Understanding Rev Matching
#1
Understanding Rev Matching
Being new to stick shifts, I'm trying to understand the sequence to rev matching. In going from 4th to 2nd, do I (1) fully depress the clutch, (2) press accelerator to raise RPMs to what they would be in 2nd, (3) release accelerator, (4) let out clutch? I'm assuming that I don't keep pressing the accelerator while releasing the clutch.
#3
Understanding Rev Matching
I've heard from different sources, including the guys on Car Talk, that pressing the accelerator while engaging the clutch causes excessive clutch wear. Although rev matching may reduce wear to other parts, seems like it's not helping prolong clutch life.
#4
Huh?
The whole point of rev matching is to get the engine to the speed of the transmission... to be more precise, the output shaft of the engine and the input shaft of the transmission.
You wear out the clutch if those two AREN'T going at similar enough rates for extended times.
If you press the clutch only partially (again, for any length of time), then you are going to wear the clutch out as it constantly slips.
The whole point of rev matching is to get the engine to the speed of the transmission... to be more precise, the output shaft of the engine and the input shaft of the transmission.
You wear out the clutch if those two AREN'T going at similar enough rates for extended times.
If you press the clutch only partially (again, for any length of time), then you are going to wear the clutch out as it constantly slips.
#5
Think of it as getting the speed of the engine where it would be when you have down shifted and released the clutch. If you didn't rev match, as soon as you would release the clutch the engine would race to a higher rpm because you're in a lower gear. Just get the engine speed to that higher rpm "before" you release the clutch.
#6
Romulus,
I think you were confusing rev matching to over-revving.
Double check your search, rev matching, when done correctly reduces wear on the clutch... and you can't rev match if you're letting off the gas when letting off the clutch.
I think you were confusing rev matching to over-revving.
Double check your search, rev matching, when done correctly reduces wear on the clutch... and you can't rev match if you're letting off the gas when letting off the clutch.
#7
[QUOTE=Romulus;912071]Being new to stick shifts, I'm trying to understand the sequence to rev matching. In going from 4th to 2nd, do I (1) fully depress the clutch, (2) press accelerator to raise RPMs to what they would be in 2nd, (3) release accelerator, (4) let out clutch? I'm assuming that I don't keep pressing the accelerator while releasing the clutch.[/QUOTE
There is a few types of driving. If you keep rpm below 3500 and shift vtec wont kick in and you should get the best mileage. If you rev the motor let say 5000 rpm you will get the most torque. If you drive near red line you will get the most horsepower. Torque is where you want to be if passing and 3500 or lower if you want the best mileage. As far a rpm matching it for manual in a semi where the rpm dont go higher than 2000 rpms and has dog gears so you match the rpms with shift with out the clutch. Dont try it, its a skill that take time to learn and has a different trans. If your talking about a ultra shift it an automated manual trans thats basically a manual trans with an automatic clutch, it has a clutch but no pedal.
There is a few types of driving. If you keep rpm below 3500 and shift vtec wont kick in and you should get the best mileage. If you rev the motor let say 5000 rpm you will get the most torque. If you drive near red line you will get the most horsepower. Torque is where you want to be if passing and 3500 or lower if you want the best mileage. As far a rpm matching it for manual in a semi where the rpm dont go higher than 2000 rpms and has dog gears so you match the rpms with shift with out the clutch. Dont try it, its a skill that take time to learn and has a different trans. If your talking about a ultra shift it an automated manual trans thats basically a manual trans with an automatic clutch, it has a clutch but no pedal.
#9
Being new to stick shifts, I'm trying to understand the sequence to rev matching. In going from 4th to 2nd, do I (1) fully depress the clutch, (2) press accelerator to raise RPMs to what they would be in 2nd, (3) release accelerator, (4) let out clutch? I'm assuming that I don't keep pressing the accelerator while releasing the clutch.
At each down shift you need to be sure you blip the throttle to the RPM's needed for the next down gear while shifting. A basic understanding of engine speed [RPM] to gear selection is needed. Thinking a bit about it, it isn't that hard to understand and it's essential to smooth shifting either up or down.
Unless you're driving flat out there's little need to have the accelerator to the floor. Just enough to match the RPM's to what's required at the next gear.
Stick shift driving is all about finesse. Gear selection and engine speed and ground speed all relate to each other. Learn to feel how it all fit's together.
Most always when you down shift you will need to raise the RPM to match the demand of a lower gear at your given speed. Well done it's as smooth as silk. Imperative at speed to maintaining control of the car. Under normal driving conditions it greatly reduces wear and tear on the mechanics making it all work. You will be driving like a pro.
And smiling as well_
Practice practice practice slowly.
K_C_
#10
Honda clutches are indestructable. My first car back in high school (the one on which I learned stick) was a 1992 Accord. I used it to teach my GF how to drive stick back in high school. I taught a good friend to drive stick on it. It endured all kinds of stupid abuse that gets heap onto a car by nature of being 16-21 and dumb.
Last I heard (which was about 5 years ago), it was STILL on the original clutch, and had just hit 170,000 miles.
Driving a stick is a fun skill... it's easy to learn how to do the basics, but takes time to become second nature. I don't know if you've ever wanted to ride a motorcycle, but knowing how to drive a standard transmission makes it far easier.
The most important thing to note, as Goobers mentioned above, is that leaving the clutch mostly engaged (say, with your foot lightly resting on it) is going to damage it. Cars use dry clutches, which aren't constantly bathed in oil and can't take that kind of abuse (like say, a motorcycle, where you tend to feather the clutch much more liberally). Push to disengage, release to engage, and keep your foot off otherwise, and it should be fine.
