Some rev-matching questions
Joined: Jan 2008
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Originally Posted by Mark355,Oct 10 2009, 02:32 PM
Some people just clutch-in and don't downshift when approaching a redlight or stop sign, but I love downshifting my car. I always try to rev-match (and never skip gears) so the synchros don't have to strain to raise the engine speed by themselves, but I don't always get it right. What I'm noticing is that if I don't blip hard enough, I can feel the car jerk/buck a little bit when the clutch it let out and the synchros kick in to do their job. Even if I'm short by a small amount such as 200 - 300 rpm, I can feel a little jerk and I know the car is telling me that I was close but no cigar. Nothing violent, but you feel it.
However, if I overshoot the mark even by as much as 1k rpm, I don't feel a buck. The revs just drop very quickly to the correct rpm for the lower gear when I let the clutch out and it feels ok. Am I correct in assuming there's more strain on my synchros and drivetrain when I don't blip the throttle enough as opposed when I do it a little too much? Can anyone explain why? Is it because once the revs reach the peak for that blip, they begin coming down and since the wheels are also slowing, it's easier for synchros to "pull" the rpm down to the correct point once the clutch is engaged? The car certainly seems to react worse when the revs are still too low for the gear I downshift to.
When I downshift, I clutch-in, blip as I'm moving the lever, and let the clutch out at the same speed that I let it out on an average upshift. Should I be engaging the clutch a little slower on a downchange or is this ok? While doing this, I hardly look at my tach--I do it all by ear and just kinda estimate how much to blip and when exactly to let out the clutch. I don't see how you can be exact all the time? You can definitely get close once you're familiar with the car and ratios, but even the best drivers miss the mark sometimes right?
At this point, I almost always downshift into 5th, 4th, and 3rd. I can do all of these pretty smoothly I'd say 9/10 times. 2nd is harder because there's a bigger difference in ratios but I'm practicing. I never downshift into 1st when already moving.
Just want to make sure I'm doing this properly and am being as kind to my drivetrain as I can before I start practicing heel-toe. Any insight appreciated!
However, if I overshoot the mark even by as much as 1k rpm, I don't feel a buck. The revs just drop very quickly to the correct rpm for the lower gear when I let the clutch out and it feels ok. Am I correct in assuming there's more strain on my synchros and drivetrain when I don't blip the throttle enough as opposed when I do it a little too much? Can anyone explain why? Is it because once the revs reach the peak for that blip, they begin coming down and since the wheels are also slowing, it's easier for synchros to "pull" the rpm down to the correct point once the clutch is engaged? The car certainly seems to react worse when the revs are still too low for the gear I downshift to.
When I downshift, I clutch-in, blip as I'm moving the lever, and let the clutch out at the same speed that I let it out on an average upshift. Should I be engaging the clutch a little slower on a downchange or is this ok? While doing this, I hardly look at my tach--I do it all by ear and just kinda estimate how much to blip and when exactly to let out the clutch. I don't see how you can be exact all the time? You can definitely get close once you're familiar with the car and ratios, but even the best drivers miss the mark sometimes right?
At this point, I almost always downshift into 5th, 4th, and 3rd. I can do all of these pretty smoothly I'd say 9/10 times. 2nd is harder because there's a bigger difference in ratios but I'm practicing. I never downshift into 1st when already moving.
Just want to make sure I'm doing this properly and am being as kind to my drivetrain as I can before I start practicing heel-toe. Any insight appreciated!
i have done a UOA on the gearbox lubes and 70,000 kms worth of such technique hasnt resulted in any abnormal wear. Top notch condition according to the technician.
i would use it all the time. especially in the wet. the lesser the mismatch (best if none) the less jerk u take away from the transition which can steal that tiny last fraction of grip u need.
