Downshifting mid-turn vs. while braking

[calexand]

I have always seen good drivers downshift as they enter a corner, and have done so myself. But doing so either requires heel-toeing to keep braking while downshifting with appropriate throttle, or repeatedly stopping braking for a second to engage each lower gear with some throttle. If I could just flip a paddle while slowing down, it would be fine, but since I have to heel-toe or move my foot off the brake, it really is clumsy.

So instead, lately I have been just leaving the car in whatever gear I was in while braking as I enter a corner or exit ramp, downshifting to whatever exit gear I want as I am cornering (when I would not be using the brake or throttle since I am putting the tires to work on maximum turning) and then coming off the clutch in that new gear as I start accelerating out of the corner. It seems to work quite well, no matter how many gears I drop down at once in that shift. Can anyone think of a reason not to do this? There must be one, or I wouldn't see so many drivers downshifting while braking...

Chip

 

[vtecNSX1]

Im pretty sure ur not sposed to shift while cornering. At least thats what i was taught. I always downshift to whatever gear i want before the corner so i can be in the powerband for a quick exit.

 

[NeoNSX]

You should never downshift when cornering because you should have both hands on the steering wheel. It's a lot safer. If you lost traction while downshifting with one hand on the wheel, you'd be in a lot of trouble.

I completely agree with <B>vtecNSX1</B>'s comments, especially about a quick exit.


Anyhow, that's the general rule... but rules are made to be broken.

 

[SaberX]

I believe (and I'm sure many people will correct me if I'm wrong) but having the car in gear affects the "balance" and suspension load of the vehicle. I don't think that having the car out of gear (for even a small time) during cornering is considered a good thing. Also, the re-engagement of the clutch if not smooth and rev matched could upset the suspension load potentially even to the point of oversteer - depending on conditions. Plus there are all the reasons people mentioned above... besides every corner is an excuse to practice heel-toe like a pro.

 

[calexand]

Good observations. Thanks!

Chip

 

[CDub]

SaberX explained it really well on upsetting the balance of the car when re-engaging the clutch during a turn. This applies to both track and aggressive street driving and its less safe.

On the track, all braking and shifting should be done before you even start making a turn. You should be on the gas during a turn so that weight is transfered to the rear wheels to maximize traction for faster track-out speed.

Street driving is not as critical on track-out speed, but a habit is hard to break if you ever decide to track you car. You may have track days a few times a year, but you drive everyday. So astablishing a good habit will help you on the track.

 

[SilverOne]

...This applies to both track and aggressive street driving and its less safe....

hehehehe.., aggressive street driving, isn't that why we go to the track to avoid

 

[fkong777]

If possible braking and shifting should be done at a straight line before the corner. When you at the correct gear in a corner you can throttle balance that car so you will get out of the corner quicker.

More often than not you will end up downshift at exit and really slow down your cornering and exit speed.

It may take some practice but you have heel toe to a stop at every stop light. I find it that the faster I perform the heel toe downshift the smoother the gear transition gets.

 

[Bobby_Generic]

If you are shifting of braking during a corner then most likely you are just covering up for a mistake you just made

 

[Mark911]

When and how to downshift will always be a source of varied opinions, but my theory is what’s more important is that you should be either on the gas or on the brakes (compression is a form of breaking but it’s not very predictable) and rarely if ever coasting. That means being able to transition from breaking to acceleration (in a turn even keeping your speed constant is actually accelerating) quickly and smoothly. Heal and toe is the way most people match engine speed with rear wheel speed for that smooth transition. Problem is, it’s tough to do. I found a trick that helps me on the track. I simply removed my cruse control motor and replaced it with a starter solenoid. I wired up a switch to my shift lever and whenever I need some revs I simply “hit the button”. By modulating how long I hold the button down I can vary and hold steady my rpm all the way up to redline. Very simple and effective, if not a bit lazy . . . . . .

 

[docjohn]

If you are able to downshift midturn and not wad it up you are not driving near any limmits and therefore are not in danger.But it is worrisome to do something unsettling to the car because you find it difficult to heel and toe properly during straight-line breaking before turn-in.If you can't properly rev-match the throttle blip while breaking in a straight line ;then fouling it up while carrying cornering forces is folly.

 

[NSXDreamer2]

[/QUOTE]If you can't properly rev-match the throttle blip while breaking in a straight line ;then fouling it up while carrying cornering forces is folly.

Amen.... NO offense.

now what about upshifting after the apex?? I found myself repeatly do that both on street and track...

