Trail braking 101
#46
Rennlist Member
Utkinpol,
As I mentioned it is important to have the whole heel/toe down which includes getting allthedownshifting done in a straight-line prior to corner turn in. It's important to understand that trailbraking is only The difference between ending all your braking before turn in and breathing off the brakes just prior to the apex. Downshifting does not change. You typically never want to downshift in a corner due to the potential for it to unsettle the car. If you need to downshift in a corner you didn't get your corner entry done correctly. Two different things.
As I mentioned it is important to have the whole heel/toe down which includes getting allthedownshifting done in a straight-line prior to corner turn in. It's important to understand that trailbraking is only The difference between ending all your braking before turn in and breathing off the brakes just prior to the apex. Downshifting does not change. You typically never want to downshift in a corner due to the potential for it to unsettle the car. If you need to downshift in a corner you didn't get your corner entry done correctly. Two different things.
i always prefer to ask about stupid stuff than to try it in a car. works a bit better this way.
#47
Race Director
...so considering all what was said above - how exactly does one choose when exactly to let clutch go? should it be done even before entering the turn at the end of the straight when you have max pressure on brakes, at the middle of trail braking zone, or at exact moment when foot goes off brake pedal completely? Or something totally else? I looked over this thread from beginning but did not get a feel that this aspect was explained sorry if I overlooked. ...
So you must master heel and toe downshift as that allows you do the downshift as you are braking. This a fundamental skill.
Once mastered you can throw turn while braking in the mix as well.
When you execute the down change depends on RPM. If youi have long corner entry you will find the need to brake during corner entry and also be downshift as well.
One classic corner we have at a local track goes like this.
Entry is down the main straight. 115 mph in 944 spec or maybe 140 in fast high hp car.
For the 944 we wait till the last moment get on the brakes hard in straight line downshift then turn in while still braking. Downshift to 4th while still braking down to the apex. Then once slow down eniugh at near the apex downshift again to 3rd and get right back on the gas. Done right we will be turning 5000+ rpm in 3rd and full throttle all the way out of the corner. Of course we are al the limit of grip all the way around corner entry. I would guess 10% of speed reduction is done in straight line. The rest is all after turn in with a significant cornering load on the chassis.
If we were just braking in straight line we would have probabyl 7-8 car lengths of neutral throttle at 4500 rpm in 3rd and maybe 65 mph. And of couse be passed like we a standing still as turn in speed is probaby right about 95 or 100 mph by using trail braking. Min apex speed is probably 70 mph.
The other cool thing about trail braking is done well you can run a faster apex speeds since you can use the weight transfer off the rearend to make the car turn. It sort of feels like a controlled spin in the way you can get the back end ot rotate.
Trail braking is very powerfull skill and really seperates the men from the boys in track driving. Winning races and getting fast laps does not occur on straight aways, or corner exit. Those areas to pretty easy for any one to master. Even mid corner is not too hard. However braking and corner entry are hard to do and that makes then the place races are won and lost. Even with pros most drivers make a mistake not on corner exit, but at corner entry. Even if they go off on corner exit it was because of a mistake going into the corner.
That said you cannot let corner entry speed degrade corner exit speed. Slow in fast out is good for DE. However in race you need fast in and fast out. The challenge is that fast in done wrong means slow out. Getting it right is a very delicate balance.
#48
Race Director
Turn 1 at firebird main and Turn 2 at PIR. Same for turn 1 at miller. All require the downshift after turn in. Else you will be slow. If you try to downshift to the right gear going straight you will either overrev the motor or be just plain slow.
Granted changing gears in corner is not ideal, but there are many place it is just required. That is on reason sequental boxes that blip the throttle are so handy. It make the downshift easier and more precise.
#49
Rennlist Member
Joe,
Absolutely agree, but this thread is trailbraking 101, thats more of a 201 course...
I'm trying to break it down to minimize the confusion between straightline braking downshift/heel/toe/trailbrake/move my braking zone/oh **** i'm out of track... for folks just moving from straightline braking into trailbraking they need to understand the basic principal, then you build on that...
See you saturday, going to be an early one....
Absolutely agree, but this thread is trailbraking 101, thats more of a 201 course...
I'm trying to break it down to minimize the confusion between straightline braking downshift/heel/toe/trailbrake/move my braking zone/oh **** i'm out of track... for folks just moving from straightline braking into trailbraking they need to understand the basic principal, then you build on that...
See you saturday, going to be an early one....
#50
Rennlist Member
For the 944 we wait till the last moment get on the brakes hard in straight line downshift then turn in while still braking. Downshift to 4th while still braking down to the apex. Then once slow down eniugh at near the apex downshift again to 3rd and get right back on the gas. Done right we will be turning 5000+ rpm in 3rd and full throttle all the way out of the corner. Of course we are al the limit of grip all the way around corner entry. I would guess 10% of speed reduction is done in straight line. The rest is all after turn in with a significant cornering load on the chassis.
If we were just braking in straight line we would have probabyl 7-8 car lengths of neutral throttle at 4500 rpm in 3rd and maybe 65 mph. And of couse be passed like we a standing still as turn in speed is probaby right about 95 or 100 mph by using trail braking. Min apex speed is probably 70 mph.
