[Theruleslawyer]

Originally Posted by Efthreeoh

What does "done it on a track mean"? Avoiding a deer at 200 KPH, or just getting on the brakes hard at 200 KPH driving your line through the track? All my BMWs just squat down on the suspension and stop, it doesn't upset the attitude of the car.

Stopping at max brake force. I mean there are deer at the track, but I haven't had to avoid one yet. You wanted to know what a DCT does with a max braking event. I've done that over and over again.

Ripping down the gears at max brake force without upsetting the car is much harders to do on a manual, not just braking. I wouldn't attempt it either. Both feet in, especially if you're not used to doing it.

Did you expect a DCT to do something weird?

[jmg]

Originally Posted by BGM-M3COMP

It's only frustrating when you watch people run around the argument at hand just to have a say in the discussion. The shit is too easy to read.

It's simple.

People said it's ONLY fun to drive a manual. FALSE.

You can find extreme enjoyment in ANY CAR, REGARDLESS of the trans. Which is the original point before everyone got on their period thinking some people are bashing manual driving.

Moral of the story. No one gives a shit what anyone prefers. You want roll up windows in your car too that's fine.

But the fact is, anyone can find enjoyment, AND HAVE FUN, in both manual AND AUTOMATIC CARS.

Agreed, I had a lot of fun in my old Subaru Forester with a dog-slow engine, mid-tier build quality, and only passable AWD for off-roading. Crossed some rivers, drove to some very cool places...

People forget that the vehicle is a tool, and it's the driver that really matters. I never bought into the gate keeping of manual transmissions. I agree they should be saved, but it really is making the best of what you have.

[jmg]

Originally Posted by Efthreeoh

So what does a DCT do in auto mode when you are hauling ass on a back road in the woods at 100 KPH and a deer comes running out of the woods and you drop anchor with full, instant antilock?

I know what a real manual transmission does. Both feet in, torque instantly dies and vastly improves braking distance. I've hit 5 deer in the past 14 years and 500,000 miles, but I've avoided several hundred others...

I don't have a skin in this game, but my M3 CS DCT set to level 3 downshifts for you, and very smoothly I might add, but it's less to help in braking, and more to set you up to accelerate out. One thing it doesn't do is send torque to the wheels to impede braking.

Originally Posted by Theruleslawyer

I've done it repeatedly at over 200kph on a track. You just blip down the gears as you decel. It doesn't upset the car like you'd probably do with a manual. If you go below speed for a gear it will downshift for you even in manual mode. If you freaked out and did nothing it would end up in 1 with the clutch disengaged.

The DCT in my F80 and the M tuned ZF8 in my G82 are super smooth downshifting. You are right, there is very little to upset the car during hard braking.

Originally Posted by Efthreeoh

What does "done it on a track mean"? Avoiding a deer at 200 KPH, or just getting on the brakes hard at 200 KPH driving your line through the track? All my BMWs just squat down on the suspension and stop, it doesn't upset the attitude of the car.

You probably already know this, but braking on the track is very different than braking in the street. On the track, more advanced drivers don't want to engage ABS. They "threshold brake" which is just enough maximum braking to just before the point where ABS would engauge. I've heard several rationale behind this, the most common being that you an outperform all but the most sophisticated high-performance ABS systems with threshold braking.

On the track, we also practice trail-braking. To put it simply, hard on brakes, then bleed off as you approach the apex. This is mainly done to shift weight from front to rear as we corner. With weight transferring on the front at the beginning of the corner, then shifting to the rear as we apex and begin to apply throttle, ideally with the weight now being on the rear powered wheels. This is where smoothness plays a roll. You want to be in the correct gear as you are lifting off the brakes and start to apply power. This means downshifting as you brake. In a MT, that requires heel-toe so that the car doesn't get upset when most of the weight is on the front tires, and you are beginning to turn. Upsetting the car can be disastrous as you are just transitioning from threshold braking to turning. A disruption can shift the weight to the front just as you are in the middle of transitioning the weight to the rear. All this is happening within hundreds of a second, so when you pull it off in an MT, it's very satisfying, but it's also very difficult, and difficult to reproduce with accuracy and precision lap after lap after lap.

On the street, we do the complete opposite. Emergency braking is almost always full on ABS so that the car doesn't lock the tires and negate steering. In non-emergency braking, we also do the opposite of trail braking. Soft brakes first, then gradually apply more pressure as the car comes to a stop.

In a nutshell, on the street, you aren't trying transition into a corner immediately after hard braking, you simply want to keep on the brakes and stop the car. That's the difference, and technically, why the DCT is more suited for the track than the MT because of how smooth and fast it is for this transition. The same could be said for the M-tuned ZF8.

