Double Clutching? How many definitions are there?????
11-25-2002, 09:14 PM
#1
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Double Clutching? How many definitions are there?????
ive heard so many definitions of it, but i want the real one..
here are some...
1. the kind of clutching u need to do when driving a tractor trailer: while in gear, engage the clutch, shift into neutral, release the clutch, engage again & into the next gear...
2. your driving and say you are in 2nd, you engage the clutch, rev it up, shift and disengage clutch
3. the fast and furious definition, i wont even discuss it...
4. your driving, and you quickly hit the clutch twice...
i thought #1 wuz the real one, or is it sumthn else?!
here are some...
1. the kind of clutching u need to do when driving a tractor trailer: while in gear, engage the clutch, shift into neutral, release the clutch, engage again & into the next gear...
2. your driving and say you are in 2nd, you engage the clutch, rev it up, shift and disengage clutch
3. the fast and furious definition, i wont even discuss it...
4. your driving, and you quickly hit the clutch twice...
i thought #1 wuz the real one, or is it sumthn else?!
11-25-2002, 10:59 PM
#3
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i have always heard of it being defintion #1
you push in clutch, put it in neutral, disengage clutch, blip the accelerator, engage clutch, put into gear, diengage clutch.
this is done to get the gears goin at the same speeds.
as arcanum said, modern day synchros take care of this and you don't have to do it on our cars
you push in clutch, put it in neutral, disengage clutch, blip the accelerator, engage clutch, put into gear, diengage clutch.
this is done to get the gears goin at the same speeds.
as arcanum said, modern day synchros take care of this and you don't have to do it on our cars
Last edited by ish; 11-25-2002 at 11:03 PM.
11-25-2002, 11:02 PM
#4
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oh yeah, and IIRC, double clutching is mainly just used for down shifting. it can still be done on current cars to extend the life of the tranny some, i think.
11-26-2002, 12:14 AM
#8
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ok, here goes... I would describe it as matching 3 separate parts in drivetrain: engine, layshaft (inside tranny), and drive shaft to wheels.
during downshifting you step on the clutch but all 3 are spinning at similar speed.(still in same gear) Now you put it in neutral and let up the clutch, and by engaging clutch you have the engine and layshaft spinning at same speed. you blip and speed up the layshaft. now you can downshift since layshaft matches closer to lower gear (higher gear ratio). you step on the clutch to downshift and blip second time to match engine and the rest (layshaft and driveshaft).
basically, double clutch involves extra blip to spin up the layshaft to match lower gear when shifting with no syncros.
hope this helps.
during downshifting you step on the clutch but all 3 are spinning at similar speed.(still in same gear) Now you put it in neutral and let up the clutch, and by engaging clutch you have the engine and layshaft spinning at same speed. you blip and speed up the layshaft. now you can downshift since layshaft matches closer to lower gear (higher gear ratio). you step on the clutch to downshift and blip second time to match engine and the rest (layshaft and driveshaft).
basically, double clutch involves extra blip to spin up the layshaft to match lower gear when shifting with no syncros.
hope this helps.
11-26-2002, 12:22 AM
#9
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Join Date: Nov 2002
Location: colorado
Posts: 79
only one definition
Number 1 is correct.
Number 2 is rev matching, usually associated with down shifting, which you may have to do while double clutching if your speed changes drastically before you can make the second part of the shift. On a car with poor syncros you may have to double clutch and rev match to shift up on widely space gears.
Why you do it?
It makes life easier for the syncros.
The instant you push in the clutch the main shaft of transmission is disconnected from the engine. When you kick it out of gear, the drag from all the gear oil and such starts to slow the shafts and gears down quickly. As described in the beginning it is nearly manditory on older truck transmissions because they have really clunky shifters and are very hard to shift quickly. The syncros also have to spin up much heavier gears in the truck transmissions.
By quickly releasing the clutch for a fraction of a second when you are in neutral it keeps the main shaft spinning at nearly the same speed it was before the shift and the syncros have less work to do to get gear speeds matched up.
