Best way to slow down.

This is the ''N'' button thread all over again.

 

Wow- crazy thread!

I want to chime in to the OP- especially if you have an F1 car and if you are on the street- I would use the brakes to slow down but I would recommend staying in gear. You just never know when someone behind you doesn't slow enough and you need to get back on the power to get away. I try to keep in gear in my stick cars too but sometimes I admit I pop it in N and cost to a stop. One should always keep their surroundings in mind so if you like coasting in N and theres no one around- I really don't see the harm. I just wonder how fast the F1 system will go back into gear. I figure best to not find out in an emergency. I suppose you could try it out one day.

Track driving is very different from street driving. For track braking you brake really hard up front and then modulate away from that. For street driving you brake gently at first and then add braking to increase your decrease in speed. You do this for the benefit of your passengers- so their bodies can prepare for the stop because they are not aware of your going to the brakes before the forces are felt- whereas the driver knows and your body already prepares. Just different scenarios. Track driving will put tremendous wear and tear on the car and its parts. Street driving is much less so.

FWIW, I am not an expert driver, but I am proficient. I've had hundreds of sessions out on the track and Entropy and the other guys (and gals?- sorry for not listing all the names) say it as I have come to understand it.

 

The problem is, you cannot brake with the engine when the „N“ button is depressed

Or maybe you need to depress the “N” button when you are braking too hard with the engine and the car is spinning

 

Are you saying they downshift many gears because they're trying to apply some sort of engine braking technique? Not simply because they have a lot of gears and need to get down to the right one for exit??

OTOH, maybe it was the conversation...

 

Good post. I agree with everything you said but one thing... on track I brake genlty first then progressivley harder and harder... at Skip Barber ( and Jackie Stewart) they want you to slowly increase the tire patch in the front so the balace is not affected ... that is the chief cause of cars spinning in corners as the "weight transfer " is so abrupt. Smooth is fast in evertying!

But you can break smoothly - with significant force ... it does require practice...

 

Well said, and braking smoothly with significant initial force is tantamount to proper threshold braking technique, as is smoothly reducing braking input..

 

It's good that you highlight some of the differences between track and road driving technique. Very few people practise late braking on public roads (one of my mechanic friends excepted ).

The other big difference is as I mentioned earlier, F1-transmission vs. manual stick-shift transmissions. You don't have time to make multiple smooth downshifts in a stick-shift race car when cornering. It's more like staying off the brakes as long as you can then quickly slow to a suitable speed for exiting the corner, match a suitable gear (at times skipping 1-3 gears) and then go with it relying on what is hopefully a wide torque curve from your engine.

However with an F1-transmission it's different because it's easy to make seamless downshifts and reapply partial throttle while still in the middle of the cornering maneuver and repeat this a few times in a long corner. If you do left foot braking it's also possible to brake and be on throttle at the same time. The resulting effect of controlled throttle input while braking in a corner is to purposely cause a bit of slipping on the drive wheels... reduce understeer. Applying partial throttle also helps keep the turbos on the boil, your engine in its power band.

F1 DRIVERS DO APPLY THROTTLE WHILE BRAKING FOR FAST CORNERS, IN BETWEEN DOWNSHIFTS
If you still think I'm blowing hot air then have a look at this 2011 Nürburgring F1 onboard video footage (it helps if your viewer has jog control to forward/reverse step through the frames).

This 11 minute footage features live SPEED, GEAR, THROTTLE INPUT and BRAKING INPUT readouts. All the F1 drivers depicted perform multiple downshifts for corners and Schumacher and Button also consistently apply partial throttle during their cornering while other drivers especially Webber are less inclined. I think Button has a smooth driving style while Schumacher is simply one of the most aggressive drivers. Both drivers and even Vettel consistently apply brief throttle adjustments even when braking - the initial sequence with Schumacher starting the race is very telling.

Think about it - if you can actively steering the car with throttle and engine braking in the corner, you will be better set up for a faster exit than someone coasting through the corner after they brake. In racing a lot depends on how fast you can get back on the throttle.

Of course, you don't want to regularly apply throttle under braking unless your racing budget is covering the additional wear and tear on your brakes and transmission. Some F1 drivers are known to be harder on their equipment, for various reasons. But my point is that if you are purely racing, these techniques are valid and often provide the edge. If you worry about wear on your equipment outside of lasting through the event, then you are obviously settling for lower performance.