 

[calexand]

When and how to downshift will always be a source of varied opinions, but my theory is what’s more important is that you should be either on the gas or on the brakes (compression is a form of breaking but it’s not very predictable) and rarely if ever coasting. . . .

I think there have been some great comments here. The one that I found most compelling was that if I am cornering with one hand on the wheel and/or the car not in the right gear (or on clutch) during the corner, I will be totally hosed if the car starts to spin (due to gravel, etc.). That is a great reason to have both hands on the wheel and power available at the right ratio to throttle out.

This comment above is the only one I disagree with. At the BMW car control clinics, they make a point of repeatedly saying that you can ask your tires to brake/accelerate or ask your tires to corner hard, but should not ask them to do both at once. So they have you brake, then ease off the brake as you turn harder, then ease onto the throttle as you straighten out the wheel. They talk about a string between the wheel and pedals so if you are turning the wheel hard you have no pedals down as you will otherwise be asking the tires to do too much. It all made sense, and I think that as you are cornering the hardest, you should not be on either pedal. Thoughts?

Chip

 

[docjohn]

There will be a very small point in time when in fact you are transitioning to the throttle from the brake when you could say you are doing nothing but this is for fractions of a second.You don't want to coast through a turn!Plus very good drivers can left foot brake and mess with the throttle at will making for some real dancing.I don't use left foot braking in the nsx.

 

[apapada]

I think there have been some great comments here. The one that I found most compelling was that if I am cornering with one hand on the wheel and/or the car not in the right gear (or on clutch) during the corner, I will be totally hosed if the car starts to spin (due to gravel, etc.). That is a great reason to have both hands on the wheel and power available at the right ratio to throttle out.

Cars, especially RWD cars, and specifically Mid-Engine RWD cars do not need any gravels or oil or [Fill the blank] to start oversteering and spin out of control. Just upsetting the suspension alone will do it. Being close to the limit and downshifting carelessly will have the same results as pulling the e-brake while cornering.

This comment above is the only one I disagree with. At the BMW car control clinics, they make a point of repeatedly saying that you can ask your tires to brake/accelerate or ask your tires to corner hard, but should not ask them to do both at once. So they have you brake, then ease off the brake as you turn harder, then ease onto the throttle as you straighten out the wheel. They talk about a string between the wheel and pedals so if you are turning the wheel hard you have no pedals down as you will otherwise be asking the tires to do too much. It all made sense, and I think that as you are cornering the hardest, you should not be on either pedal. Thoughts?
Chip

This is correct as discussed and explained in
this thread (post #7 and subsequent posts).

 

[nsx1164]

now what about upshifting after the apex?? I found myself repeatly do that both on street and track...

For LONGER exit paths (from apex to turn exit), if you run out of rev, you may need to upshift -- if the wheels are straight at the time, you should be fine, even with some driveline jerk on upshift.

 

[NSXDreamer2]

.... They talk about a string between the wheel and pedals so if you are turning the wheel hard you have no pedals down as you will otherwise be asking the tires to do too much. It all made sense, and I think that as you are cornering the hardest, you should not be on either pedal. Thoughts?

My comment on this is that while you are at Street driving, coasting 50-60mph in fifth gear, your statement stands true somewhat. At the particular speed and gear, your car doesn't decelerate.

Now think of it on more spirited driving, (or track driving on the car's limit.) Weight transfer happens whenever you turn your wheel and "make any adjustment" on your pedals. As soon as you take your foot off the gas pedal, the cornering force will slow the car down, you also have to take account that most of us are turning in a lower gear while the engine rpm is higher thus the engine braking also take effect as soon as you take your foot off the throttle. These all leads to weight transfer to the front, and your rear end is coming around, a little of it (which in the first half second of the turn) helps our car dive into the corner, then we have to get back on gas (too late you waited then it'll spin!) to carry the car thru apex. Then you start giving more gas as you unwind the steering wheel.(less corner force=more acceleration) Most of us FWD drivers who never drive the nsx on the track will have to take a lot more practices on how to finese the throttle control to maintain the car balance.

 

[PKim]

now what about upshifting after the apex?? I found myself repeatly do that both on street and track...[/QUOTE]

If you have to upshift at apex, most likely your in the wrong gear. It is normal to hit the apex, track out and then upshift on the straight.

heel/toe is used primarily in turns that require you to downshift ie. from 3rd to 2nd, allowing you to be in the right gear so when you are transitioning from braking to accelerating you will have power out of the turn. Some turns like fast sweepers don't require you to downshift, you might be fine in 3rd gear for the whole turn.
The reason heel/toe is so important is that you are not using the engine to slow the car down, when you rev match the transition is smooth and not up setting the balance of the car. You are therefore relying on pure braking to slow you down which is more predictable and safer.
Entering a turn you should only be focused on steering, possibly braking (if you trail brake), and then accelerating, you should not have to focus on shifting since that part has been done prior to turn in.

