Term understanding...
03-02-2006, 02:18 PM
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Because my english isn't always helping me especially in technical stuff i have a question:
What's double de-clutching and how is it achieved in an automatic gearbox? I know it can be achived but how?
I think i know the meaning in romanian but i'm not quite sure.
Thanx!
What's double de-clutching and how is it achieved in an automatic gearbox? I know it can be achived but how?
I think i know the meaning in romanian but i'm not quite sure.
Thanx!
03-02-2006, 02:24 PM
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Double clutching refers to a technique used in a car with a manual gearbox, where you are downshifting, and while the transmission is in neutral, with the clutch disengaged, you rev match the engine and transmission, to synchronise them, to minimize wear. Since an automatic transmission doesn't have a clutch (it has a torque converter), double clutching doesn't apply.
03-02-2006, 02:26 PM
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Originally Posted by FastCarFan' post='248840' date='Mar 2 2006, 03:24 PM
Double clutching refers to a technique used in a car with a manual gearbox, where you are downshifting, and while the transmission is in neutral, with the clutch depressed, you rev match the engine and transmission, to synchronise them, to minimize wear. Since an automatic transmission doesn't have a clutch (it has a torque converter), double clutching doesn't apply.
By the way, my understanding was that with modern synchros in manual gearboxes that double-clutching wasn't really necessary. True?
03-02-2006, 02:32 PM
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Originally Posted by FastCarFan' post='248840' date='Mar 2 2006, 06:24 PM
Double clutching refers to a technique used in a car with a manual gearbox, where you are downshifting, and while the transmission is in neutral, with the clutch depressed, you rev match the engine and transmission, to synchronise them, to minimize wear. Since an automatic transmission doesn't have a clutch (it has a torque converter), double clutching doesn't apply.
03-02-2006, 02:50 PM
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Originally Posted by BetterMakeWay' post='248843' date='Mar 2 2006, 03:32 PM
I understand that but watching a top gear episode when they had a race, jeremy in an aston db9 and the other guys in the tgv, he said the most important thing about the db9 is the gearbox. The padels on the steering wheel are attached to an automatic." And it double de-clutches...in an auto!!!" The exact words. That's why i asked! Because i knew the same thing...harder for me tohugh to explain it in english but i knew the same thing. And then i asked how can an automatic double de-clutch?
03-02-2006, 04:15 PM
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You are all partialy right. Double clutching was a technique designed to enable smooth downshifts and prevent gear damage. Double clutching was and is used for downshifting cars with straight cut gears and no syncros. These days all street cars and almost all race cars have syncro transmissions so true double clutching is not required to protect the transmission. However, when driving at the limit of a car it is still neccesary to match the revolutions of the engine to the speed the wheels are turning in order to not upset the balance of the car when you engage the gear. You do this with the heel/toe method as follows.
1.) Begin braking
2.) Depress the clutch with your left foot
3.) While keeping the brake depressed with the toes of you right foot you use the heel of the right foot to depress the throttle (blip) so that the engine RPMs exceed the point you need to match the revs of the wheels. As you release the throttle you also release the clutch.
This results in a down shift that does not upset the car and puts no strain on the transmission.
When done right you will not feel the car speed up or slow down due to releasing the clutch. You will never be a quick driver until you master this technique.
I am always amazed by drivers who slam the car down a gear making lots of noise while using the engine to slow the car down. Engine and transmissions are expensive compared to brakes. Remember, the only reason you downshift is to ensure you are in the proper gear to accelerate after you are done braking.
Here is a link to a video that show Heel and Toe done properly
www.radicalmotorsport.com/gallery/mv_feet.mpg
Enjoy!!!!
1.) Begin braking
2.) Depress the clutch with your left foot
3.) While keeping the brake depressed with the toes of you right foot you use the heel of the right foot to depress the throttle (blip) so that the engine RPMs exceed the point you need to match the revs of the wheels. As you release the throttle you also release the clutch.
This results in a down shift that does not upset the car and puts no strain on the transmission.
When done right you will not feel the car speed up or slow down due to releasing the clutch. You will never be a quick driver until you master this technique.
I am always amazed by drivers who slam the car down a gear making lots of noise while using the engine to slow the car down. Engine and transmissions are expensive compared to brakes. Remember, the only reason you downshift is to ensure you are in the proper gear to accelerate after you are done braking.
Here is a link to a video that show Heel and Toe done properly
www.radicalmotorsport.com/gallery/mv_feet.mpg
Enjoy!!!!
03-02-2006, 04:22 PM
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Forgot, you cannot do this in an auto or steptronic transmission. However the new SMG in the E-60 M5 does match revs on downshifts and it is incredible! I spend a couple hours a week driving one and always smile when it happens. I love it!
03-02-2006, 06:10 PM
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Originally Posted by FastCarFan' post='248840' date='Mar 2 2006, 03:24 PM
Double clutching refers to a technique used in a car with a manual gearbox, where you are downshifting, and while the transmission is in neutral, with the clutch depressed, you rev match the engine and transmission, to synchronise them, to minimize wear.
Ummm just to clearify... did you mean disengaged? Not depressed... when the clutch pedal is UP?
What you just described was just rev matching... not double clutching...
And on the DB9 note... I think it was a SMG type gearbox wasnt it? so thats why he said whatever he said...
Oh and not just the M5 Rev matches... regular cheapie production SMGs rev match too.
Read here...
http://318ti.org/notebook/shifting/index.html
About 1/4 of the way down... theres a section on double clutching and on Rev matching...
03-02-2006, 06:38 PM
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Originally Posted by EBMCS03' post='248955' date='Mar 2 2006, 10:10 PM
Ummm just to clearify... did you mean disengaged? Not depressed... when the clutch pedal is UP?
What you just described was just rev matching... not double clutching...
What you just described was just rev matching... not double clutching...
03-02-2006, 06:49 PM
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Originally Posted by BetterMakeWay' post='248843' date='Mar 2 2006, 06:32 PM
I understand that but watching a top gear episode when they had a race, jeremy in an aston db9 and the other guys in the tgv, he said the most important thing about the db9 is the gearbox. The padels on the steering wheel are attached to an automatic." And it double de-clutches...in an auto!!!" The exact words. That's why i asked! Because i knew the same thing...harder for me tohugh to explain it in english but i knew the same thing. And then i asked how can an automatic double de-clutch?
BTW, we also just say "double clutch" instead of "double de-clutch"