Double Clutching
Safety Car
Joined: Jun 2005
Posts: 3,989
Likes: 5
From: DFW This user does not support or recommend the product or service displayed in the ad to the right
Not so. Imagine you are doing 80mph on the freeway and you are getting ready to take a very tight clover leaf off ramp. Assume the max speed you can maintain on the ramp is 25 - 30 mph. Best gear to exit the ramp is probably second because it puts you dead center in the power band so you can accelerate out of the turn.
Your options are either 1. slow down early before you get to the turn so you wont cause the rev limiter to engage when you go to second gear at 80 mph, or 2. attack the ramp at 80 mph in third or forth gear, maximize braking so that you carry as much energy into the start of the turn for as long as possible, which will bring tire adhesion up to close to 100%, and then double clutch into second at the neck of the ramp as your speed drops to 25-30. Your tires are operating at near 100% adhesion from the braking, and remain at 100% adhesion through the turn (as long as you stop braking and start accelerating to maintain 25-30) and adhesion unwinds from 100% as you accelerate out of the turn.
Double your money back guarantee that there is no quicker way around the corner. (which is why the pros use this technique). If you do it right, you can set up a neutral drift on the car and then you go through the turn without sterring inputs with the front wheels facing straight.
Oh yes, this is the fastest way to get yourself in trouble too. Exceed 100% for an instant, traction falls to near 0%,the wheels stop turnng and the car will start sliding on a tangent that will take you places you dont want to go as in off the road or another lane (and no - anti lock brakes wont prevent the wheels from stopping and sliding - anti lock brakes only work if the tire is operating within the limits of adhesion).
Your options are either 1. slow down early before you get to the turn so you wont cause the rev limiter to engage when you go to second gear at 80 mph, or 2. attack the ramp at 80 mph in third or forth gear, maximize braking so that you carry as much energy into the start of the turn for as long as possible, which will bring tire adhesion up to close to 100%, and then double clutch into second at the neck of the ramp as your speed drops to 25-30. Your tires are operating at near 100% adhesion from the braking, and remain at 100% adhesion through the turn (as long as you stop braking and start accelerating to maintain 25-30) and adhesion unwinds from 100% as you accelerate out of the turn.
Double your money back guarantee that there is no quicker way around the corner. (which is why the pros use this technique). If you do it right, you can set up a neutral drift on the car and then you go through the turn without sterring inputs with the front wheels facing straight.
Oh yes, this is the fastest way to get yourself in trouble too. Exceed 100% for an instant, traction falls to near 0%,the wheels stop turnng and the car will start sliding on a tangent that will take you places you dont want to go as in off the road or another lane (and no - anti lock brakes wont prevent the wheels from stopping and sliding - anti lock brakes only work if the tire is operating within the limits of adhesion).
If you are changing gears while at the limits of adhesion, I see a wall in your future.
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
Its all about control. When you match engine speed to rear wheel speed, you avoid any drag on traction that could cause a loss of adhesion and control in turns. Assume that you are driving a tire at 100% of its capable traction, and when you downshift, you use the rear tires to speed the engine up, the additional traction demand caused by the compression of the engine will exceed the capability of the tire to adhere to the road and then you are relying on the cars traction control to control your turn.
Match the speeds of the engine and tires, there is very little additional demand on the traction capability of the tire when you downshift, and you go fast. 100% traction equals maximum adhesion which equals maximu tire performance. There is no 101% of traction because once the tire loses adhesion, traction falls to nearly 0% very quickly and goodbye to performance.
The pros heal and toe the accelerator and brake so that they can drive hard into a turn, brake with the right foot to bring the traction demand toward the 100% mark, and while braking blip the throttle with the right foot, double clutch with the left foot to a lower gear, and accelerate out of the turn using engine torgue to maintain near 100% traction. This is the fastest way through any turn
Match the speeds of the engine and tires, there is very little additional demand on the traction capability of the tire when you downshift, and you go fast. 100% traction equals maximum adhesion which equals maximu tire performance. There is no 101% of traction because once the tire loses adhesion, traction falls to nearly 0% very quickly and goodbye to performance.