[ame=http://www.youtube.com/watch?v=yCbPaWD0Gvc]F1 2011 - R10 - Nurburgring Highlights onboard[/ame]

BTW, the DCT in my Cali30 will mesh a suitable gear within a few milliseconds (probably 20 ms) when I go from NEUTRAL back to being in gear. There is also NO JOLT to the chassis when this happens - it's completely smooth and then it's up to me to downshift if I want more torque and more acceleration. I recall the DCT gearshifts from the Cali30 DCT are 20 ms.

These are some of the fun reasons unique to driving a car with a DCT vs a manual transmission. You discover them when you play with the car and it helps to justify the car's $300K Canadiian pricetag. DCTs are still new for drivers and it takes time to appreciate their PROs and CONs.

 

Yes. Please watch the F1 video I referenced.

They do have a lot of gears but F1 transmissions do not require drivers to do multiple downshifts to find the right one. You can threshold brake and then downshift once, the remaining forward momentum of the car when you lift your brakes will then set you up nicely to accelerate from the corner. You still have to apply judgment and not just stab at the brakes and F1 paddles but that's a given if you want to be consistently fast in racing.

F1 drivers perform multiple downshifts because they can continue to modulate the progress and balance of the car using each gear as they decelerate, especially if the corner is long. They do not only rely on brakes and the steering wheel to decelerate and steer. You can affect the degree of understeer by manipulating throttle. This is achieved via subtle changes in driveline drag and the slip angles. The changes have to be subtle because such changes can result in very significant results at high vehicle speeds. You cover a lot of distance at high speeds so subtle effects are highly magnified.

Well, this conversation has been illuminating in many ways to say the least, unfortunately not all of them related to driving fast... but then boys will be boys.

Now... off to the library in my Cali30!

 

Thanks for the information and kind words guys. Yeah I should have said I usually would gently get on the brakes for a millisecond or two and then really dig into them on the track- I think its better for everything- any kind of abrupt movement is usually not what you want for driving or really any thing in life where weight distribution is important. Sometimes you might intentionally do it because its fun though!

 

F1 transmissions are sequential, like your Cali. You can't get down from, say, 6th to 2nd without going through 5-4-3. I have no idea what you're suggesting with the idea that you can "downshift once". You're not suggesting (using my example) taking a 2nd gear corner in 5th, are you?

Just to be clear, if it's a 2nd gear corner, you're going to take it in 2nd gear, regardless of the transmission. If it's a full manual, it takes a little longer, but I doubt F1 drivers were skipping gears much (if at all) back in the manual days.

Again, my point being that they downshift through the gears simply because they have to get down to the right gear. Not because they're specifically seeking "just the right amount of engine drag".

And, yes, in a lot of corners (most), you're getting to "maintenance" throttle before apex, and balancing through the corner. But at this point, your braking is already done; maintenance throttle is to balance and fine-tune the corner; it's not about engine braking.

 

My comment about downshifting once was to compare manual stick-shift cars to F1 transmission cars when they dive into a slow corner from high speeds. With a stick shift I normally gauge what speed I want to slow the car down to and shift to the appropriate gear as I complete the braking. I will skip gears to do this.

For an F1 transmission, if you watch the F1 gear selector display in your Fcar when you threshold brake from a high speeds to low speeds you will see the transmission can and will actually select lower gears for you. It doesn't matter if you are in manual mode. If you come to a stop it will put you in 1st gear.

So the F1 transmission does not require the driver to sequentially shift but the teams do not use this capability in a race car because it is more advantageous to manually shift. Just like with non-F1 transmission cars, we do not use automatic slush boxes for racing. I suspect it is also an F1/macho thing because they want the race car design to demonstrate the driver's skill.

I don't know if racers did but when I drove 6MT, I always gauged the speed that I wanted the car to be in and would skip gears for the downshift. People do understand some corners are 3rd gear, others 2nd and the odd 1st gear hairpins so you just brake hard enough to make the corner and you skip to that gear.

This is up to interpretation but if you watched the video you saw some drivers play the throttle with and without braking while they were in the corners while others, other times they just braked (coasted) and waited to get past the apex. If it were just a matter of getting down to the right gears, there would not be any differences between how these drivers used (avoided) throttle in the middle of a corner.

Engine drag is created by playing the throttle while in a lower gear.

In the video, some drivers will continue to add a bit of throttle throughout the corner, especially with Schumacher and Button. Whenever they lift throttle there will be driveline drag if the car is slowing down (as when it is cornering). Engine braking occurs whenever there is driveline drag. Your saying "maintenance throttle is to balance and fine-tune the corner" is in fact saying they are balancing the driveline drag by varying throttle.

