Discussion
For most positive effect, at what point does one release the brake when trail braking?
In trying to use this technique, I am coming off the brake just after turn in, but it doesn't seem to be making a huge difference to my change of direction.
For the avoidance of doubt:
- I am referring to circuit driving.
- Use of heal and toe downchanges is a given.
In trying to use this technique, I am coming off the brake just after turn in, but it doesn't seem to be making a huge difference to my change of direction.
For the avoidance of doubt:
- I am referring to circuit driving.
- Use of heal and toe downchanges is a given.
Normally you blend the braking and the steering together so that the total loads you're placing on the tyres remain roughly constant. The weight transfer as you come off the brakes will usually affect the balance of the car and you can control this by how and when you come off the brakes, this might lead you to change the timing/speed of the transition to get the handling you want.
Try some experimenting.
Take a bend a few times by doing all your braking in a straight line.
Then consciously delay the time when you lift off the brake until after you have begun to get the car turned.
That back-to-back evidence should immediately manifest how braking with lock on will turn the car more than braking whilst heading straight.
'Trail braking' and 'braking on turn in' are two different things really:
Trail braking: This refers to blending the braking into steering for a long period after turn in, much as one comes onto the throttle on the way out of a turn, enabling one to brake later into the turn. Try here: http://www.getfaster.com/Techtips/Physics23.html
Braking on turn in: This is primarily done to set the attitude of the car on turn in to how you want it. If you come off the brakes then turn in afterwards, most cars will understeer strongly on the limit; or below the limit on the road you will feel a strong imbalance in the car as it leans on the front grip more than the rear. As you make the release of the brakes later and later you should get less and less tendancy to understeer, eventually a sweet spot of neutrality and then beyond that into oversteer. This is different from trail braking as you're not trying to do this to brake later, moreso to use braking as a way into fiddling with weight transfer to achieve what you want to. Obviously though trail braking does affect the car's balance, so this changes how you turn in on the brakes.
This is used to set the attitude on entry to corners just how you want it. For instance, I used to race a front wheel drive car. It would be beautifully netutral at high speed, but as the bends got slower, the more the car would want to understeer as you came on the power. To counteract this you would brake whilst turning in to create very slight oversteer in medium speed bends and stronger oversteer in slower bends.
Here's the entry to a bend at Oulton Park, whereby I am neutralising the car on turn in to achieve just this. It's subtle at this medium speed of corner, but you can see it:
Notice also how the chap behind me has done it less, and has slightly more understeer.
The idea being that when you exit any bend you're free to come on the power as much as possible and as early as you want to, without having to hold back for fear of understeer:
Notice how I'm not steering much, so at this point I can give the car lots of throttle. The car is actually drifting sideways there and will kiss the exit kerb.
You can also use this control over a car's attitude to put it off-line to overtake. For instance, here's me going round the outside of a car or two on the opening lap of a race at Silverstone at Luffield corner:
I needed the oversteer to control the car on that dusty part of the race track and complete the overtaking manouvre. It also allowed me the ability to accelerate as hard as possible to ensure I stayed ahead on the next straight, not to mention blocking the other chap's usual exit line.
I'd like to give some rear wheel drive examples, but being relatively new to Caterham racing I don't really have enough pictures to select any good ones showing these points.
Trail braking: This refers to blending the braking into steering for a long period after turn in, much as one comes onto the throttle on the way out of a turn, enabling one to brake later into the turn. Try here: http://www.getfaster.com/Techtips/Physics23.html
Braking on turn in: This is primarily done to set the attitude of the car on turn in to how you want it. If you come off the brakes then turn in afterwards, most cars will understeer strongly on the limit; or below the limit on the road you will feel a strong imbalance in the car as it leans on the front grip more than the rear. As you make the release of the brakes later and later you should get less and less tendancy to understeer, eventually a sweet spot of neutrality and then beyond that into oversteer. This is different from trail braking as you're not trying to do this to brake later, moreso to use braking as a way into fiddling with weight transfer to achieve what you want to. Obviously though trail braking does affect the car's balance, so this changes how you turn in on the brakes.
This is used to set the attitude on entry to corners just how you want it. For instance, I used to race a front wheel drive car. It would be beautifully netutral at high speed, but as the bends got slower, the more the car would want to understeer as you came on the power. To counteract this you would brake whilst turning in to create very slight oversteer in medium speed bends and stronger oversteer in slower bends.
Here's the entry to a bend at Oulton Park, whereby I am neutralising the car on turn in to achieve just this. It's subtle at this medium speed of corner, but you can see it:
Notice also how the chap behind me has done it less, and has slightly more understeer.
The idea being that when you exit any bend you're free to come on the power as much as possible and as early as you want to, without having to hold back for fear of understeer:
Notice how I'm not steering much, so at this point I can give the car lots of throttle. The car is actually drifting sideways there and will kiss the exit kerb.
You can also use this control over a car's attitude to put it off-line to overtake. For instance, here's me going round the outside of a car or two on the opening lap of a race at Silverstone at Luffield corner:
I needed the oversteer to control the car on that dusty part of the race track and complete the overtaking manouvre. It also allowed me the ability to accelerate as hard as possible to ensure I stayed ahead on the next straight, not to mention blocking the other chap's usual exit line.
I'd like to give some rear wheel drive examples, but being relatively new to Caterham racing I don't really have enough pictures to select any good ones showing these points.
Edited by RobM77 on Friday 5th September 09:51
Edited by RobM77 on Friday 5th September 22:09
Thanks for your thoughts guys. Interesting reading.
Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
Edited by Get Karter on Friday 5th September 14:04
Get Karter said:
Thanks for your thoughts guys. Interesting reading.
Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
No problem at all - glad to be of help. Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
Edited by Get Karter on Friday 5th September 14:04
We can't approach the limit on the public road for safety reasons, but if you're anywhere near Basingstoke I'm happy to give a demonstration of the different effects possible.
RobM77 said:
No problem at all - glad to be of help.
We can't approach the limit on the public road for safety reasons, but if you're anywhere near Basingstoke I'm happy to give a demonstration of the different effects possible.
Would have loved to meet for a demo Rob, but geography is very much against it. I live hundreds of miles north of you.We can't approach the limit on the public road for safety reasons, but if you're anywhere near Basingstoke I'm happy to give a demonstration of the different effects possible.
If you are ever at Knockhill or Croft...give me a shout!
Get Karter said:
Thanks for your thoughts guys. Interesting reading.
Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
Rob did a good job of explaining how you can use braking to accomplish different things.Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
The term "trail braking" derives from the idea that you can abruptly pull your foot away from the brakes, in binary fashion, or you can lift it gradually, "trailing" away the pressure.
Apart from the effect of aeordynamic downforce, which does not apply to road driving, your car weighs X - the total weight on the four tyres, When you introduce a side force to the tyres, it's only that weight that works against the side force and keeps the car on the ground. In one sense, "handling" is about managing that weight amongst the four tyres.
When you accelerate, more of the weight X goes to the back, giving more traction to the back (for RWD and 4WD) and at the same time generating understeer because there's less weight holding the front tyres down to the road.
Braking is of course the inverse. More weight is put on the front tyres, so they have more grip, and at the same time the rear tyres lose some of their grip. This is why, under very hard, abrupt braking the back end of the car wiggles around and you might spin.
Whether it's "trail braking" or "braking on turn-in", it's all down to the fact that your shifting the balance of weight, and thus the balance of grip, towards the front.
Do you know about the concept of the "Friction Circle"? It's a term coined by the great Mark Donahue, who did not invent but probably focused on the technique of trail braking more than anyone else did. Check it out.
In some cars it is one of the factors that can make a significant difference to overall rate of progress. I usually bumble around in the lower third of the pack at track days in my 964RS. However during a half day instruction the same 16 year old car, which is on standard road tyres, in the hands of Sean Edwards (who posts on here regularly and is a top bloke) became the car travelling fastest round the circuit.
As well as being very smooth in all inputs, Sean braked much harder and later and during the trail braking phase used the continuing weight transfer to improve front end grip and turn in (very important on a rear engined 911). Result much faster entry and exit speeds without any fuss or drama. Needless to say my attempts to repeat what I had been shown demonstrated that trail braking is actually quite a fine art and though the principle is straightforwad the practice is less so.
As well as being very smooth in all inputs, Sean braked much harder and later and during the trail braking phase used the continuing weight transfer to improve front end grip and turn in (very important on a rear engined 911). Result much faster entry and exit speeds without any fuss or drama. Needless to say my attempts to repeat what I had been shown demonstrated that trail braking is actually quite a fine art and though the principle is straightforwad the practice is less so.
Edited by lowndes on Saturday 6th September 10:46
flemke said:
Get Karter said:
Thanks for your thoughts guys. Interesting reading.
Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
Rob did a good job of explaining how you can use braking to accomplish different things.Nice link Rob, thanks...I hadn't realised there was a distinction between 'trail braking' and 'braking on turn in'.
It tells me that what I have been trying is 'braking on turn in'. I will continue to practice it.
Trail braking, as defined in the article, is something that I will leave until I am feeling more adventurous!
The term "trail braking" derives from the idea that you can abruptly pull your foot away from the brakes, in binary fashion, or you can lift it gradually, "trailing" away the pressure.
Apart from the effect of aeordynamic downforce, which does not apply to road driving, your car weighs X - the total weight on the four tyres, When you introduce a side force to the tyres, it's only that weight that works against the side force and keeps the car on the ground. In one sense, "handling" is about managing that weight amongst the four tyres.
When you accelerate, more of the weight X goes to the back, giving more traction to the back (for RWD and 4WD) and at the same time generating understeer because there's less weight holding the front tyres down to the road.
Braking is of course the inverse. More weight is put on the front tyres, so they have more grip, and at the same time the rear tyres lose some of their grip. This is why, under very hard, abrupt braking the back end of the car wiggles around and you might spin.
Whether it's "trail braking" or "braking on turn-in", it's all down to the fact that your shifting the balance of weight, and thus the balance of grip, towards the front.
Do you know about the concept of the "Friction Circle"? It's a term coined by the great Mark Donahue, who did not invent but probably focused on the technique of trail braking more than anyone else did. Check it out.
Spot on Flemke. The whole point of motor racing is managing the balance of the car to achieve the maximum grip out of both ends of the car, and therefore the maximum speed out of a car in the corners. One of the reasons I love track driving so much is, so I've found out, because I have a very sensitive sense of balance. I get sea sick before the anchor has even been pulled up on a ferry, I have trouble as a passenger in a car, and I can't even read or sleep on trains! As far as motor racing goes, I worry too much about crashing, I occasionally miss gears changing up and I'm rubbish at starts, but that sensitive sense of balance seems to carry me through!Incidentally, trail braking was one of the things that made Jim Clark and Michael Schumacher stand out from the rest. They mastered the technique and if you watch them drive it's subtle but you can see how it gave them an advantage. To be honest, until you're a top three finisher I think it's best to concentrate on achieving that balance, being smooth and driving the right lines. Getting those things right will turn you into a great track driver and a winner at most levels of club racing. The sorts of things that one learns later on are threshold braking, trail braking and, if it's possible in your car, left foot braking.
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