If you have the video of the movie Bullit, listen to the engine note on Steve McQueens Mustang during the last part of the chase scene. You can clearly hear him double clutching each up shift.
Larry
Number 2 is rev matching, usually associated with down shifting, which you may have to do while double clutching if your speed changes drastically before you can make the second part of the shift. On a car with poor syncros you may have to double clutch and rev match to shift up on widely space gears.
Why you do it?
It makes life easier for the syncros.
The instant you push in the clutch the main shaft of transmission is disconnected from the engine. When you kick it out of gear, the drag from all the gear oil and such starts to slow the shafts and gears down quickly. As described in the beginning it is nearly manditory on older truck transmissions because they have really clunky shifters and are very hard to shift quickly. The syncros also have to spin up much heavier gears in the truck transmissions.
By quickly releasing the clutch for a fraction of a second when you are in neutral it keeps the main shaft spinning at nearly the same speed it was before the shift and the syncros have less work to do to get gear speeds matched up.
If you have the video of the movie Bullit, listen to the engine note on Steve McQueens Mustang during the last part of the chase scene. You can clearly hear him double clutching each up shift.
Larry
Last edited by hotrod; 11-26-2002 at 12:24 AM.
11-26-2002, 10:40 AM
#10
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It's been a while since I've seen Bullitt, but you can't hear double clutching unless the clutch is really squeaky. 
I double clutch all the time, and it's now a habit. It's so satisfying when you pull off a rev matched heel `n toe double clutched downshift and the gear lever just glides into gear with no effort.
I double clutch all the time, and it's now a habit. It's so satisfying when you pull off a rev matched heel `n toe double clutched downshift and the gear lever just glides into gear with no effort.
11-26-2002, 01:15 PM
#12
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Fast & Furious is not possible. You don't double clutch an upshift.
To do it, say from 3rd to 2nd.
You're cruinsing in 3rd.
Put your foot on the clutch and take it out of 3rd and into Neutral.
Rev to what the RPM's will be when you will be in second.
Put it into 2nd gear, and let out the clutch.
If you did this correctly, you won't feel the car going into 2nd, it should be seemless.
To do it, say from 3rd to 2nd.
You're cruinsing in 3rd.
Put your foot on the clutch and take it out of 3rd and into Neutral.
Rev to what the RPM's will be when you will be in second.
Put it into 2nd gear, and let out the clutch.
If you did this correctly, you won't feel the car going into 2nd, it should be seemless.
Last edited by Lobster Man; 11-26-2002 at 01:17 PM.
11-26-2002, 04:05 PM
#14
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Originally posted by Lobster Man
Fast & Furious is not possible. You don't double clutch an upshift.
To do it, say from 3rd to 2nd.
You're cruinsing in 3rd.
Put your foot on the clutch and take it out of 3rd and into Neutral.
Rev to what the RPM's will be when you will be in second.
Put it into 2nd gear, and let out the clutch.
If you did this correctly, you won't feel the car going into 2nd, it should be seemless.
Fast & Furious is not possible. You don't double clutch an upshift.
To do it, say from 3rd to 2nd.
You're cruinsing in 3rd.
Put your foot on the clutch and take it out of 3rd and into Neutral.
Rev to what the RPM's will be when you will be in second.
Put it into 2nd gear, and let out the clutch.
If you did this correctly, you won't feel the car going into 2nd, it should be seemless.
11-26-2002, 04:40 PM
#15
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Join Date: Nov 2002
Location: OC, CA
Posts: 181
Car Info: 02 WRX
Originally posted by imprezton
I rev while clutch is depressed, shifter in transit. Seems to me it'd waste time stalling in neutral to match revs.
I rev while clutch is depressed, shifter in transit. Seems to me it'd waste time stalling in neutral to match revs.
if you dont, you have to blip in neutral to match engine and layshaft in tranny before you can downshift.
here's good info: http://www.howstuffworks.com/transmission2.htm