 

In the days before paddle shifters... F-1 guys would routienly jump gears going into corners.... it was very common. in the 70's with the hewland boxes you could fry a gear by not slowing down enough but mostly drivers would do a 5-3- or 6-4-2 shift ... like at Monaco for the chichane... f-1 boxes had such tiny movement in the gear lever. most of them had it on a rotating shaft so first was down and away with 5th top and away.. so it was easier to grab a gear than in a road car.

as someone else posted... the F-1 boxes of today - dont alow you to skip gears, but you can program the RPM length and torque for each gear per track, as well as the map of the engine. getting the bite point on 1st is still really difficult - ask Hamilton at Hungary. lift coast is not a great thing to do on a track.. you want to either be accelerating or decelerating in gear at all time. any time in neutral results in wasted time.

 

Perhaps, but race drivers don't, and it's not because they want to employ engine braking. You keep trying to use the fact that F1 drivers go sequentially down through the gears (as if they had a choice) as proof that they're employing finely-tuned engine braking. They don't.

Yes, the transmission will downshift to prevent stalling. (This has nothing to do with threshold braking, it's nothing more than stall prevention.) But again, this is irrelevant to the discussion. The fact race drivers don't want the engine dropping to idle is not because they want to employ engine braking.

I'm sure it has absolutely nothing to do with ego. They don't want the engine dropping to idle and the s/w kicking in anti-stall shifting. The reason should be obvious - you don't coast through corners on idle. You balance with maintenance throttle, and you want the revs up for exit.

That's fine for the street, but not what you're going to do on a track. Your engine braking storyline is at best an incredibly fine (but largely uncontrollable) nuance to slowing a car (recall the thread title). If such a detail could possibly have any relevance, it'd be on a track.

Of course the drag is there. You started your argument claiming that drivers are seeking that drag because engine-braking is beneficial as it acts on the rear instead of the front. My point is they are not downshifting and playing the throttle because they are seeking to use engine braking. It's just plain old balance.

 

I watched the video... what i saw was braking - down shifting into the proper gear .. while entering the corner... acceleration and tap of the brakes to stabilize the car's trajectory... much like anyone would have done in the past 50 years of autoracing.

Fangio would have done it the same way... just at slower speeds. with the modern cars, the engines can modulate the power according to diff slip, so its effect is like TC, but not quite as dramatic. shifts are done with the computers sorting out matching reves, ignition retard and advance, diff slip, and now ERS deployment with torque etc..

long and short is most drivers of Ferrari road cars are not going to notice - or even come close to the conditions F-1 cars expereince ... so all this talk is just ... talk.

 

Bravo... the voice of experience and reason.

 

I was really looking for something else, something to give the slightest bit of credence to the proposed theory, but all I saw was the above. Cars are more advanced, drivers have slightly different technique, but the basic laws of physics haven't changed.

 

I know.... if we were taking about a 1958 Ferrari TR then I'd say - sure Hawthorne and Co. probabbly did use engine braking especially at a place like Mulsanne at LeMans... as brakes were not as robust back then... but in 2015 - with a California or any modern F-1 car of the past 20 years... it is negligable at best. most likley engineered out.

just for giggles ... i send an acquaintance of my a note on this... he no longer is in F-1 ... but is currently around alot and gets to drive Redbull's from time to time... no idea when he'll get back to me ...

 

You are quite the synthetic thinker when it comes to this.

First off, let's be clear that F1 technology (in 2011, and today) requires some different types of driver input - in many cases both counter-intuitive and counter-productive to the vast majority of other race cars. Examples - "KERS", "blown diffuser", todays "power units", not to mention the variety of other controls (eg. fuel flow). The only cars likely more complex to operate are the LMP1 cars in WEC. Most of the rest of the racing universe uses LESS tech than the current-gen Ferraris - you might get ABS and TCS, adjustable engine/gearbox maps and some limited suspension adjustments (eg. sway-bars) if you're running GT3 or GTE.

To that point, the "blown diffuser" in F1 cars would want the engine to have revs to help keep downforce high - even when decoupled from the gearbox. When F1 had hyper-sophisticated traction control and launch control (long-banned), drivers would plant the gas and let the software manage it. Said otherwise - it's the difference between flying a Cessna and the Space Shuttle. Same physics, much different design, performance and operating technique.

