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Views: 967  ·  Replies: 10 
> Technique and Dynamics Mega Thread, Got a question, ask away!
Spaz
  Posted: Apr 24 2017, 02:58 PM


I just wanna go fast
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Alright, I wish I could take credit for the idea, but alas, I cannot. Meteor brought up to me the idea of a thread to consolidate discussion about vehicle dynamic and driving technique due to the amount of questions regarding it that have popped up recently.

I will do my best to answer any questions that get posted, but as I'm still well inside the learning curve myself, I won't know everything, so anyone with any insight is welcome to contribute to discussion.

So, without further ado, go ahead and ask away!
xiao
Posted: Apr 24 2017, 03:52 PM


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haha ~ this is an awesome idea! Thanks to you & Meteor, Spaz. grin2.gif

I'd also be very interested in hearing how Sideways, Starion, and J' handle the questions directed to you in this thread. Given I know they've spent a good amount of time & thought behind some pretty fast wheels, if not wrenches.

I don't really have any questions yet... so I guess I'll break the ice in the thread to let more of the newbie kids that rarely venture into the Auto Section ask away.

So regarding driving technique and just general overall experience... I am curious about 2 things:

・ Personally, who do you consider a better pilot. A Pro Rally driver or a Pro Track driver, and why? - I have my bias, but I'm interested in hearing your POV on the argument. happy.gif

・ Second, when did you get comfortable driving at a fast speeds? ... or do you still get excited every time you get behind the wheel ~

... that is, I still get nervous whether on a closed course or the *cough* not-closed course ~ when I'm taking turns at 40/50/60 mph plus+ and my heart still wants to explode like if the H-bomb is about to go off in the middle of my chest. I learned to use it to my advantage and started to enjoy the thrill & tachycardia; but I see some drivers on TV that fling around cars like if they're flippin' hotcakes in the kitchen and it baffles me 'cause I find nothing mundane about almost killing yourself, albeit safely ~ laugh.gif

But yeah, do you still get nervous or has the speed just become normal like a seasoned Schumie? laugh.gif
Spaz
  Posted: Apr 25 2017, 04:33 PM


I just wanna go fast
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QUOTE (xiao @ Yesterday, 6:52 PM)
Personally, who do you consider a better pilot. A Pro Rally driver or a Pro Track driver, and why? - I have my bias, but I'm interested in hearing your POV on the argument. happy.gif


I actually love this question. The disciplines stem from the same goal of going as fast as possible under the given circumstances, but the practiced skill sets are quite different, from my understanding. As someone who has never run a car at the limit off-tarmac (save for a few 4-offs and some minor ice "racing") I can only realistically answer with half the requisite knowledge and understanding.

Driving a car at the limit on tarmac relies on the driver being able to hold the tires at their limit of grip and keeping the car at the proper rotational (yaw) angle in relation to the deformation of the tire tread (slip angle) before the tire starts to lose traction. If both of those angles are at 100% of what is physically possible without sacrificing traction, that is 100% of the limit. An ideal driver here has what is referred to as fully developed car control; they are not leaving any unused traction on the table, but they also are not overdriving the car.

Driving a car on gravel, dirt, ice, snow, etc relies on the driver being able to hold the tires in a state of partial traction that exists above the limit of traction, but still inside the bounds of control. It relies less on the lateral (side to side) grip of the tires and more on their forward bite, using them more to push (or pull, or both) the mass of the car around than to actually steer it... That may not make the most sense but hopefully you can piece together what I'm trying to say. These drivers have what is referred to as overdeveloped car control. They lack the minute ability to control a car at the absolute limit of grip, but they can do things with a car that an underdeveloped or fully developed driver cannot as they exceed those limits of traction. Drifting is very similar in this sense as well, where they can sustain a car at beyond the limits of traction for extended periods.

