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?

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sorry for the joke but this post feels like somebody who just rewatched fast and furious... as fun as those movies are, please don't use them as reference material for how to drive a car...

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".

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.

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.

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 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.

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!

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I've not been to a DE, so that'll be a new one for me when I go. 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.

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!

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.

Double Clutching and Heal-Toe are two different things

I do it (DD) to preserve my synchros and open up my Fister cans

Heel-toe and trail braking are a much better use of your feet than double-clutching. Doesn't the blip during heel-toe accomplish much the same re: synchros?

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I suck at it and need to practice it more while DD'ing.

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Yup.

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Only if you double clutch at the same time. No double clutch, no saving on synchros.

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Correct. Double Clutching has absolutely nothing to do with the brake pedal.

I'm crystal clear that modern cars shift without the need to double clutch or heal to toe but thanks for explaining that to me. Heal to toe is what I was describing as an alternative to double clutching and if it was cool to leave the clutched engaged vs in and out. Try it

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You must not drive very hard. I mean, if I'm coming into a turn hot, diving onto the brakes, then I want the clutch out as quickly as possible once the downshift is done. Your method has you still trying to slowly let out the clutch midway through the turn, not to mention possibly upsetting the balance of the car as you use the clutch to spin up the motor.

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While a heel toe blip allows a faster gear shift that doesn't mean that letting the clutch out slowly and smoothly instead will result in riding the clutch through the turn. Both methods work in different ways and neither is inherently better in all situations.

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I disagree. In general, you want moments without control to be minimized. When you have the clutch in, you have less control. Its inherently better then to match revs on downshifts because you're off the clutch much quicker and you're also not dealing with the compression braking. Use the brakes to slow the car, match revs on the downshifts, and then you're set up for the corner.

There are tons of instructors who disagree with you. Also, being off the clutch and not dealing with compression braking couldn't be more oppositely opposed. But I don't care enough to continue so you are absolutely correct. Letting the clutch out slowly gives baby Jesus aids and should never happen.

So the question now is...what would baby Jesus do?

Heal and toeing is (usually) for aggressive driving. Double clutching begins in the days of straight cut gears without syncros...sometimes called "crash boxes." I still enjoy double clutching now and then...and often do it when I'm dropping down two or more gears at a time...6th to 4th or 3rd, 5th to 3rd or 2nd, 4th to 2nd, 3rd to 1st. It can be done while also using heal and toe techniques. As has been pointed out by a human typo finder..."heel" not "heal". Thank you sir.

The thing to remember about double de-clutching is that it doesn't need two full clutch movements and it doesn't need to be slow. Through the neutral phase the clutch only has to be lifted enough to spin up the input shaft which can be done with very little pedal movement if you know where your clutch bite point is.

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BBJ would say "heel", not "heal" when referring to Porsche driving.