Quite simply Double clutching is a process of matching the speed of your engine to that of your transmission.
How is it done?
Simple.....
1) press the clutch in
2) move the gear selector to neutral
3) let the clutch out
4) push the clutch in
5) move the gear selector to the next gear ( up or down )
Why do you do it?
Well..... it saves the transmission a great deal of stress.... especially when racing.
The purpose of a syncro is to try and match the speed of the main shaft (attached to your clutch) and the speed of the next set of gears your about to engage.
They are not at the same speed.... so this would cause the gears to grind as the mesh together.
The syncro helps this transition by forcefully matching the speeds of the two gears/shafts.
It's kind of like a mini clutch.... kind of hard to explain... there are lots of parts.....hmmm I have an idea.... Wikipedia
Hmmm... the decription is slightly technical... but it explains it better than I could.... too bad they didn't have a diagram
http://en.wikipedia.org/wiki/Manual_tra ... ansmission
look under the section called "Synchromesh"
Double Clutching.... what is it.
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PrecisionBoost
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Double Clutching.... what is it.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
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PrecisionBoost
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So.... how does double clutching help?
Well the reason the two gears/shafts are not at the same speed is because the gear you just came from had the engine at a different RPM level than the next gear your selecting.
When you put the clutch in the engine and transmission can rotate at different speeds.
But if you put it into neutral and very quickly release the clutch the engine and tranny speeds are matched perfectly
Then as you go into the next gear there is no need for syncros since the two shafts are rotating at the same speed.
Hopefully you guys understand the concept.
The idea is to do it very quickly.... basicly at the same speed you currently shift at.
You don't need to do it slow..... it's just a quick "blip" of the clutch pedal as your shifting.
At first.... it will feel awkward..... and very slow.... but once you practice for a few months you will find that you can do it just as quick as you did when you didn't double clutch.
Basicly it requires that your brain learn the pattern.... then you don't have to think about it... you just do it.
In the end your tranny life will be greatly extended.... as syncros are probably the number one killer of manual gearboxes.
Well the reason the two gears/shafts are not at the same speed is because the gear you just came from had the engine at a different RPM level than the next gear your selecting.
When you put the clutch in the engine and transmission can rotate at different speeds.
But if you put it into neutral and very quickly release the clutch the engine and tranny speeds are matched perfectly
Then as you go into the next gear there is no need for syncros since the two shafts are rotating at the same speed.
Hopefully you guys understand the concept.
The idea is to do it very quickly.... basicly at the same speed you currently shift at.
You don't need to do it slow..... it's just a quick "blip" of the clutch pedal as your shifting.
At first.... it will feel awkward..... and very slow.... but once you practice for a few months you will find that you can do it just as quick as you did when you didn't double clutch.
Basicly it requires that your brain learn the pattern.... then you don't have to think about it... you just do it.
In the end your tranny life will be greatly extended.... as syncros are probably the number one killer of manual gearboxes.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
I think that the double clutching sould be divided in two sections. The first as already described is OK for gearing up. But for gearing down you have to speed up engine between steps 3 & 4. In fact you have to expect the speed the engine will have if already engaged at the lower gear ratio.
That's what I have had to do with non synchro army trucks, yeeeeeeeeeeeears ago.
Daniel
That's what I have had to do with non synchro army trucks, yeeeeeeeeeeeears ago.
Daniel
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PrecisionBoost
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I didn't go into rev matching.... but yes.... in many cases it required.
In fact if the speed of both shafts is identical you don't actually need a clutch ( don't try this a home unless you don't care if you grind gears)
I've done clutchless shifting on a number of occasions.... it's just like double clutching....you need to practice.
On an Optra with it's big heavy flywheel it takes forever for the RPM to come down.... so clutchless shifting would be very slow.
But on a race vehicle with an extreemly light flywheel/crankshaft/connecting rod/piston combination the RPM drops extreemly quickly.... so it's possible to rev match going upwards and shift even quicker than you could with a clutch.
On the down shift you need to "blip" the throttle to get the engine RPM equal or just slightly above the expected RPM of the tranny in the next gear down.... that way you can RPM match and shift with or without a clutch and save your syncros.
I do warn you guys not to try the clutchless shifting until your experienced with rev matching between gears..... you must have precise timing to make it work.... or you will grind (and possibly break ) gears.
In fact if the speed of both shafts is identical you don't actually need a clutch ( don't try this a home unless you don't care if you grind gears)
I've done clutchless shifting on a number of occasions.... it's just like double clutching....you need to practice.
On an Optra with it's big heavy flywheel it takes forever for the RPM to come down.... so clutchless shifting would be very slow.
But on a race vehicle with an extreemly light flywheel/crankshaft/connecting rod/piston combination the RPM drops extreemly quickly.... so it's possible to rev match going upwards and shift even quicker than you could with a clutch.
On the down shift you need to "blip" the throttle to get the engine RPM equal or just slightly above the expected RPM of the tranny in the next gear down.... that way you can RPM match and shift with or without a clutch and save your syncros.
I do warn you guys not to try the clutchless shifting until your experienced with rev matching between gears..... you must have precise timing to make it work.... or you will grind (and possibly break ) gears.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
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Turtle_Wax
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I once had a broken clutch and managed to drive it home without any clutch. It's not a nice experience but as long as you can keep the vehicle moving you can change gear. With experience you can judge the speed & RPM for a nice smooth change without any crunch. The hardest part is moving off from standstill as you have to start it up in gear and kangaroo down the road. Luckily I only had to start off once and managed to time it right so I got through all the traffic lights and give way signs without having to completely come to a stop. It wasn't a pleasant journey I can tell you!
Not that impossible. I put in some practise while on a couple of long trips this past week and I am doing pretty well. At first I stopped for too long in between clutch presses but now I shift at about the same speed as before. However, it is not second nature quite yet.
YMMV.
Edited to add:
Thank you for writing this one up. I had heard the term before but did not understand exactly what was going on. I always prefer to hear a why and have stuff explained.
YMMV.
Edited to add:
Thank you for writing this one up. I had heard the term before but did not understand exactly what was going on. I always prefer to hear a why and have stuff explained.
Light without shadow is blindness.