwanted dive and other unnessary movements for the chassis and tyres to cope with, which all takes time to unravel.
The other tip must be to be that very minute change in HOW you PUT the brakes on, APPLYING them not HITTING the brakes. Also the same applies in reverse. Start coming OFF the brakes a little earlier, allowing the car to BREATH.
This isn't a formula though. So many incalculables perhaps.

[MarkG]

thanks for responding guys. I tend to agree with 'shiny side up' because my general approach is to try and focus on exit speed, so I'm not a demon late braker. Having said that, I reckon I need to improve my technique where heavy braking is required. I know I do, because guys go past me into hairpins

[Revracing]

very late breaking only works if you and your car are capable of carrying the surplus speed through the corner, if you cannot you will scrub speed and kill your corner exit and your lap time.. but it is possible

[zefarelly]

In my few races I've thought I could outbrake other cars and gone skidding into corners, run wide and watch them grin as they cruis past ! I guess I wont make any freinds if I hit anyone either !

having said that theres a fine line between that and getting pipped into a corner byt the car behind,

still learning here, and probably will be for some years, or decades to come !

[StephenRae]

I instructed for years and found this worked.
Instead of experimenting with leaving your braking later and later with the inevitable outcome, brake at the point you feel prudent but instead of braking hard enough to slow down to a suitable speed for turning in, brake as hard as you can.
The outcome usually is that you find you are braking much too early and consequently can leave your braking later next time...but still braking just as hard.

[Tim Falce]

Originally posted by StephenRae
I instructed for years and found this worked.
Instead of experimenting with leaving your braking later and later with the inevitable outcome, brake at the point you feel prudent but instead of braking hard enough to slow down to a suitable speed for turning in, brake as hard as you can.
The outcome usually is that you find you are braking much too early and consequently can leave your braking later next time...but still braking just as hard.

I am one of the late brakers and find that it does no good at all. When I try early braking as you describe I then have to drive up to the corner. I never seem to get it exactly right.
I find it very difficult to use reference points on the track (except for the first corners at Croft and Donington which is the pit lane exit lines) and normaly have to just look at the corner and judge the distance.

[gttouring]

much as has been said slow in fast out- but this is relative.
if we have 200 meter markers broken in 50 meter increments
where do you start to apply? if the coming corner is a 1st gear or 2 nd gear hairpin?
well car power affects this, car brake size and TYRES! big diameter wide? slicks- treaded- multiuse, road going...
car type, any downforce?
i rmeber entering a bustop at a track during some praccy, formula ford.
it was a 4 th gear lead in and had to drop to 1st (although 2nd gear would do it comfortably, really fast guys went to 1st i later discovered.)
150 meter out 3 cones.
after cone 2 (when your butt passes it) every one went gear changing and braking...getting a good dive on the car and turning in right after the last cone...tight corner car swung it wide had to pull it tight to set up for the next corner...
2nd gear no drama more brakes and slower in and out, but less lock up s and plowing through the last cone.
1st gear a bit trickier as too much enthusiasm would lead to lock up and missing turn in.
it is as we all know a delicate balance.
slow in indeed, but slow compared to who?
my slow in was to slow, my faster and slower entry speed (1st gear) was tricky and lots of hard braking although the gear changing kept pressure from full.

[MarkG]

I find StephenRae's reply interesting, maybe because his suggestion is the technique I plan to adopt at my next test session, and I have a plan My thinking is this:- If you take 2 braking points, A and B. B is the maximum braking point to still enable carrying speed into the tight corner and having a good exit. Point A is 4.9 yards before point B. The reason I pick 4.9 yards is because that's how far one travels in 1 second at 10mph, and I'm purely guessing here, that maybe one takes off 10mph between points A and B. If I'm right about the 10mph, then braking at point B will reduce my lap time by 1 second !

[shiny side up!]

I don't think your math there is quite right, but maybe I don't understand what you are trying to say. But you can rest assured that easing off throttle/onto the brakes 5m earlier (point A) is not going to lose you a second a lap; in fact, you will be faster in general because the car will behave better in the corner and let you get the power down as early as possible.

Another thing I can tell you is this: If point B "is the maximum braking point to still enable carrying speed into the tight corner and having a good exit" as you posted, then you should be braking at point B. Emphasis on the 'good exit'! But if point B really means "man, I can pull 2 car lengths under braking, but then all hell breaks loose and I have to stand on my head to keep it out of the beach", then point B is too deep because it is hurting your exit speed...

A couple of years back I read an interesting article comparing Michael Schumacher's braking/turning at the hairpin in Montreal to Rubens' technique. Michael actually got on the brakes earlier and was slightly slower just before the apex, but was quicker overall through the corner by a not unsubstantial margin. Braking hard and getting through the corner quickly are all about weight transfer and finesse!

[StephenRae]

Originally posted by falcemob
I am one of the late brakers and find that it does no good at all. When I try early braking as you describe I then have to drive up to the corner. I never seem to get it exactly right.
I find it very difficult to use reference points on the track (except for the first corners at Croft and Donington which is the pit lane exit lines) and normaly have to just look at the corner and judge the distance.