[shawnhayes]

Originally Posted by freakystyly

It's a bag of worms, like this thread.

There's BMWs SMG which was basically the early DCTs (computer controlled with paddles). I want to say E46 and E60 had the SMG in their Ms? Then there's motorcycles, and race cars which have a clutch pedal/handlebar but don't need to use it beyond first gear... think up/down only not H pattern. Pretty sure they are disticnt with their loud whine if you ever watch youtube vids with a sequential.

Gear whine has as much to do with gear cut as whether or not its a sequential... Most of the loud whines you hear on youtube is because of straight cut sequential shift gearboxes.

https://cartreatments.com/straight-c...at%20advantage.

Reverse gears in most manual gearboxes are straight cut. That's the reason most cars have gear whine when reversing.

Shawn

[BGM-M3COMP]

Originally Posted by jmg

I don't have a skin in this game, but my M3 CS DCT set to level 3 downshifts for you, and very smoothly I might add, but it's less to help in braking, and more to set you up to accelerate out. One thing it doesn't do is send torque to the wheels to impede braking.



The DCT in my F80 and the M tuned ZF8 in my G82 are super smooth downshifting. You are right, there is very little to upset the car during hard braking.



You probably already know this, but braking on the track is very different than braking in the street. On the track, more advanced drivers don't want to engage ABS. They "threshold brake" which is just enough maximum braking to just before the point where ABS would engauge. I've heard several rationale behind this, the most common being that you an outperform all but the most sophisticated high-performance ABS systems with threshold braking.

On the track, we also practice trail-braking. To put it simply, hard on brakes, then bleed off as you approach the apex. This is mainly done to shift weight from front to rear as we corner. With weight transferring on the front at the beginning of the corner, then shifting to the rear as we apex and begin to apply throttle, ideally with the weight now being on the rear powered wheels. This is where smoothness plays a roll. You want to be in the correct gear as you are lifting off the brakes and start to apply power. This means downshifting as you brake. In a MT, that requires heel-toe so that the car doesn't get upset when most of the weight is on the front tires, and you are beginning to turn. Upsetting the car can be disastrous as you are just transitioning from threshold braking to turning. A disruption can shift the weight to the front just as you are in the middle of transitioning the weight to the rear. All this is happening within hundreds of a second, so when you pull it off in an MT, it's very satisfying, but it's also very difficult, and difficult to reproduce with accuracy and precision lap after lap after lap.

On the street, we do the complete opposite. Emergency braking is almost always full on ABS so that the car doesn't lock the tires and negate steering. In non-emergency braking, we also do the opposite of trail braking. Soft brakes first, then gradually apply more pressure as the car comes to a stop.

In a nutshell, on the street, you aren't trying transition into a corner immediately after hard braking, you simply want to keep on the brakes and stop the car. That's the difference, and technically, why the DCT is more suited for the track than the MT because of how smooth and fast it is for this transition. The same could be said for the M-tuned ZF8.

Exactly. Keep preaching.

[jmg]

Originally Posted by Efthreeoh

I get it, some of you guys drive on tracks. I specifically asked about braking at antilock for an unanticipated event like a deer running out from the woods. Add in the 10 minutes at dawn and dusk when they dissappear from the visible light spectrum and it is even worse.

I only answered because you specifically asked about what is meant by braking on the track. Tracking is a hobby that forces us to study driving dynamics beyond the normal public road driver.
As far as what is better, manual or auto/dct for emergency ABS braking? I doubt one has any advantage over the other besides weight.

[jmg]

Originally Posted by Efthreeoh

The fastest way to stop a car is remove engine torque and apply maximum brake torque. The best way to drop engine torque is to instantly find neutral, which is just a millisecond of a clutch pedal push away.

If you are braking hard enough to engage ABS, the small amount of power to the wheels in an automatic transmission equipped vehicle is inconsequential since the ABS system is already cutting off the brakes intermittently. The reason we "threshold brake" on the track is because it is the maximum amount of brakes before ABS kicks in (which is also the point where they would lock if ABS weren't equipped).

So in reality, maximum force to stop the wheel from turning is not needed, or even necessary. It's actually the point right before lock. So really, the added power to the wheels from an automatic would simply factor into the amount of braking before lock, theoretically requiring a tiny bit more braking, BUT ultimately still LESS than full braking.

Originally Posted by Efthreeoh

In my view a DCT is a manual transmission that has to waste time downshifting. In my experience I prefer to have neutral at my foot.

Enjoy the show...

Engine braking does not affect emergency stopping distance.

