Is it me or the...
Registered User
Joined: Nov 2003
Posts: 196
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From: san diego
i think what everyone is trying to say is...
it's you. (j/k)
i've driven a stick for 20 years and have never needed to "downshift" into 1st gear. it's cheaper to just use your brakes. they are much cheaper to replace than a clutch or a transmission synchro.
it's you. (j/k)
i've driven a stick for 20 years and have never needed to "downshift" into 1st gear. it's cheaper to just use your brakes. they are much cheaper to replace than a clutch or a transmission synchro.
Joined: Mar 2001
Posts: 37,305
Likes: 18
Guys, I think he's talking about his shift "to" 2nd and why it's jerky unless he prevents the clutch from going the last 10% of its travel on the way up.
If you are needing to do this, that just means your clutch/throttle/shift coordination is off PLUS, you are not matching the revs closely enough at the precise moment of clutch release. By doing what you do to make the shift smoother, you are slipping the clutch a bit to absorb the mis-matched revs that is the result of your slightly incorrect timing of all your controls. If you keep doing this, your clutch will wear out that much sooner.
I think we all know (and should use) rev matching on a "downshift", however, matching revs on an "upshift" will also make for a more "professional" shift. "Upshift" rev matching is simply allowing the engine revs to come down to the approximate speed needed to smoothly engage the next higher gear. Only practice will get this right. You time the clutch action, shift action to coincide with exactly when the rpm has fallen to the correct speed so that when you let the clutch out fully, the tranny input shaft and the output shaft are spinning at about the same speed. Then, when you apply the throttle, you will continue to speed up without jerking. Too high rpm, you will lurch forward. Too low rpm, you will be pulled back. Further throttle modulation at this time will result in a jerky motion.
If you are needing to do this, that just means your clutch/throttle/shift coordination is off PLUS, you are not matching the revs closely enough at the precise moment of clutch release. By doing what you do to make the shift smoother, you are slipping the clutch a bit to absorb the mis-matched revs that is the result of your slightly incorrect timing of all your controls. If you keep doing this, your clutch will wear out that much sooner.
I think we all know (and should use) rev matching on a "downshift", however, matching revs on an "upshift" will also make for a more "professional" shift. "Upshift" rev matching is simply allowing the engine revs to come down to the approximate speed needed to smoothly engage the next higher gear. Only practice will get this right. You time the clutch action, shift action to coincide with exactly when the rpm has fallen to the correct speed so that when you let the clutch out fully, the tranny input shaft and the output shaft are spinning at about the same speed. Then, when you apply the throttle, you will continue to speed up without jerking. Too high rpm, you will lurch forward. Too low rpm, you will be pulled back. Further throttle modulation at this time will result in a jerky motion.
Registered User
Joined: Apr 2003
Posts: 8,595
Likes: 54
From: Temple City
xviper, if its not too much trouble, do you think you can post an estimate of what the rpm should be at before engaging into the next gear if we shift at redline?
For example, I hit redline in 1st gear, then I press the clutch all the way, put the shifter into second, wait for the rpm to drop all the way down to what rpm? And then I let go of the clutch fully?
I usually redline, clutch pedal in, shifter into 2nd, and let the clutch out slowly while applying a little throttle...and then full throttle again.
For example, I hit redline in 1st gear, then I press the clutch all the way, put the shifter into second, wait for the rpm to drop all the way down to what rpm? And then I let go of the clutch fully?
I usually redline, clutch pedal in, shifter into 2nd, and let the clutch out slowly while applying a little throttle...and then full throttle again.
Registered User
Joined: Jan 2003
Posts: 8,482
Likes: 3
From: Wylie, TX
[QUOTE]Originally posted by jyeung528
xviper, if its not too much trouble, do you think you can post an estimate of what the rpm should be at before engaging into the next gear if we shift at redline?
For example, I hit redline in 1st gear, then I press the clutch all the way, put the shifter into second, wait for the rpm to drop all the way down to what rpm?
xviper, if its not too much trouble, do you think you can post an estimate of what the rpm should be at before engaging into the next gear if we shift at redline?
For example, I hit redline in 1st gear, then I press the clutch all the way, put the shifter into second, wait for the rpm to drop all the way down to what rpm?
Joined: Mar 2001
Posts: 37,305
Likes: 18
jyeung528, your question is a very difficult one to answer, however, mxt_77's reply is a good place to begin. Rev matching on an upshift can be just as tricky as doing it on a down shift. One thing usually remains constant if you do it correctly and that is the rate at which the engine speeds fall once the gas is released during a shift. What needs to happen is for the driver to time the rest of the shifting steps so that the whole thing is completed and the clutch let out at the best possible engine speed as you continue on your way.
The scenario you speak of where you go to redline suggests that your are trying to accelerate in brisk fashion and that there is some urgency in what you are trying to do. Letting the clutch out slowly and applying a "little" throttle in this example will NOT work well for you. This will become "JERK CITY" because your revs will have dropped waaaaay below what it needs to be by the time you get under way again. Shifting with "urgency" (ie. at redline) should be done almost as fast as humanly possible. The whole shift should be completed in a fraction of a second. If you are too slow at it, you may as well wait a real long time till your car slows down enough for the drive wheel speeds to come "down" to meet your engine speed. You should practice till you can basically do the whole shift in the time that it takes you to push the clutch to the floor and let it go. Obviously, you do not do this if you are just driving normally around town.
I had a vid taken inside the car with me doing a series of full throttle upshifts but that server is gone and it's no longer availabe. If your email server will allow a 4MB attachment, PM me your email address and I'll send it to you.
The scenario you speak of where you go to redline suggests that your are trying to accelerate in brisk fashion and that there is some urgency in what you are trying to do. Letting the clutch out slowly and applying a "little" throttle in this example will NOT work well for you. This will become "JERK CITY" because your revs will have dropped waaaaay below what it needs to be by the time you get under way again. Shifting with "urgency" (ie. at redline) should be done almost as fast as humanly possible. The whole shift should be completed in a fraction of a second. If you are too slow at it, you may as well wait a real long time till your car slows down enough for the drive wheel speeds to come "down" to meet your engine speed. You should practice till you can basically do the whole shift in the time that it takes you to push the clutch to the floor and let it go. Obviously, you do not do this if you are just driving normally around town.
I had a vid taken inside the car with me doing a series of full throttle upshifts but that server is gone and it's no longer availabe. If your email server will allow a 4MB attachment, PM me your email address and I'll send it to you.