You could learn to heel/toe in the street prior to every stop or turn. And start out slowly and when you have mastered it, you will be a better driver and will appreciate the nsx more

Cheers.

 

[Peter Mills]

The one that I found most compelling was that if I am cornering with one hand on the wheel and/or the car not in the right gear (or on clutch) during the corner, I will be totally hosed if the car starts to spin (due to gravel, etc.).
Chip:
Quick find a new hobby....One hand on the wheel?????
Spend some money come to NSXPO 2004 and learn how to drive that NSX!!!!!

 

[NSXDreamer2]

If you have to upshift at apex, most likely your in the wrong gear. It is normal to hit the apex, track out and then upshift on the straight.

I'm sure I was... here's the scenerio, coming off one tight corner in 2nd gear, before the turn in to the last corner to the straightaway, I'm around 6500 to 7100 rpm if I'm doing good exiting the last one, if I shifted to 3rd I will be having a relatively relaxing moment with this corner, and definately not getting as much speed... in this situation... maybe a short gear will help?? I've tried stayed at the second at 8000rpm until I totally get the steering wheel straight, seems like it's slower that way too. Real question is.. Should I??

 

[Andrie Hartanto]

If you are shifting of braking during a corner then most likely you are just covering up for a mistake you just made

This is totally untrue. There are several reason for this. If you are in advance stage, you pretty much push the car, engine to thelimit. Sometimes the gearing is not optimize for particular track and you have to do this. In a race, there is more of a reason since most cases someone is breathing down your neck and trying to pass you.

 

[calexand]

The one that I found most compelling was that if I am cornering with one hand on the wheel and/or the car not in the right gear (or on clutch) during the corner, I will be totally hosed if the car starts to spin (due to gravel, etc.).
Chip:
Quick find a new hobby....One hand on the wheel?????
Spend some money come to NSXPO 2004 and learn how to drive that NSX!!!!!

In case it wasn't obvious, the one hand on the wheel comment was regarding that I need to take one hand off to shift, and that could be a problem if the car starts to spin. Go back up to the top of the thread.

Chip

 

[W]

If you're downshifting while cornering, how do you throttle steer? Anywho, downshifting upsets the balance of the car and better done when going in a straight line.

 

[Peter Mills]

In case it wasn't obvious, the one hand on the wheel comment was regarding that I need to take one hand off to shift, and that could be a problem if the car starts to spin. Go back up to the top of the thread.

Chip

Chip:
I'm sorry. I thought you were talking about "real" road course high performance driving. You're talking about "make believe" street driving.
At 40 MPH you can do anything. At 90 MHP your right foot better not move off the go fast pedal or you'll be kissing your butt goodby.In "our" world once you've turned into the corner you're on the gas...period.That explains why the west coast cars were so slow at Infineon last year. You guys thought you were commuting.

 

[2slow2speed]

This comment above is the only one I disagree with. At the BMW car control clinics, they make a point of repeatedly saying that you can ask your tires to brake/accelerate or ask your tires to corner hard, but should not ask them to do both at once. So they have you brake, then ease off the brake as you turn harder, then ease onto the throttle as you straighten out the wheel. They talk about a string between the wheel and pedals so if you are turning the wheel hard you have no pedals down as you will otherwise be asking the tires to do too much. It all made sense, and I think that as you are cornering the hardest, you should not be on either pedal. Thoughts?

Chip

I'm not sure if anyone addressed the previous paragraph, what you are referring to is what is commonly known as trail braking, cars that are front engined and RWD/AWD usually require trailbraking to get the car to rotate with ease, the extra time spent on the brakes through the turn keeps the weight on the front tires which in turns keeps the car from understeering or pushing. This is usually the case with most stock BMW's (E30/E36/E46)

But the NSX being mid-engined rarely requires trail braking to get it to rotate properly on most 90 or lower turns, in fact once you develop the skills more than likely you will be on neutral throttle/slight positive throttle as you pass the turn-in point for the turn.

Of course there are exceptions to this rule, sometimes even on the NSX you will end up trail braking to maximize the lateral grip/corner speed for some types of turns (for example a constant radius 180 degree turn, or a decreasing radius turn)

There are other advanced techniques that can be used to get varous differet types of cars to rotate but that won't be too informative for this particular topic.