[G80indy]

It's fun to only drive a manual

😏

[Fined]

Had to get the 6MT for my M2. Three years later.. meh. It's not a particularly great manual box and the DCT would've been a better way to go.

[Theruleslawyer]

Originally Posted by Efthreeoh

Enough of the track crap; its a practiced and controlled driving environment. I get it, you guys who drive track think you know more about driving and can control a car better than those who don't. I know all about threshold braking since I've been driving some 15 years BEFORE antilock braking systems became common place in automobiles. They actually taught threshold braking in driver's ed (imagine that). The cars of my late teens still had drum brakes, mostly on the rear; and throw bias-ply tires into the mix - LOL. So thanks for the lesson I don't need.

Again, driving on a track and trying to find and maintain threshold braking is completely different than trying to miss a moving deer that has been spooked and has run into your path. Engine power, even if you consider it engine braking while the transmission is dropping gears is still adding powered forward motion the the car that the brakes have to dissapate. When trying to miss a deer running across your front end you literally need to take every inch possible out of the distance your car is traveling. That's why antilock was introduced to automobiles because under varying road conditions and equipment condition, in panic situations, engaging antilock stops a car in a shorter and in a more controlled manner.

Abs does not reduce stopping distance. It brakes close to the threshold more reliably than you can in most circumstances.

If you are engaging ABS you have enough brake torque to overcome your max braking grip. (Usually by a substantial amount at normal highway speeds).

Automatic cars also have no issue engaging ABS. Therefore they they also have enough brake torque to exceed max braking grip.

Any difference in distance is weight, balance, and mostly noise. So let's repeat. If you can engage ABS what you are doing with the engine doesn't mean squat.

Im not sure where this idea of the drag of the engine makes a difference comes from. It sounds like lore that started back when 4 wheel drum brakes were a thing and got passed along without question. Or maybe it was a misunderstanding of being told both feet in on emergency braking which is valid, but someone pulled this out of their butt when asked why?

[Theruleslawyer]

Originally Posted by Efthreeoh

Jesus christ, your first sentence contradicts itself. ABS more reliably than the driver can decreases stopping distance exactly because it can apply near threshold braking while preventing wheel lock, thus a skid where the tire loses grip on the road and slides, which increases braking distance. When the driver is in elevated awareness situation of trying to avoid a deer, trying to achieve threshold braking is near impossible and increases the distance he is trying to stop in (which is where the deer is standing or running). ABS compensates for all kinds of variables like uneven tire wear, tire air pressure, brake component conditions, brake component termperature, road surface friction, driver fatigue, etc. which is all the shit the driver has to overcome to achieve threshold braking in a few hundred milliseconds. Threshold braking is available only to the tire with the lowest grip and hardware condition (i.e. the wheel with the best chance to not lock) to prevent lock up. The driver has no time to try and find threshold braking when a deer is 170 feet away and the car is traveling at 60 MPH. ABS provides maximum brake force at each tire contact patch. Threshold braking allows for maximum brake force at the one wheel that has the lowest threshold of lock up; the other three brakes may not be providing their individual maximum braking force

You guys keep looking at minimum stopping distance in the perfect world of a driving vacuum. I'm discussing a real world situation where an animal is suddenly and unexpectedly in your path and there are 50 variables at play trying to avoid hitting it. Taking engine torque out as one variable may just give you the 1/4 inch you need brush the hair on the deer's ass vs. implanting it into your left headlight.

All i can say is you clearly have no idea how abs or brakes in general work.

[Theruleslawyer]

Originally Posted by Efthreeoh

Lol. Right. I just make shit up. Lol.

Correct!

[BGM-M3COMP]

Originally Posted by Theruleslawyer

All i can say is you clearly have no idea how abs or brakes in general work.

And to think we got to this point all because manual purists got offended about people who have/can have fun and enjoyment in an auto car lmaoooo

[IsleOfMs]

Originally Posted by Efthreeoh

Jesus christ, your first sentence contradicts itself. ABS more reliably than the driver can decreases stopping distance exactly because it can apply near threshold braking while preventing wheel lock, thus a skid where the tire loses grip on the road and slides, which increases braking distance.

Nope. The purpose of ABS is to help the driver maintain control, not to have shorter stopping distances. ABS can outperform a novice driver (99% of people on the road?) but it is not designed nor intended to achieve the best possible performance. Again, it's most concerned with maintaining control of the vehicle. It achieves its primary function by erring on the side of safety.

Every time ABS releases the brakes (one of the pumps) you are less efficient at slowing down.

The best way to feel the difference is to engage the ABS and when you feel the vibrations in the pedal, modulate the pedal just enough so that the vibrations stop. Eg, don't hold the brake all the way in but don't release it entirely either. Just lift barely enough so that the vibrations (the ABS) stops.

