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Double clutching is just releasing the clutch with the car in neutral then pushing it back in. This used to be needed more in the past. Note you dont have to rev match to call it double clutching, nor do you have to double clutch to rev match. But old cars used to not have syncro's, nor big trucks, and they had to rev match to save their gears(like an alpha spyder that auto crosses at Tech). But the reason trucks used to do this alot was clutch pressure. My grandfather used to drive them so i know alot about them, how i was taught was to drive like you have a load of water(means you gota be smooth). But you got this huge truck that has huge torque, which needs a big heavy pressure plate to keep it from slipping. Back then hydro clutches werent common place. So when they went to down shift going down a hill to slow down they also didnt have syncros so they had to rev match or grind their gears. So they had that huge pressure plate they had to move and hold, so it was hard as hell to hold the clutch in while you did all the rev matching and shifting so they put it in neutral and reved the engine up and then shifted in to gear. Saving their legs along with the clutch.
Now today we have syncros and light clutches. No real need to double clutch at all it actualy will make you slower. Then also you rarely need to rev match unless you are just really good and flying around a track, doing it wrong will slow you down. You can do without it if you dont know how to do it properly and go faster(heel toe that is). Cause you now dont have a big pressure plate so no need to keep your leg from getting tired, you hold it in while you heel-toe the gas and break while slowing down. Plus please dont go trying to learn how to do it on track that will just make people mad and possibly get you hurt.
oh yea there is no need to double clutch your tranny unless you drive a 20 ton 30 year old mack or something
All the "ricers" in my town think they are so cool! lol.
they must think it's the sh*t because Vin deisel said it in F&F.
and what's up w/ that first street race in the movie, like any of those other 3 cars could really hang w/ that TT RX-7.(how much did that thing sell for?)Give me that orange Supra and i'll probably smoke Vin diesel! haha
BTW, double clutching is for DOWN shifting and slowing for a turn on a race track. The only time I've ever seen it done was when my instructor at Summit Point did it in his S2000. Of course he races old British cars and was doing it just to stay consistent and to practice. Completely unnecessary in the S2000.
Double clutching is when you release the clutch to hit the gear 1,2nd,3rd...and then quick hit it again keeping your foot on the gas....when the revs get to say around 6500 let the clutch go.....chhiirrppppppp......the double clutch..
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89 S13 coupe stripped to a rollling chassis
Let's paint this bitch and get to the fun part!
As was alluded to, double clutching is a hold-over from non-synchro gearboxes. (and also non-dogring, non-synchro race boxes, usually with straight-cut gears) In these cases, double clutching was (is) necessary for downshifting.
If you run a synchro gearbox - 99.99% of the people on this list - there is no need to double-clutch (correct term is actually "double-de-clutch", but it's debatable) If you want to experience a reasonable facsimile, just drive w/o your clutch (hard on the synchros): (start off with higher gears - it's easier)
On downshift, move gear selector from 5th to N, blip throttle up to 3000 to 3500 or so - try 4th. 4th will engage when the revs are matched properly. It takes time to get the hang of it - don't force it, just try again.
I've been heel-and-toe down shifting with and w/o double clutching since I was 15 (I'm 31) and I still crunch gears from time-to-time. Lately, being interested in left foot braking for rallying, I've been braking with my left and clutchless downshifting - it works fine from 5 to 4 to 3, but I can't get 2nd - maybe because of the synchros or maybe the flywheel is too heavy for it.
Someone said it wasn't necessary to rev-match. I disagree. Being smooth is key to being fast - rev matching on corner entry is critical to being smooth.
A guy I co-drive for runs an Open class Ford Escort Cosworth RS with a Quaiffe Dog Box - that's the sh*t . As long as you rev match your downshifts, you never have to use the clutch (apart from taking off in 1st). With straight cut gears and dog ring engagement, it's what's needed for reliability on a turbo 4WD 300hp rally car. Plus the "chunk" sound it makes everytime you shift is very, very cool.
"Granny shifting, not double clutching like you should..."
"...now me and the mad scientist will have to rip apart the block to replace the piston rings you fried." ....yet he runs from the cops doing 100mph + right after that.
