Double Clutching Vs. Single Clutching Question
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Double Clutching Vs. Single Clutching Question
Is it necessary to let off the clutch while popping the rev to match the lower gear? That is, instead of clutching to take out of gear, releasing clutch and popping the revs and then clutching again back in gear----can you just engage the clutch, come out of gear--keep the clutch engaged while popping the rev, keep clutch engaged while putting into lower gear.
Sorry if that's confusing.
I'm guessing you're putting a tiny tiny bit of wear on the throw-out bearing but is it really that big a deal?
Sorry if that's confusing.
I'm guessing you're putting a tiny tiny bit of wear on the throw-out bearing but is it really that big a deal?
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Joined: Mar 2015
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Is it necessary to let off the clutch while popping the rev to match the lower gear? That is, instead of clutching to take out of gear, releasing clutch and popping the revs and then clutching again back in gear----can you just engage the clutch, come out of gear--keep the clutch engaged while popping the rev, keep clutch engaged while putting into lower gear.
Sorry if that's confusing.
I'm guessing you're putting a tiny tiny bit of wear on the throw-out bearing but is it really that big a deal?
Sorry if that's confusing.
I'm guessing you're putting a tiny tiny bit of wear on the throw-out bearing but is it really that big a deal?
Instructor
Joined: Jul 2013
Posts: 216
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I've read somewhere, but don't recall where I read it. Double clutching was used for old Porsche transmissions, but it's not needed for modern day transmissions.
Edit: I remembered my source, it's from the book "Ultimate Speed Secrets".
Edit: I remembered my source, it's from the book "Ultimate Speed Secrets".
Last edited by robbieracer; Apr 3, 2015 at 02:51 PM.
Instructor
Joined: Jan 2014
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From: Houston, TX
Wow. Maybe I'm way off the mark here, but maybe you're making this a lot more difficult than it needs to be? Even with my lightweight flywheel, I've never seen the need to worry much about matching revs.
Let off gas, disengage clutch, change gears, engage clutch smoothly while progressively applying gas. Voila.
Let off gas, disengage clutch, change gears, engage clutch smoothly while progressively applying gas. Voila.
Nordschleife Master
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The former will minimize synchro wear (but slower) while the latter is good enough to rev match (but will still create some synchro wear). In either case, the throw out bearing wear is not the concern as it's cheaper and easier to fix compared to the synchros.
Nordschleife Master
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And yes, most here will tell you double clutching is not needed in modern transmissions.
I don't think it's needed either. It's just that you wear the synchros less if you double clutch correctly. Whether you care about that is up to you.
I don't think it's needed either. It's just that you wear the synchros less if you double clutch correctly. Whether you care about that is up to you.
Thread Starter
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I know exactly what it is but I like doing it. It's fun to match the revs and have a really smooth deceleration. Sorry everyone else thinks it's not necessary. BTW, in our DE's it is necessary to demonstrate the skill before progressing beyond intermediate.
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Race Car
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From: Jacksonville, FL Duval County
It makes putting it in the lower gear much easier, even with modern syncros. I worry about the sudden load on the transmission input shaft, but it has so little rotational inertia it's probably fine.
I had to learn on a delivery truck, so I do it for all cars now. Makes for smooth heel toe downshifts when you get it right!
I had to learn on a delivery truck, so I do it for all cars now. Makes for smooth heel toe downshifts when you get it right!
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Instructor
Joined: Jan 2014
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From: Houston, TX
I learned to drive on a manual and most of my cars have been manual, but have never had to do this before. It could easily be my own ignorance though.
Thread Starter
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You've got lots and lots of weekends before they'll ask you to demonstrate proficiency. If you match the revs right you don't even need to engage the clutch. If you don't you grind. I don't risk it!
Banned
Joined: Mar 2010
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From: Chicago
I only do it because I was already used to doing it when driving my '74 BMW. My other reason to do it is to just show off because I have Tubi's but as others stated modern trannys with syncro's don't need to be double clutched.
One situation where it can come in handy is if your slave clutch cylinder starts failing, you can rev match and be able to change gears still. Had to do this once before.
One situation where it can come in handy is if your slave clutch cylinder starts failing, you can rev match and be able to change gears still. Had to do this once before.