Thread Starter
Joined: Jul 2008
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From: Troy, NY
Thanks everyone for your input. So basically in terms of synchro wear, it doesn't really matter whether I blip too little or too much when single clutching because I'm only working to match the speed of the engine to the wheels and not the input shaft. The synchros need to work to increase the shaft speed regardless of whether I rev-match perfectly. Honestly I don't see myself double clutching because there's no way around that it's more steps and slower. I can downshift smoothly and almost seamlessly the majority of the time without double-clutching. My gears never grind or fight me. Guess I'll just have to accept that my synchros are going to do some work, albeit what they were designed to do. As I said before, I don't skip gears and I know that's the real synchro killer. I've read archived threads on it from Woodwork.
BTW when slowing down, I never put the car in neutral and just coast/brake to a stop. I always like to be in gear when moving in case I need to speed up to avoid the path of something in an emergency situation. I'll brake a little, downshift rev-match, and brake some more while in gear. I try not to use the engine compression to slow down the car solely. Plus downshifting sounds awesome and it's a great feeling when you rev-match three gears in a row perfectly approaching a slow corner.
Now how about wear and stress on the clutch? In keeping with my single-clutch technique, if I try to rev-match but don't blip hard enough, how bad is that for the clutch when I let the pedal out? How about when I blip and rev it a little too high? Just trying to assess the wear on my drivetrain because I get my blips wrong on occasion. I'm not perfect.
BTW when slowing down, I never put the car in neutral and just coast/brake to a stop. I always like to be in gear when moving in case I need to speed up to avoid the path of something in an emergency situation. I'll brake a little, downshift rev-match, and brake some more while in gear. I try not to use the engine compression to slow down the car solely. Plus downshifting sounds awesome and it's a great feeling when you rev-match three gears in a row perfectly approaching a slow corner.
Now how about wear and stress on the clutch? In keeping with my single-clutch technique, if I try to rev-match but don't blip hard enough, how bad is that for the clutch when I let the pedal out? How about when I blip and rev it a little too high? Just trying to assess the wear on my drivetrain because I get my blips wrong on occasion. I'm not perfect.
Joined: Sep 2008
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rev-matching does nothing for syncro wear, may help on other parts of the drive train, but not the syncros. If you are really concerned with wear you would just pop it into neutral coming to stop lights and forget about downshifting, if you wanted to downshift you would double clutch rev-match.
Rev-match downshifting is good for keeping the car balanced when downshifting, if we did not have syncros we would have to double clutch when doing this.
I rev-match at stoplights sometimes just to practice rev-matching, it is actually more difficult to do this at slower street speeds.
I understand you wanting to stay in gear "just in case", but you do realize that a good amount of accidents are caused by someone making an evasive manuver to get out of the way from some stupid driver. The problem with this is given the situation (you are approaching a stop light) you are mostly worried about getting rear ended. So say you do see someone comming up fast and you manage to get to the other lane, because of your quick reactions and being that you are in gear you make it. BUT you failed to notice the "other car" and bam!!, lets just hope we are on a 4 lane and the "other car" is moving the same direction as you are, but either way you are now at fault. I am not saying it is a bad thing about being aware and ready for anything, but IMO issues that happen at redlights that you see and are stopping for are most of the time not your fault, not going to be that bad, and better left that way.
Rev-match downshifting is good for keeping the car balanced when downshifting, if we did not have syncros we would have to double clutch when doing this.
I rev-match at stoplights sometimes just to practice rev-matching, it is actually more difficult to do this at slower street speeds.
I understand you wanting to stay in gear "just in case", but you do realize that a good amount of accidents are caused by someone making an evasive manuver to get out of the way from some stupid driver. The problem with this is given the situation (you are approaching a stop light) you are mostly worried about getting rear ended. So say you do see someone comming up fast and you manage to get to the other lane, because of your quick reactions and being that you are in gear you make it. BUT you failed to notice the "other car" and bam!!, lets just hope we are on a 4 lane and the "other car" is moving the same direction as you are, but either way you are now at fault. I am not saying it is a bad thing about being aware and ready for anything, but IMO issues that happen at redlights that you see and are stopping for are most of the time not your fault, not going to be that bad, and better left that way.