The purpose of the advice was for the driver to demonstrate the capabilities of the brakes to himself. Once appreciated I'm with you, the later the better, it doesn't really matter what shape you are in so long as you can get the power down early for the following straight.

[archibold]

I'm not sure it's as simplistic as some people suggest. There are definitely different styles which work better in different types of car.

For instance I can think of a senior instructor at Silverstone who can number many many front wheel drive race wins over a large number of years. He brakes far earlier than most but then sets the car up very early and carries more speed through a corner than most people think is possible....there is a definite finesse to this...though it may not suit all cars/driver types.

[MarkG]

It is not the 'slow in, fast out' element I am learning to discover. In fact, I feel I make up good time on cars with this approach. It is the fact that I feel I am braking earlier at the sort of corners like Hatchetts Hairpin at Pembrey, and costing me time. I believe I can brake later than I do at this type of corner, and make up time accordingly, but I need to sort of retrain my approach to this type of corner. In other words, I don't think I am using point B, as mentioned in my recent post.

[zefarelly]

I find braking points somewhat misleading, in the Dunlop circuit guide for examplke, its great to learn circuit info, but my cars not fast enough for much of it to be relevant . . . .If I was in an F3 car it may be wrong again but on the other side of the scale . . . .I can safely brake later as I dont have to scrub off as much speed.

[StephenRae]

Archi...your right, front wheel drive is completely different, I think you have to be done with slowing down earlier and have the car in an attitude such that you can put the power down without understeering straight on.
I read somewhere that understeer is when you can see the accident coming and oversteer is when you can't!

[Red Dog]

I would say the difference between braking at the optimum and braking too late is half a metre or less. If you brake 2 metres before optimum you will be braking gently in comparison. If you brake late enough to miss your apex by half a metre your exit speed will be affected. If you brake a little early but more gently you will lose a very little time on entry but nothing as you exit. If the driver close behind gets it right and you are slightly late you will almost certainly be overtaken on the next straight (all other things being equal) as he will carry more speed through and, critically, on the exit of the corner.

[Mackmot]

bloody thing, I just spent ages telling you all how to brake but the image I attached of an actual traction circle was a few bytes too big and I lost my reply. Cant be bothered thinking about it again tonight, I might reply tomorrow.

[Woolley]

Originally posted by StephenRae
I read somewhere that understeer is when you can see the accident coming and oversteer is when you can't!

That'd be me, then! The other quote - Will Hoy, I think - was that with rear drive, you can be a hooligan on the way in and the way out, but must be very precise at the apex. Front drive is the opposite.

Remember also slip angles - tyres have a finite amount of grip which can be used for braking or for cornering. If you do both together then you can only use a percentage of each. I read the really fast drivers, the ones who can carry speed all the way through the corner, continue their braking all the way to the apex, using the slip angles to change the attitude of the car and gain extra cornering. Sadly, I don't race, so I haven't tried it, but I'd be interested to see what those of you who do have to say?

[shiny side up!]

That would be illustrated by the traction circle that poor Mackmot just spent ages trying to post, Woolley!

Hopefully Mackmot gets up the energy to try posting it again...

[dtype38]

Unlike my mate Falcemob, I always use reference braking points. I'm hopeless at judging braking by just looking at a corner, so I set about it more systemtically. I start by picking some reference (like a marshall post or turn board) well before the real braking point, say 10-20yds. I approach the corner at full race speed had brake as hard as I can (being progressive and all that) at my chosen point. The important bit here is that I now ignore the corner and think only about the speed of the car. I come up off the brakes when I've got the speed down enough and feel for the "turn in" as the pitch settles, all the time pretending that I'm on perfect line. Only now do I look at the corner and see how short I am of the real perfect apex line. Next time round I move my braking point forward by about 2/3 the distance I was short of that perfect turn in point. The reason for only moving it 2/3 is that with the braking point further forward theres a longer run from the previous corner, and therefore more speed at the braking point - meaning a longer braking zone. If the turn in is still short then the process can be repeated.

Two words of caution with this system: First, I try not to get into the habit of using something like a patch of different coloured tarmac as a brake point... sometimes it close racing another car can obscure the view and cause you to miss it entirely (been there, done that). I try and get a fix on things higher up off to both sides. Second, you need to take into account how well you took the previous corner. Using Pembury, for example, if you get pushed wide in Honda and have to get out of the throttle to make the exit kerb, then braking for the Hairpin will be later than if you get a superb clear line round Honda (which means you arrive at the hairpin faster)

good luck

[StephenRae]

Originally posted by Mackmot
bloody thing, I just spent ages telling you all how to brake but the image I attached of an actual traction circle was a few bytes too big and I lost my reply. Cant be bothered thinking about it again tonight, I might reply tomorrow.

I found this which will be of interest and it will save you an evening wrestling with your computer.

http://www.miata.net/sport/Physics/07-Circle.html