If we were just braking in straight line we would have probabyl 7-8 car lengths of neutral throttle at 4500 rpm in 3rd and maybe 65 mph. And of couse be passed like we a standing still as turn in speed is probaby right about 95 or 100 mph by using trail braking. Min apex speed is probably 70 mph.
Down shifting to 4th gets done as at no time you should be in a turn with constantly depressed clutch, is it correct? I just got a feel from that section you never go on gas while on 4th gear, correct?
Very interesting read, thanks. It will probably take ages before I will be able to work clutch in a corner without upsetting the car, for now it is not in any plans at all. I had a constant struggle at NHMS trying to understand just on mental level where exactly in those 1-2b corners up and down shifting supposedly should be done, as even with not doing any of it there and flowing steadily through on 3rd gear it was obvious that car will fly aside easily if any mistake is done there. Not all the corners are same obviously, but, still, thanks for the explanation.
#51
Race Director
Joe,
Absolutely agree, but this thread is trailbraking 101, thats more of a 201 course...
I'm trying to break it down to minimize the confusion between straightline braking downshift/heel/toe/trailbrake/move my braking zone/oh **** i'm out of track... for folks just moving from straightline braking into trailbraking they need to understand the basic principal, then you build on that...
See you saturday, going to be an early one....
Absolutely agree, but this thread is trailbraking 101, thats more of a 201 course...
I'm trying to break it down to minimize the confusion between straightline braking downshift/heel/toe/trailbrake/move my braking zone/oh **** i'm out of track... for folks just moving from straightline braking into trailbraking they need to understand the basic principal, then you build on that...
See you saturday, going to be an early one....
#52
Rennlist Member
Jim,
Turn 1 at firebird main and Turn 2 at PIR. Same for turn 1 at miller. All require the downshift after turn in. Else you will be slow. If you try to downshift to the right gear going straight you will either overrev the motor or be just plain slow.
Granted changing gears in corner is not ideal, but there are many place it is just required. That is on reason sequental boxes that blip the throttle are so handy. It make the downshift easier and more precise.
Turn 1 at firebird main and Turn 2 at PIR. Same for turn 1 at miller. All require the downshift after turn in. Else you will be slow. If you try to downshift to the right gear going straight you will either overrev the motor or be just plain slow.
Granted changing gears in corner is not ideal, but there are many place it is just required. That is on reason sequental boxes that blip the throttle are so handy. It make the downshift easier and more precise.
It wsa quite interesting to read W.Roehl interview stating that he did run around ring with PDK in fully automatic mode and it resulted nearly close to his time with manual shifting - so, is it really something close to reality and people are actually able to run around track using advanced techniques with PDK in fully automatic mode? Not if I would ever had car with it, but, who knows.
Essentially - can PDK efficiently downshift in a corner without upsetting the car?
#53
Rennlist
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Larry Herman
2016 Ford Transit Connect Titanium LWB
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
#54
Rennlist Member
#55
Race Director
Now clearly if are only going to DE you don't need to get to this level, but it is the level every solid racer needs to be at.
As for the clutch it should always been engaged unles your are actually moving from one gear to th next. Never hold it down for anything more than a second or so. The except is a spin where you want to go both feet in. Of course when do to that you are not trying to be fast, but just limit the damage.
Very interesting read, thanks. It will probably take ages before I will be able to work clutch in a corner without upsetting the car, for now it is not in any plans at all. I had a constant struggle at NHMS trying to understand just on mental level where exactly in those 1-2b corners up and down shifting supposedly should be done, as even with not doing any of it there and flowing steadily through on 3rd gear it was obvious that car will fly aside easily if any mistake is done there. Not all the corners are same obviously, but, still, thanks for the explanation.
In any event a down change should be so smooth a passenger would not feel it occuring. If their head jerks forward it still too rough. So practice practice practice. It takes time.
#56
Race Director
what do you think of PDK cars on a track? i have heard somebody saying that in some cases PDK does not really downshift exactly when button is pressed.
It wsa quite interesting to read W.Roehl interview stating that he did run around ring with PDK in fully automatic mode and it resulted nearly close to his time with manual shifting - so, is it really something close to reality and people are actually able to run around track using advanced techniques with PDK in fully automatic mode? Not if I would ever had car with it, but, who knows.
Essentially - can PDK efficiently downshift in a corner without upsetting the car?
It wsa quite interesting to read W.Roehl interview stating that he did run around ring with PDK in fully automatic mode and it resulted nearly close to his time with manual shifting - so, is it really something close to reality and people are actually able to run around track using advanced techniques with PDK in fully automatic mode? Not if I would ever had car with it, but, who knows.
Essentially - can PDK efficiently downshift in a corner without upsetting the car?
#57
Race Director
#58
Rennlist
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The PDK makes lightning upshifts because it pre-selects the next gear up, and only has to switch clutches. The downshifts are a good bit slower, but still acceptable as compared to a manual. It will delay the downshift if your revs are too high for the next lower gear.
#59
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