That all said, neither is better than the other. Each will succeed at their own discipline, but lacks in the other. The tarmac driver will lack the brutish driving style required to be fast in rally, but the rally driver will lack the finesse required to be fast on tarmac.

QUOTE (xiao @ Yesterday, 6:52 PM)
Second, when did you get comfortable driving at a fast speeds? ... or do you still get excited every time you get behind the wheel ~

... that is, I still get nervous whether on a closed course or the *cough* not-closed course ~ when I'm taking turns at 40/50/60 mph plus+ and my heart still wants to explode like if the H-bomb is about to go off in the middle of my chest. I learned to use it to my advantage and started to enjoy the thrill & tachycardia; but I see some drivers on TV that fling around cars like if they're flippin' hotcakes in the kitchen and it baffles me 'cause I find nothing mundane about almost killing yourself, albeit safely ~ laugh.gif

But yeah, do you still get nervous or has the speed just become normal like a seasoned Schumie? laugh.gif

Do I get nervous before sessions? Absolutely, it's healthy when undertaking a risky activity to have some level of reservation, and I'm racing a car that'll hit 135+mph on some of the most dangerous tracks in the country. Do I get nervous enough that I get butterflies? Not usually. I did at Ohio a few times as I was stepping up my pace, just due to how dangerous the track is and the fact that I had never practiced it beforehand in a sim, but the last time before that was at Texas Motor Speedway in 2015, which was my first real away race. In Atlanta last August, I jumped in head first and ran fast right from qualifying because I had prepared with close to 8 hours of track time already in Forza, otherwise I'd have been pretty nervous there too. Ultimately I've built a fairly strong trust in the car and in myself so that as long as I step my speed up methodically and don't drive like a dumbass I know I'll come out the other side.

On track though, all that takes a back seat. I've had high adrenaline moments that I've shared videos of, but I try not to let those slow me down if I can help it. Learn and move on is all I can do, and dwelling is dumb and promotes more mistakes, if not also more dangerous ones. Just recover it and finish the lap, and don't make the same mistake again.

On the street, I don't get nervous because I no longer push my car past 6-7/10ths. The car has become so capable that pushing harder than that is downright dangerous. I'm at the track so often that there's little need to push my luck anywhere else.
(Sean)Lau Yu Xuan
Posted: Apr 26 2017, 06:31 AM


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Well I've been wondering this for a while
Usually when it comes to braking, left foot brake could help in reducing the time needed to reach the brake pedals, while it is riskier to use if you needed to shift down quickly(heel to toe shifting for this)
Now, if I changed the clutch pedal to a longer one like the gas pedal, wouldn't I be able to use my left foot to do heel to toe too?
Then again, I'm still waiting for the day I can get my driver's license tongue.gif

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xiao
Posted: Apr 26 2017, 06:39 AM


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QUOTE (Spaz @ Yesterday, 6:33 PM)
These drivers have what is referred to as overdeveloped car control. They lack the minute ability to control a car at the absolute limit of grip, but they can do things with a car that an underdeveloped or fully developed driver cannot as they exceed those limits of traction. Drifting is very similar in this sense as well, where they can sustain a car at beyond the limits of traction for extended periods.

That all said, neither is better than the other. Each will succeed at their own discipline, but lacks in the other. The tarmac driver will lack the brutish driving style required to be fast in rally, but the rally driver will lack the finesse required to be fast on tarmac.

See that's why I love hearing your input on everything man!

I tend to tell people I like rally better than track racing, but I guess it's really a rhetorical question, cause as you mentioned it's like comparing apples & oranges. You can't say one driver's better than the other cause both specialties are delicious depending on what you're feeling like for breakfast. laugh.gif

I've always thought of track drivers as surgeons and rally drivers as acrobats jumping through razors ~ cause funnily enough I've heard of WRC drivers becoming test pilots for F1 teams and vice versa.

QUOTE (Spaz @ Yesterday, 6:33 PM)
...but the last time before that was at Texas Motor Speedway in 2015, which was my first real away race.

