merovi

iTrader: (7)

What is double clutching? what advantage does it have?

2k2kev

Absolutely none in a car made since about 1960.

Watch F&F last night, didja?

Progress

iTrader: (26)

You are essentially rev matching the engine to the gear while you are in neutral. I do it when I downshift so the shifter slides in well. It was requisite in cars/trucks that did not have synchros. Nowadays, like kev said, you don't need to do it.

2k2kev

I definitely blip the throttle when downshifting to match the revs, but actual double-clutching isn't necessary. It won't hurt anything, though, so have fun if you want.

UGAd13

Double-clutching is a gear shifting procedure to save wear and tear on your gearbox, and on your clutch, at the expense of a little extra work for your left leg.

Let's say you're accelerating in second gear. When you're ready to shift into third, you decide not to use the standard approach, which is just to tromp on the clutch, take your foot off the gas, shove the shift lever into third, and let the clutch back out. Instead, you opt to double-clutch properly:

First, you take your foot off the gas and kick in the clutch. You shift into neutral, AND let the clutch out. You wait perhaps 0.3 to 1.0 seconds for the engine to slow down from its high revs, depending on how fast you were revving when you started to shift and how much inertia the engine has to slow down. THEN you kick in the clutch and shift into third, and let the clutch out quickly, feeding the gas appropriately. If you have judged it right, when you let the clutch out, there isn't any JERK. And when you shove the lever into third, the gears and engine are at a synchronized speed, so there's minimum wear on the synchronizers, which are the tiny clutches that bring the clutch plate and the gears into smooth synchrony. There's also usually less wear on the clutch plates.

What's the big deal? The main point is that when you try to shift into third gear, the engine has slowed itself and the clutch plate down to the right speed—just about the same speed as the gearbox—so it saves wear on the synchronizers and the clutch. It can also save shock and strain on the whole drive-train, because the speeds are just about synchronized when you let out the clutch.

Double-clutching can aslo be used when down-shifting. You have to shift into neutral and then blip the throttle momentarily before you shift into the lower gear. It requires practice and a good feel, a good touch, to do it right, especially considering the embarrassing noises you make if you miss your shift into a low gear on a crash-box. For example, you should aim to have the revs just a little high, so if you miss, the engine will soon slow down, and then gears will be at the right speed to mesh and the cogs will slip in....

Smooth transitions are everthing in racing. If you're downshifting during a turn at a road course and you're cornering at the limit, a sudden lurch in your car isn't going to be too pretty. Say hello to the curb/barrier or whatever is going to catch you when you spin out. Double clutch properly, and you'll be faster/smoother at the track.

Most modern streetcars don't need double-clutching, because they have a synchromesh transmission, in which the synchronizers decide which pair of gears to connect to their shaft.

-I just googled that, you can't escape the google.

MrRogerStatus

iTrader: (4)

OMG- there is people that down-shift after all.

J/K

Fezzik

iTrader: (2)

A lot of semi trucks actually have to double clutch.

Galo

Correct -you dont need to DC- but I have been double-clutching in all my manual gearboxes since I first learned to drive stick in my bro's 1963 MGB with its non-synchro first gear and I can guarantee you that my constant and consistent double-clutching (when downshifting only) is one of the reasons why all my cars -even with trannys with >150k miles- still had perfect synchros when I sold the car.....

2k2kev

You opened them up and verified that? Because I've never double-clutched and I have yet to replace one.

Four cars driven at least 80k miles each, all on original clutch when I sold them. I still know the owner of one and it's still going fine at 120k.

Galo

Nope. My definition of fine is simple: when shifted fast, it was as smooth as it was when it was new.....

2k2kev

Never double-clutched in my life, exact same result.

Ben

Double de-clutching is very useful for performance driving.
I double de-clutch when autocrossing. I do it the rest of the time to practice.

That combined with heal-and-toe driving can signifcantly smooth your downshifts. Smooth is fast.

kratz74

Its not that simple. Press clutch when shifting out of gear and again when gong into the next gear...like others described. However, I have actually raced (not the Maixma) and double clutching is not needed or beneficial in modern vehicles-wastes time. You can rev match easily without double clutching. Maybe some rally car racers are here-they'd probably be the ones who could confirm. Someone autocrossing in a parking lot between orange cones is not a racer. Going nearly well over 150 mph into a corner needing to downshift and perfectly revmatch or you will crash - taught me theres no benefit to double clutching or you will get passed.

Progress

iTrader: (26)

One thing I notice when I down shift from say 4th to 2nd and I'd be going at a rate where the car would be about 4k RPM and the tach is only at 2k RPM, the stick will have to be shoved pretty hard to get into 2nd. So I pull out of 4th and before I put the stick into 2nd I match revs then put it in gear and immediately pull off the clutch pedal. It isn't very fast but during daily driving I like to do it.

MorpheusZero

iTrader: (10)

Double clutching is unnecessary. Every dumbass out there who lives by the F&F book will think that powershifting is called double clutching. But it's not.

Heel-toeing is great for twisty roads, especially when you're RWD. It helped me smoke a 5th gen max in a twisty road with a stock '92 miata. Given, it wasn't a high speed road and I also managed to smoke a 330Ci w/sports package. But that's just me bragging/wanting to tell stories.

Bottom line, heel-and-toeing is great. And you don't need to double-clutch nowadays, but I always rev-match when I downshift, it makes for a much funner drive, and it sounds l337. Hehe.

Hmm, lots of hyphens.

2k2kev

You registered to make that post? I'm in awe... in one post you correctly used a bunch of hyphens, made fun of anyone who thinks F&F has even a speck of reality, correctly identified and used automotive terms, and didn't mention "intake."

We need more noobs like you

lex3015

i do it sometime when im downshifting, but yeah like they all said more or less its pointless.....

MorpheusZero

iTrader: (10)

*cough* oh, right.