Quick question about "rev-matching" and wearing on the clutch.
#21
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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.
Rev Match = Clutch in -- disengage gear -- clutch out -- blip RPM to increase -- clutch in -- re-engage gear -- clutch out.
#23
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Originally Posted by Korki Buchek
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.
Rev Match = Clutch in -- disengage gear -- clutch out -- blip RPM to increase -- clutch in -- re-engage gear -- clutch out.
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Originally Posted by Korki Buchek
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.
Rev Match = Clutch in -- disengage gear -- clutch out -- blip RPM to increase -- clutch in -- re-engage gear -- clutch out.
#25
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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.
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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.
#27
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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.
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.
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Originally Posted by Korki Buchek
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.
#29
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Originally Posted by PhiSig
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.
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.
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.
Last edited by Ziggyrama; 06-15-2007 at 12:56 PM.
#30
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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
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
#31
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Originally Posted by Korki Buchek
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.
Rev Match = Clutch in -- disengage gear -- clutch out -- blip RPM to increase -- clutch in -- re-engage gear -- clutch out.
Please, explain the benefit of shifting like this in any automobile built in the last 20 years.
#33
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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.
#34
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Originally Posted by Korki Buchek
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.
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."
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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.
Ps-Don't ever buy an Alfa Romero.
#38
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Originally Posted by 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.
#39
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Originally Posted by Korki Buchek
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.