And here I thought all the good tracks were down in Florida! w00t2.gif laugh.gif
Meteor
Posted: Apr 26 2017, 08:08 AM


Were you expecting something else?
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QUOTE ((Sean)Lau Yu Xuan @ 57 minutes, 52 seconds ago)
Well I've been wondering this for a while
Usually when it comes to braking, left foot brake could help in reducing the time needed to reach the brake pedals, while it is riskier to use if you needed to shift down quickly(heel to toe shifting for this)
Now, if I changed the clutch pedal to a longer one like the gas pedal, wouldn't I be able to use my left foot to do heel to toe too?
Then again, I'm still waiting for the day I can get my driver's license tongue.gif

There's a rather advanced downshift technique that doesn't use the clutch at all, where you simply shift to neutral, then bring the revs up to where they should be so the gearbox can smoothly enter the gear you're dropping to. That one well known instructional vid from the Skip Barber Racing School teaches this as a way of keeping the car going if the clutch fails. If you really wanted to combine rev-matched downshifts with left foot braking, this'd be a (relatively) more practical way of going about it.
Note, however, that they didn't teach this as a way of going faster; just as a way of getting a damaged car to the pits. That pretty much means that even if you could brake slightly faster this way, the difference ultimately wouldn't matter, either because the difference would be tiny or because it's simply not something you can be consistent with.
As far as slowing down on a straight is concerned, left foot braking isn't as important when you have a clutch pedal and have to downshift before the corner. Even serious drivers like Spaz just brake like normal and then heel-toe to get a smooth entry, because perfect trail-braking into a corner saves much more time than hitting the brakes some milliseconds earlier on the straight. Left foot braking all the time is best reserved for cars that only have two pedals. For fully manual cars, you'll only want to get on the brakes like this if you can stay in the same gear from braking point to corner entry.

Of course, switching from regular braking to left foot braking while entering a corner is something that can be done more easily, and can also have practical uses depending on how your car handles. Suppose you're driving a car where the differential stays open under braking, meaning that as the engine revs down, it has a greater braking effect on the inside wheel(s) than the outside wheel(s) - something that can easily give you lots of oversteer (or worse, a full on lockup). Use of left-foot braking here can help prevent that, as you can easily feed power to the drive wheels and minimize excess slowdown without having to actually step off the brakes. Heel-toe also accomplishes this in somewhat the same manner, but this is a way of doing so for situations where you can't downshift.
That's one way of how left foot braking can help in the corner itself, and I'm sure someone else here can describe one or two other methods.
Spaz
  Posted: Apr 26 2017, 10:46 AM


I just wanna go fast
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QUOTE ((Sean)Lau Yu Xuan @ 3 hours, 33 minutes ago)
Well I've been wondering this for a while
Usually when it comes to braking, left foot brake could help in reducing the time needed to reach the brake pedals, while it is riskier to use if you needed to shift down quickly(heel to toe shifting for this)
Now, if I changed the clutch pedal to a longer one like the gas pedal, wouldn't I be able to use my left foot to do heel to toe too?
Then again, I'm still waiting for the day I can get my driver's license tongue.gif

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Ultimately that won't work, since the clutch pedal has a much larger range of motion than the brake or throttle. The brake pedal, with a decently set up braking system anyway, will only see around half or maybe a bit more of its total travel between disengaged and locked up. I've never had the brake pedal in the Evo literally on the floor. The clutch, however, goes to the floor every shift. There really isn't anything easy you can do to the pedal or pedal assembly to make the two operate with a movement range close enough to allow heel toe with those two pedals. At the end of the day, it's just simpler with your right foot and the gas and brake.

If the minuscule time spent coasting between releasing the accelerator and depressing the brake is that big of an issue, trying to reinvent the wheel is hardly the answer with today's cars; just get something with a dual-clutch gearbox and call it a day.