The pros heal and toe the accelerator and brake so that they can drive hard into a turn, brake with the right foot to bring the traction demand toward the 100% mark, and while braking blip the throttle with the right foot, double clutch with the left foot to a lower gear, and accelerate out of the turn using engine torgue to maintain near 100% traction. This is the fastest way through any turn
Also traction doesn't fall to 0%. If you ere in fact silly enough to downshift mid corner on the limit of adhesion the rear tires would slow down, not lock up, for a moment until the engine caught up. I've done it on purpose at autocrosses and active handling catches it every time. That is the only time you should be driving that close to the edge anyways.
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 231
From: SoCal
I'm a lifetime Auto guy going to my first manual when my Z06 arrives soon.....
Who should I be listening to here ...... double clutch or not ??
I do tend to agree C640HP as I have some track experience with my C5 auto........brake straight and down shift (yes, downshifting to 2nd is necessary in an A4) before turn and accelerate all the way thru the turn thus keeping the rear from getting light.
Also......C640HP: that was a cold statement "I see a wall in your future"
(I have seen the tire stacks
)
DH
Who should I be listening to here ...... double clutch or not ??
I do tend to agree C640HP as I have some track experience with my C5 auto........brake straight and down shift (yes, downshifting to 2nd is necessary in an A4) before turn and accelerate all the way thru the turn thus keeping the rear from getting light.
Also......C640HP: that was a cold statement "I see a wall in your future"
(I have seen the tire stacks ) DH
Thread Starter
Intermediate
Joined: Feb 2008
Posts: 48
Likes: 0
From: McKinney Texas
I found this cool video of a racer down shifting using a heel / toe technique.
http://www.youtube.com/watch?v=klMur6TPkrM
This is a cool video also
http://www.youtube.com/watch?v=JcxHi...eature=related
http://www.youtube.com/watch?v=klMur6TPkrM
This is a cool video also
http://www.youtube.com/watch?v=JcxHi...eature=related
Thread Starter
Intermediate
Joined: Feb 2008
Posts: 48
Likes: 0
From: McKinney Texas
CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
I practice double-clutching sometimes but most often I just rev-match. The geometry of the pedals in the C6 makes it hard for me to properly heel/toe. I roll my right foot (brake/gas pedal) to blip the throttle. It took me a little while before I felt secure under extreme braking with just the edge of my foot on the brake pedal but it works pretty well.
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Team Owner
Joined: Feb 2001
Posts: 27,235
Likes: 121
From: Short Hills, NJ
Racer
Joined: Jul 2006
Posts: 380
Likes: 1
From: East Coast NC
Part 3 had some pretty decent/legit cars in it, but it was the dumb cheesy sayings like that, that make it like the rest. When they were sliding around the mountain road really high up that girl was like, "Whenever I'm drifting nothing else matters, I'm free". Well just to let you know on a observation that I made, is all the kids around town here seem pretty free too whenever they run turning lane redlights or "Drift" onto a road. Nothing else seems to matter; not wiping out that mini van with 4 kids and their mom, not hitting all 6 pedestrians on the crosswalk, and not even killing their self by accident......NOTHING, lol
Team Owner
Joined: Feb 2001
Posts: 27,235
Likes: 121
From: Short Hills, NJ
Well just to let you know on a observation that I made, is all the kids around town here seem pretty free too whenever they run turning lane redlights or "Drift" onto a road. Nothing else seems to matter; not wiping out that mini van with 4 kids and their mom, not hitting all 6 pedestrians on the crosswalk, and not even killing their self by accident......NOTHING, lol
The 4th Fast and Furious is coming out next year and it IS going to have most of the characters from the first movie in it.
Burning Brakes
Joined: Sep 2007
Posts: 801
Likes: 2
From: Las Vegas Nevada
St. Jude Donor '10-'11
Granny Shifting not double clutvhing when you should
http://youtube.com/watch?v=tDjo85NeiO0
sorry, this post reminded me of that
http://youtube.com/watch?v=tDjo85NeiO0
sorry, this post reminded me of that
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 231
From: SoCal
I found this cool video of a racer down shifting using a heel / toe technique.
http://www.youtube.com/watch?v=JcxHi...eature=related
http://www.youtube.com/watch?v=JcxHi...eature=related
DH
Last edited by Dirty Howie; Apr 26, 2008 at 06:10 PM.
Racer
Joined: Jul 2006
Posts: 380
Likes: 1
From: East Coast NC
I heard about that. If I lived in Southern California I could have my car in it. There was a place giving out invites, but you are at their beck and call and they have to think your car is Fast and Furious material.
