Korki Buchek

iTrader: (4)

Double Clutch = Clutch in -- disengage gear -- clutch out -- allow RPM to drop -- clutch in -- re-engage gear -- clutch out.

Rev Match = Clutch in -- disengage gear -- clutch out -- blip RPM to increase -- clutch in -- re-engage gear -- clutch out.

Spike100

^^

Or... just shift the car?

roast

iTrader: (2)

redlude97

iTrader: (11)

double clutching isn't necessarily just for upshifting, its just a method for revmatching before synchro's were used in trannies. Your "revmatch" is just a double clutch. The other method to revmatch with trannies with syncros is clutch in - blip rpm increase - downshift - clutch out. Does the same thing

Korki Buchek

iTrader: (4)

It's pretty easy, can be learned in a month's time, and saves your synchros from doing the work for you as well as saving your clutch from additional spins. Even with clutch planted on the floor, you're getting some wear on it by revving the engine. The same is not true if the clutch is all the way out and the car is in neutral.

NGZ

iTrader: (1)

You have the right idea, trying to rev-match. Get the revs right, and it should be smooth in any gear, up-shifting or down-shifting. Just make sure you're smooth because your revs match, and not because you're riding/feathering the clutch.

PhiSig

iTrader: (36)

I think it sounds like you are doing fine, the more you drive, the better you'll be.

Another common thing I see people do: When you are sitting at a light or standing still, you should always have the clutch pulled out and not in gear. Leaving it in gear with the clutch in puts premature wear on your throwout bearing.

redlude97

iTrader: (11)

But clutching in and out twice is putting more wear than a single depression. Double clutching is no longer needed, the synchros will not wear out prematurely with revmatching. Its also much faster to just blip revmatch than double clutch. No matter how fast you get, you can't pump the clutch twice and still be faster than my single pump.

Ziggyrama

iTrader: (15)

That is correct. Sitting at a light with the clutch pressed in is called "riding the clutch". It's not necessarily bad but it just wears out the bearings faster so the clutch lifespan will be decreased. Always drop into neutral at stop lights and let the clutch out. The idea is to use it only when actually shifting, not sitting on it.

To the OP, you're doing pretty well. Upshifting, downshifting, it's all the same. The basic idea is to match the speed of the engine to the speed of the transmission so that when you connect them back together, the difference between rotational speeds is minimal. It makes the synchros' life easier and will improve your shifting smoothness and speed. Here's the procedure I use that has worked on many cars I've owned in the past and does not stress your clutch and tranny:

1. Press the clutch in all the way
2. As you disconnect the engine from the tranny, the revs will start dropping at some rate.
3. Use the gas pedal to get the revs to a point where they will be once you engage the next gear. You have to know where that is and that comes with experience with the car.
4. Shift out of the gear you're in and move the stick into new gear with a slight pause at the gate of the new gear, just before it actually slips in. This is a very important step. The pause allows the machinery (synchros) to get the things synched so you don't mash things inside.
5. Hope you still got those revs close to where they should be
6. Slip into new gear.
6. Drive it like you stole it .

The pause in step 4 does not have to be long, fractions of a second. The key here is to allow the tranny to do its job. Just slamming gears will prematurely expire your transmission. It's all about feel here. When you're at the gate and things are ready, the stick should just slip in nice and easy. Pay attention to what the car likes when the tranny is hot or cold. For example, my 2nd gear synchro is a little stubborn when the tranny hasn't warmed up yet so my 1st -> 2nd shifts are little slower at first. Once things warm up, it's like butter. The skill of your rev match will be directly proportional to how long it will take for things to synch. If you can rev match well, the speeds will be close and you'll be able to shift very fast without issues and it will be smooth.

Work on this when you drive the car. Once you get it, it will become second nature. When you drive, note the Rev differences between gears. When I am in 3rd gear, I know that shift to 4th will drop me about 1000 RPMs. So, if I'm shifting at 4K RPMs from 3rd to 4th, I know I should rev match to about 3k RPMs. Getting accurate throttle modulation is key here. Takes practice but if done right, it's smooth and your passenger will notice how smooth you'll be.

As far as slipping the clutch, it's all about how long you really do it. Brief slip does not wear out the clutch sooner. The disks don't have a chance to warm up enough for bad things to start happening. When you're cooking the clutch, trust me, you'll know it. The smell will be hard to ignore. Just dropping the clutch is actually much worse because it shocks the transmission and differential. I always slip the clutch within reason, briefly, and it yields smooth transitions and I'v gotten some serious miles out of all clutches I ever owned. Again, it's all about feel here. If you think about it, clutch is much cheaper to replace than transmission. Keep dumping it and you will break it.

FALLEN1z

dont let anyone tell you that rev matching wears out your clutch with the whole better use for $600 thing. if you dont rev match you must slip the clutch when downshifting to keep from making the car jerk. rev matching allows you to do no slipping at all if you do it correctly and will SAVE your clutch. if you think about it it makes perfect sense

not rev matching= the need to slip the clutch to keep from the car jerking on downshifts

slipping clutch= increased wear

rev matching= little or no clutch slipping

rev matching=less wear

Mobil1Z

I havnt posted here in years but I just had to chime in and say that if you're doing this, you're an idiot.

Please, explain the benefit of shifting like this in any automobile built in the last 20 years.

Mobil1Z

"Rev-matching" is easily accomplished with a heel-toe downshift.

When understood, heel-toe is accomplished in less time than it takes to say "heel-toe downshift".

Korki Buchek

iTrader: (4)

Talk to me in a couple more years about your synchros and your clutch and why the car is making funny noises. Ask anyone who tracks their car whether they double clutch. And, if you're heal-toe downshifting w/o double clutch, you're doing something wrong.

spf4000

Then I guess every Japanese racer is doing something wrong.

http://www.youtube.com/watch?v=lKvF08Gt8N4

http://www.youtube.com/watch?v=wOZYdc8ftkY

They are all top GT drivers (both active and retired) in Japan, btw.

In a modern car, you don't need to double clutch on a downshift. I'm not saying you can't--in fact, for everyday driving, I do, just to be nicer to my synchros. But you're definitely wrong in saying that "And, if you're heal-toe downshifting w/o double clutch, you're doing something wrong."

Korki Buchek

iTrader: (4)

2:40; 3:46; etc.

spf4000

Look more carefully at the sequences you pointed out. They're downshifting two gears. That's why they are pushing in the clutch twice.

MrMojoRisin

I had a '83 Alfa Romero GTV 6 with shot syncromesh gears (notorious for that). I use to always have to double-clutch downshift or else they would grind, so that car conditioned me to always double clutch all my manual shift cars since then (totally uneccessary b/c of the syncromesh gears). Not one of those cars ever had the clutch wear prematurely and it is quite a nice feeling when you spin the gears and match the lower gear perfect and nail it! I also blip it on my motorcycles (obviously no double clutch)

Ps-Don't ever buy an Alfa Romero.

Korki Buchek

iTrader: (4)

So you mean to tell me that in the sequence where the guy hits the clutch twice within 1/2 a second he has just downshifted two gears. (3:46) What did he do, think he was going into one gear and then decide after he already got there -- in the split second between the shift -- that he was going to go into another? No, he is double clutching to accelerate out of a turn.

spf4000

My god, are you blind? He's only hitting the clutch once when he's UPSHIFTING. He's just doing it really fast. *Sigh* You're hopeless.

Korki Buchek

iTrader: (4)

I give up also. I don't really care. I double-clutch. A lot of people do; a lot of people don't.