In this case, you'll be using the maximum amount of braking that never causes a lockup so ABS doesn't intervene. You'll be amazed by how much more braking force you feel as you reach this pre-ABS point. (in this case, "braking force" means tires on road, not foot on pedal). Basically, you'll notice a dramatic increase in the stopping power of your car.

[jmg]

Originally Posted by Efthreeoh

Jesus christ, your first sentence contradicts itself. ABS more reliably than the driver can decreases stopping distance exactly because it can apply near threshold braking while preventing wheel lock, thus a skid where the tire loses grip on the road and slides, which increases braking distance. When the driver is in elevated awareness situation of trying to avoid a deer, trying to achieve threshold braking is near impossible and increases the distance he is trying to stop in (which is where the deer is standing or running). ABS compensates for all kinds of variables like uneven tire wear, tire air pressure, brake component conditions, brake component termperature, road surface friction, driver fatigue, etc. which is all the shit the driver has to overcome to achieve threshold braking in a few hundred milliseconds. Threshold braking is available only to the tire with the lowest grip and hardware condition (i.e. the wheel with the best chance to not lock) to prevent lock up. The driver has no time to try and find threshold braking when a deer is 170 feet away and the car is traveling at 60 MPH. ABS provides maximum brake force at each tire contact patch. Threshold braking allows for maximum brake force at the one wheel that has the lowest threshold of lock up; the other three brakes may not be providing their individual maximum braking force

You guys keep looking at minimum stopping distance in the perfect world of a driving vacuum. I'm discussing a real world situation where an animal is suddenly and unexpectedly in your path and there are 50 variables at play trying to avoid hitting it. Taking engine torque out as one variable may just give you the 1/4 inch you need brush the hair on the deer's ass vs. implanting it into your left headlight.

I have never insinuated that ABS is bad in emergency braking. I only addressed your argument that a manual transmission car can brake better than an auto because of the torque that is sent to the wheels even while braking with an automatic. Again, this is moot if you are braking hard enough to engage ABS because you have already applied braking beyond the capabilities of your tires.

Originally Posted by Efthreeoh

ABS provides maximum brake force at each tire contact patch. Threshold braking allows for maximum brake force at the one wheel that has the lowest threshold of lock up; the other three brakes may not be providing their individual maximum braking force

Actually, ABS does not provide maximum brake force. It provides improved braking capability in emergency situations and is actually closer to REDUCING braking force. It allows for the tires to dissipate kinetic energy by effectively CUTTING brake pressure enough to allow the tires to match speed with the road it is in contact with to regain grip and use that grip to stop the car. If the wheels are locked, they are less effective at dissipating kinetic energy.

All this happens very very fast, intermittently. It also allows for the driver to have more control since locked tires cannot steer the vehicles. All the road sees is a contact patch sliding across the surface. When ABS releases the lock by pumping the brakes intermittently, this allows the wheels to roll and "catch-up" with the road, and effectively return some control.


Threshold braking still has a shorter braking distance in most cases, but you are right, in an emergency situation, it would be difficult to threshold brake unless you've done it thousands of times. And yes, if you track, you start to do this instinctively. I literally threshold brake multiple times a lap and I've done hundreds and hundreds of laps. Not to long ago I had to emergency brake with my family in the car, and instinct kicked in and I didn't engage ABS. My wife literally was in shock how fast we stopped. Everything in the car was thrown to the front, and we were shaken, but threshold braking works. In 99.9% of cases for everyone else though, just use ABS.

[jmg]

Originally Posted by Efthreeoh

The point of me pulling the old man/life-long car enthusiast card is to explain that I "grew up" driving non-ABS cars and was taught threshold braking in driver's ed when I was 16. I know all about proper braking techniques and am one of the experienced drivers that with the intro of ABS, hated the pedal pulse and noise because it was antithetical to who was taught to use brakes. My first ABS car was my 1989 E30.

I'm not as old as you, but my first 2 cars, MK2 GTI and BMW E21, didn't have ABS either, so I get what you are saying, but remember, I also said this:

Originally Posted by jmg

You probably already know this, but braking on the track is very different than braking in the street....

So no way did I insinuate that you were ignorant of what threshold braking is. Only in how the physics behind it relates to how the engine torque in an automatic doesn't reduce braking distance once you have engaged ABS.

Originally Posted by Efthreeoh

But my original question about what the DCT does regarding engine torque was in an emergency braking situation on a normal street in a normal car and not in a track environment.

Again...

Originally Posted by jmg

I only answered because you specifically asked about what is meant by braking on the track.