In the video, what I see is Schumacher going aggressive in first laps, and the overlaps in his brake/throttle are 99% likely due to him left-foot braking (and right foot on throttle). I say that as I've looked at hours of video and data of me (and many other, great drivers) and what the fancy F1 video shows is quite common, particularly during a hectic start, which is both slower than a normal race lap and also ALL about track position vs. perfect driving.

I even brake left-foot in my race car, and my data traces show overlaps. If you're REALLY good, you can keep the brakes on to pin the front end, and roll throttle to get the back to rotate (while it's unloaded- i.e. weight forward) - but I'm not that good and it primarily works only in formula cars.

 

Not according to spirot...

I agree, the DCT of road cars will downshift to prevent stalling. I'm not questioning why road car DCTs automatically downshift even when in manual mode, I'm just pointing out the fact that F1 DCTs can do the same thing.

I don't know the stalling engine speed for an F1 engine but, as spirot just pointed out, even though F1 DCTs are sequential, they are programmable ... so 1st gear can be programmed to engage at a certain engine RPM and vehicle speed to prevent stalling and the rev-match can be programmed to produce an engine speed within the engine's power band.

So if the F1 DCT is programmed properly, the driver can dive into a 1st gear hairpin from any gear at high vehicles speeds, threshold brake for the apex, downshift once and be in 1st gear.

Ego is your term but actually, it does have something to do with the demonstration of the driver's skill (the other term I used)...according to this webpage on the official F1 website "fully automatic transmission systems, and gearbox-related wizardry such as launch control, are illegal - a measure designed to keep costs down and place more emphasis on driver skill."

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I already inserted spirot's comment earlier in this post but since you repeat your assertion that F1 race drivers would not have skipped gears, I will insert spirot's comments (again).

"...plain old balance" - you have also mentioned "balance and fine-tune the corner". Just what do you mean by balance anyway?

 

Interesting. Thanks for posting.

 

I agree, F1 driving is extreme and won't really apply to Fcars on the road.

However, engine braking is usable on the road because it does help to balance the brake bias, hence reduce "weight transfer" and reduce understeer. It helps to make cornering more neutral when you are applying a "fair amount" of braking in a corner.

 

Yes, Schumacher and Button do seem to use corner throttle and braking more than other drivers in that video and the laws of physics don't change. We can also assume is those drivers did that because they felt it useful under those conditions.

FWIW, Schumacher (Mercedes) was 4th, Button (McLaren) 7th. The race was won by Alonso (Ferrari).

 

Yes, that would be interesting. Can you share the contents of your note to your friend with us?

 

Actually I just find it fascinating; "synthesis" helps to make sense of it.

I can also see your plausible point about Schumacher's mass start technique however he does keep it up even after all the cars have strung out along the course. Button's driving was also recorded mid-race and he is very active with the throttle through the corners, even when not alongside other cars, and all the while downshifting. Obviously all the drivers are trying to go as fast as they can around the corners and applying throttle helps but some drivers seem to do this more than the others.

All the same, I appreciate your expert lessons on the comparative housekeeping requirements of disparate racing hardware...

 

Again, back to your original thesis, most recently stated thusly:

Many of us, including me, disagree. Engine braking does not reduce weight transfer.

You've thrown around a lot of tangential stuff, much of which is irrelevant to the engine braking thesis. Gear-skipping is one example.

I'll grant the info that in the manual days, F1 drivers would skip gears during lengthy downshifts. Again, this is completely irrelevant to the engine braking discussion. Here, you're playing with a hypothetical story about programming a DCT to skip gears (skipping many more than drivers actually did "back in the day"). Sure, you could program a DCT to take some sort of input to drop from, say, 5th to 1st while deliberately overalpping the clutches so there's only a single clutch engagement at the end (I assume this is what you mean by "downshifting once", since a DCT gearbox absolutely cannot shift directly from 5th to 1st as an H-pattern box can). They're not programmed to work this way because there's no point whatsoever in working this way.

I think you used "macho", which I translated to "ego". So, again, whatever the reason for certain levels of shift automation being eventually outlawed in F1, what does this particular tangent have to do with the engine braking thesis?

By "balance", I mean what a driver does when tuning maintenance throttle mid-corner. You add a little to increase slip at the rear, thus increasing rotation. Or you trail a little to increase front-end bite. These are very fine fore-aft balance transfers. But, once again, it is not for the purpose of bring in engine braking. I'm not saying the engine braking doesn't happen; of course it does. But it's not the objective.