In the words of Dr. Evil: "RIOOOOOOGGHHHHHHTTTTTT"
Double clutching is when you release the clutch to hit the gear 1,2nd,3rd...and then quick hit it again keeping your foot on the gas....when the revs get to say around 6500 let the clutch go.....chhiirrppppppp......the double clutch..
hey guys, i actually tried the no clutch shift and it actuallly does work you just have to match the rev from the previous gear, but like the other guy said don't force it, be careful.
Oh, and there really is no point to doing it, unless your absolutely perfect at it, which would be very hard.
power shifting will work fine for me, i like chirping through gears!
Double-clutching is actually a critical step in pulling off proper rev-match heal-and-toe downshifts in a non-synchro car.
Here's why: What are you doing when you rev-match downshift? Well, you are doing two things. One, you are matching the speed of the engine to the speed of the wheels in the gear you are shifting into. This prevents the car from slowing after the shift, which transfers weight, overloads the tires, and leads to generally sloppy driving. This is really all you have to worry about with a good synchromesh transmission.
On a non-synchonized transmission, the rev match down shift is critical to get everything spinning at the same speed. This allows the gears to snick into place without grinding. OK, when you put your foot in on the clutch, the output shaft of the transmission is spinning at the same speed as the wheels (well, times the final drive ratio, but you get the point). With the clutch in, the engine spins at some other speed, and the transmission input shaft spins at a third speed (probably close to zero). Now, if you blip the throttle and do a rev match, you will ensure that the engine speed is appropriately matched to the transmission output shaft speed (assuming you are good at rev matching). However, since the clutch is in when you perform the throttle blip, the transmission input shaft speed is *NOT* tied to the engine speed. Therefore, it is not spinning at a speed that is matched to the transmission output shaft. With synchromesh, this doesn't matter. Just stuff the transmission in the next lower gear, and let the synchronizers figure everything out for you. With a non-synchronized transmission, this will grind gears.
This is why you use a double-cluth method. You push in the clutch, shift the car to neutral. Then you release the clutch. Now, the engine and the transmission input shaft are spinning at the same speed. Blip the throttle and match the engine speed to the vehicle speed at the lower gear. Since the clutch is out, the transmission input shaft speed will also be matched to the transmission output shaft speed. Now, quickly put your foot back in on the clutch. The inertia of the input shaft will keep it spinning close to it's previous, rev-matched speed, and the inertia of the flywheel will keep the engine speed approximately constant. Now, shift the transmission into the lower gear, and release the clutch.
You have just performed a heal-toe double-clutch downshift.
rallyrobin, beleive it or not, but heal-toe rev-match downshifting is not necessary for smooth driving. I have been told by Barry Brown (a National level Showroom Stock driver) that he does not use the traditional heal-toe rev match downshift. In fact, he does not rev match at all. He assured me that all top-level sedan racers (Neal Sapp, etc) use the same technique he does, and people he has instructed assured me that the technique does not upset the balance of the car in the slightest. It is supposedly a slightly faster way to execute the downshift. Barry explained the technique, but quite frankly I didn't understand it well enough to repeat it here. I still heal and toe :-)
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Rob Cadle
SE-R less
Nissan-less
Ride-less
Another-used-to-be-racer
It is supposedly a slightly faster way to execute the downshift.
I'm not sure exactly why a fast downshift is important. I mean, you're braking and slowing for a turn, why is it important to select a lower gear quickly? You don't need it until after you turn in.
I'm not sure exactly why a fast downshift is important. I mean, you're braking and slowing for a turn, why is it important to select a lower gear quickly? You don't need it until after you turn in.
To brake the car with the engine You read too much
To brake the car with the engine You read too much
Why would you want to do engine braking when you have things on each axle (calipers, pads and rotors) that are specifically designed to slow the car down?
. As long as you rev match your downshifts, you never have to use the clutch (apart from taking off in 1st). With straight cut gears and dog ring engagement, it's what's needed for reliability on a turbo 4WD 300hp rally car. Plus the "chunk" sound it makes everytime you shift is very, very cool.