...and track environment or not, the engine torque in an automatic does not reduce braking distance when engaging ABS.

Originally Posted by Efthreeoh

It's great to talk theoretical application of threshold braking, but in reality relying on ABS to prevent from hitting a deer that has surprised the driver is the best option.

Yes, I've indicated a few times that I agree with this sentiment.

[shawnhayes]

Originally Posted by jmg

Threshold braking still has a shorter braking distance in most cases, but you are right, in an emergency situation, it would be difficult to threshold brake unless you've done it thousands of times. And yes, if you track, you start to do this instinctively. I literally threshold brake multiple times a lap and I've done hundreds and hundreds of laps. Not to long ago I had to emergency brake with my family in the car, and instinct kicked in and I didn't engage ABS. My wife literally was in shock how fast we stopped. Everything in the car was thrown to the front, and we were shaken, but threshold braking works. In 99.9% of cases for everyone else though, just use ABS.

Everybody says they can.

Everybody THINKS they can.

Everybody THINKS they have.

When we objectively test....NOPE...

Shawn

[jmg]

Originally Posted by shawnhayes

Everybody says they can.

Everybody THINKS they can.

Everybody THINKS they have.

When we objectively test....NOPE...

Shawn

That's actually pretty surprising given Scott is a professional. I managed faster times threshold braking in a course that ends with a stop box over abs braking, and I am no professional. Maybe there are other factors we aren't considering:


-Unless you are using a stop box in an autocross type course, you aren't coming to a complete stop. Perhaps the trade-off of reduced braking distance is worth the pedal feel for brake-throttle transition during cornering on the track, reducing lap times.

-Did they let the brakes cool between runs? Braking distance is indeed increased as brake temps go up.

-Did they let the tires cool between runs? Overheated tires and worn tires also increase brake distance.

-I'd also be interested to see how well ABS adapts to overheated brakes and tires. They should have immediately done a few more ABS trials after Scott's non-ABS trials to match conditions better

-They should have done runs with ABS enabled for Scott, but allowed him to threshold brake. Perhaps manually threshold braking, while still allowing the ABS to kick in to account for human error is better than full ABS or full threshold brake? The best of both worlds?



Of course, a track environment is very different than street environment, so I still agree ABS is best for emergency braking on pubic roads.

[shawnhayes]

Originally Posted by jmg

That's actually pretty surprising given Scott is a professional. I managed faster times threshold braking in a course that ends with a stop box over abs braking, and I am no professional. Maybe there are other factors we aren't considering:

Sounds like a YouTube opportunity. Because the experts say you can't. I'd like to see somebody prove them wrong.

Because as you point out, the physics say you CAN, if you can hold the perfect braking pressure right before the wheel locks.

Shawn

[shawnhayes]

Originally Posted by Efthreeoh

Lol. The professional race driver said EXACTLY what I wrote a few posts ago, that the best threshold braking distance is dependent upon the tire with the least grip and locks first. He said without the brake bias that ABS provides its not possible get all 4 tires at threshold braking.

Thanks Shawn for posting the video.

Drops mic....

I HAVE seen abs beaten on gravel and snow. It was the early 1990's, and either Car and Driver or Motor Trend did it with Subaru's.

But it was MOSTLY because the ABS had inconsistent stopping distances as well. The human did an average lower than the ABS. But the shortest stop was still ABS, just the human averaged shorter.

But that was 30 years ago. And they didn't have video.

And Bosch has come up with MUCH better 2 and 4 channel ABS units in the meantime.

Shawn

[jmg]

Originally Posted by Efthreeoh

Lol. The professional race driver said EXACTLY what I wrote a few posts ago, that the best threshold braking distance is dependent upon the tire with the least grip and locks first. He said without the brake bias that ABS provides its not possible get all 4 tires at threshold braking.

Drops mic....

Again, I never really had a big problem with ABS, it was this claim I was disputing:

Originally Posted by Efthreeoh

I know what a real manual transmission does. Both feet in, torque instantly dies and vastly improves braking distance. I've hit 5 deer in the past 14 years and 500,000 miles, but I've avoided several hundred others...

Not sure how this devolved into a ABS vs Threshold debate.

Regardless if anyone can outperform ABS or not, your claim that torque from an automatic increases emergency braking distance when ABS is engaged is incorrect. Not really a "mic drop" moment if we are sticking to the subject.

[shawnhayes]

Originally Posted by Efthreeoh

And some lawyer on here said I clearly have no idea how ABS or brakes work...

Ahuh, right.

Lol.

Don't be butthurt. People lose "the social touch" on the keyboard. It's not personal. Its the internets.

Shawn