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Originally Posted by Mark355,Oct 10 2009, 06:06 PM
Thanks everyone for your input. So basically in terms of synchro wear, it doesn't really matter whether I blip too little or too much when single clutching because I'm only working to match the speed of the engine to the wheels and not the input shaft. The synchros need to work to increase the shaft speed regardless of whether I rev-match perfectly. Honestly I don't see myself double clutching because there's no way around that it's more steps and slower. I can downshift smoothly and almost seamlessly the majority of the time without double-clutching. My gears never grind or fight me. Guess I'll just have to accept that my synchros are going to do some work, albeit what they were designed to do. As I said before, I don't skip gears and I know that's the real synchro killer. I've read archived threads on it from Woodwork.
BTW when slowing down, I never put the car in neutral and just coast/brake to a stop. I always like to be in gear when moving in case I need to speed up to avoid the path of something in an emergency situation. I'll brake a little, downshift rev-match, and brake some more while in gear. I try not to use the engine compression to slow down the car solely. Plus downshifting sounds awesome and it's a great feeling when you rev-match three gears in a row perfectly approaching a slow corner.
Now how about wear and stress on the clutch? In keeping with my single-clutch technique, if I try to rev-match but don't blip hard enough, how bad is that for the clutch when I let the pedal out? How about when I blip and rev it a little too high? Just trying to assess the wear on my drivetrain because I get my blips wrong on occasion. I'm not perfect.
BTW when slowing down, I never put the car in neutral and just coast/brake to a stop. I always like to be in gear when moving in case I need to speed up to avoid the path of something in an emergency situation. I'll brake a little, downshift rev-match, and brake some more while in gear. I try not to use the engine compression to slow down the car solely. Plus downshifting sounds awesome and it's a great feeling when you rev-match three gears in a row perfectly approaching a slow corner.
Now how about wear and stress on the clutch? In keeping with my single-clutch technique, if I try to rev-match but don't blip hard enough, how bad is that for the clutch when I let the pedal out? How about when I blip and rev it a little too high? Just trying to assess the wear on my drivetrain because I get my blips wrong on occasion. I'm not perfect.
I read through thsoe threads as well, so half of my information comes from them.Id assume the clutch wear is not what you should be concerned about. A small jerk just means the clutch si grabbing. You'd do much more damage to the clutch by slipping it excessively on startup. I doubt much people who drive the s2000 can drive it perfectly without jerking it unless they slip the clutch like crazy on shift ups or they're pro.
I'm more concerned about the effects of it further down the line, like the rear end since thats the weakest point of our cars..
Joined: Sep 2008
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Another thing that should be noted is that rev-matching either way is much nicer on the engine when downshifting. Infact I honestly think that with the retainers as junk as they are on the AP1s, that real hard downshifts could to as much/more harm than miss-shifts.
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Joined: Jun 2006
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From: Littleton, CO
Originally Posted by Mark355,Oct 10 2009, 08:06 PM
So basically in terms of synchro wear, it doesn't really matter whether I blip too little or too much when single clutching because I'm only working to match the speed of the engine to the wheels and not the input shaft. The synchros need to work to increase the shaft speed regardless of whether I rev-match perfectly.....Guess I'll just have to accept that my synchros are going to do some work, albeit what they were designed to do. As I said before, I don't skip gears and I know that's the real synchro killer. I've read archived threads on it from Woodwork.
Now how about wear and stress on the clutch? In keeping with my single-clutch technique, if I try to rev-match but don't blip hard enough, how bad is that for the clutch when I let the pedal out? How about when I blip and rev it a little too high? Just trying to assess the wear on my drivetrain because I get my blips wrong on occasion. I'm not perfect.
http://www.metacafe.com/watch/yt-_HjXXUyQh...l_walther_rohl/
Good job on your research, enjoy the car.
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Joined: Oct 2007
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From: Mooresville, NC
Definitely no need to double clutch with this car at all.
If you are off by a little bit it will still be less than if you were just downshifting without rev matching at all so will still be better off than a normal downshift.
If you are off by a little bit it will still be less than if you were just downshifting without rev matching at all so will still be better off than a normal downshift.