QUOTE (Meteor @ 1 hour, 56 minutes ago)
There's a rather advanced downshift technique that doesn't use the clutch at all, where you simply shift to neutral, then bring the revs up to where they should be so the gearbox can smoothly enter the gear you're dropping to. That one well known instructional vid from the Skip Barber Racing School teaches this as a way of keeping the car going if the clutch fails. If you really wanted to combine rev-matched downshifts with left foot braking, this'd be a (relatively) more practical way of going about it.
Note, however, that they didn't teach this as a way of going faster; just as a way of getting a damaged car to the pits. That pretty much means that even if you could brake slightly faster this way, the difference ultimately wouldn't matter, either because the difference would be tiny or because it's simply not something you can be consistent with.
As far as slowing down on a straight is concerned, left foot braking isn't as important when you have a clutch pedal and have to downshift before the corner. Even serious drivers like Spaz just brake like normal and then heel-toe to get a smooth entry, because perfect trail-braking into a corner saves much more time than hitting the brakes some milliseconds earlier on the straight. Left foot braking all the time is best reserved for cars that only have two pedals. For fully manual cars, you'll only want to get on the brakes like this if you can stay in the same gear from braking point to corner entry.

Of course, switching from regular braking to left foot braking while entering a corner is something that can be done more easily, and can also have practical uses depending on how your car handles. Suppose you're driving a car where the differential stays open under braking, meaning that as the engine revs down, it has a greater braking effect on the inside wheel(s) than the outside wheel(s) - something that can easily give you lots of oversteer (or worse, a full on lockup). Use of left-foot braking here can help prevent that, as you can easily feed power to the drive wheels and minimize excess slowdown without having to actually step off the brakes. Heel-toe also accomplishes this in somewhat the same manner, but this is a way of doing so for situations where you can't downshift.
That's one way of how left foot braking can help in the corner itself, and I'm sure someone else here can describe one or two other methods.

While doable, clutchless shifting simply is not the best or most efficient way to do things, and is taught in racing schools purely for limping a damaged car, as you noted. The amount of concentration it takes is dangerous to take away from everything else you have going on while you're entering a braking zone and corner while on attack, so it's not a conceivable skill to use while driving at the limit.

That said, left foot braking is a very high level skill. While yes, anyone can use their left foot to press the brake while maintaining some throttle input, but to do so in a manner that makes you faster is incredibly difficult. As a driver, you use your right foot for all the modulation of inputs; brake and accelerator. Your left foot is used to operate the clutch, which outside of starting the car rolling is effectively an on/off switch. Your left foot and leg don't naturally learn the minute muscle motions required for precise modulation like your right leg and foot do, so what you'll most likely find when trying to left foot brake is that your lap times will suffer because you'll be using too much brake. The overwhelming majority of drivers will be best off leaving the skill on the shelf save for maybe one or two situations throughout their career.
(Sean)Lau Yu Xuan
Posted: Apr 30 2017, 08:26 AM


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Wouldn't clutch less shifting grind the gears? Or am I just misunderstanding something? :V

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Meteor
Posted: Apr 30 2017, 09:26 AM


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On modern gearboxes, that entirely depends on if you got the revs to where they should be for the gear you're shifting to.
If you shift to neutral, properly raise the revs to where they should be, and then downshift, the synchros in the gearbox will allow the shifter to smoothly slide into gear.
If you don't properly rev-match, the shifter won't want to slide into gear, and will grind if you try forcing it.
(Sean)Lau Yu Xuan
Posted: May 1 2017, 01:30 AM


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I see, thanks for the info smile.gif

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Spaz
  Posted: May 1 2017, 02:33 PM


I just wanna go fast
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Can confirm that it is indeed possible to do without grinding. Had to limp my Evo VIII 7 miles home one night when the clutch disc hub failed and loosed a spring into the pressure plate and locked the clutch engaged.