Last I heard (which was about 5 years ago), it was STILL on the original clutch, and had just hit 170,000 miles.
Driving a stick is a fun skill... it's easy to learn how to do the basics, but takes time to become second nature. I don't know if you've ever wanted to ride a motorcycle, but knowing how to drive a standard transmission makes it far easier.
The most important thing to note, as Goobers mentioned above, is that leaving the clutch mostly engaged (say, with your foot lightly resting on it) is going to damage it. Cars use dry clutches, which aren't constantly bathed in oil and can't take that kind of abuse (like say, a motorcycle, where you tend to feather the clutch much more liberally). Push to disengage, release to engage, and keep your foot off otherwise, and it should be fine.
#11
Amen Occam you, and Goober, hit it on the head. If you're going for the clutch you go for it, pussy footing around will destroy any clutch in a flash. Understanding what's happening is the key to success in all cases.
#12
Understanding Rev Matching
[quote=Goobers;912116]Huh?
I understand that you're not supposed to drive with the clutch partially depressed, but isn't this occuring (briefly) after you have reached the desired rpms and are releasing the clutch with the accelerator still down?
The All City Stick Driving School video teaches that clutches and accelerators are never to be engaged at the same time, e.g., when starting from a dead stop, you release the clutch until the car has rolled about half its length then fully release the clutch and only then apply gas. Also on an incline, you keep the foot brake pedal down, release clutch and only when you have movement fully release clutch and apply gas.
The Car Talk guys say that engaging the clutch while the accelerator is down will make you popular with clutch repairers everywhere.
I understand that you're not supposed to drive with the clutch partially depressed, but isn't this occuring (briefly) after you have reached the desired rpms and are releasing the clutch with the accelerator still down?
The All City Stick Driving School video teaches that clutches and accelerators are never to be engaged at the same time, e.g., when starting from a dead stop, you release the clutch until the car has rolled about half its length then fully release the clutch and only then apply gas. Also on an incline, you keep the foot brake pedal down, release clutch and only when you have movement fully release clutch and apply gas.
The Car Talk guys say that engaging the clutch while the accelerator is down will make you popular with clutch repairers everywhere.
#13
Romulus That driving school is telling you how to start off from a dead stop. I don't believe they say hold the clutch until, but more like release it at a rate that will get the car going and you should be off the clutch before the car moves 1/2 its length. Good advice for a beginner. From a dead stop you set the accelerator them release the clutch in one smooth operation, without popping it, as you continue to depress the accelerator, getting it up to speed for the next shift.
It takes practice to get it right. The learning curve should really not harm things. As you understand, the clutch is either down to the floor with your foot on it or sitting pretty with your left foot on the floor - it really isn't a variable position item. It's engaged or not.
Your concern regarding the clutch and position of the accelerator are valid, however, you need to have the engine revving at the proper speed to match the transmission gearing. What you're talking about is the moment the clutch engages. You will only be blip-ping the gas pedal, not slamming it to the floor. By a positive quick release of the clutch the wear is minimal and is exactly what the clutch is designed for. Positive engagement - no slipping.
You'll get it down.
K_C_
It takes practice to get it right. The learning curve should really not harm things. As you understand, the clutch is either down to the floor with your foot on it or sitting pretty with your left foot on the floor - it really isn't a variable position item. It's engaged or not.
Your concern regarding the clutch and position of the accelerator are valid, however, you need to have the engine revving at the proper speed to match the transmission gearing. What you're talking about is the moment the clutch engages. You will only be blip-ping the gas pedal, not slamming it to the floor. By a positive quick release of the clutch the wear is minimal and is exactly what the clutch is designed for. Positive engagement - no slipping.
You'll get it down.
K_C_
#14
depending on speed and which gear, i dont lift the throttle and just cluth-in, engage lower gear at the right rpm. especially when im in a higher gear where im kinda bogging to get more power out, i just do that. much faster than letting off throttle, clutch-in, blip, and engage.
#15
Being new to stick shifts, I'm trying to understand the sequence to rev matching. In going from 4th to 2nd, do I (1) fully depress the clutch, (2) press accelerator to raise RPMs to what they would be in 2nd, (3) release accelerator, (4) let out clutch? I'm assuming that I don't keep pressing the accelerator while releasing the clutch.
1. Release gas, press clutch
2. Begin moving shifter from 4th to 3rd
3. Tap the gas while the shifter is moving (usually when it crosses neutral) to where the rpms would be
4. Release clutch when shifter is in 3rd
5. Press gas (if you intend to accelerate)
This is basically what you do, though obviously it's not as simple as it sounds when you're learning it. Kind of like learning how to operate a clutch when you first start driving stick, you'll just have to perfect your timing. You'll know when it's done correctly, and it becomes more fluid after a while. I think I taught myself how to do it within a week or two in my older brother's Civic when I was in college.
The people you were talking about are technically correct about pressing the accelerator increasing clutch wear, but that's not the end of the story. For example, people who give the car too much gas and too early when they shift will cause excessive and unnecessary wear. But while you are depressing the gas pedal with the clutch in while rev-matching, it is minimizing the wear, compared to people who just downshift and release the clutch without rev-matching. That kind of behavior makes your clutch work harder to match the speeds of the engine and the transmission, whereas rev-matching will make the clutch not have to cope with that duty, especially when you're dealing with modern cars with synchros. But back when cars didn't have them, you'd have to double-clutch (which I used to do), which was basically the same thing except you release the clutch in neutral, blip the throttle, then put the clutch in and shift into the desired gear. It's unnecessary at this point, but there's nothing bad about doing it.
#16
great thread guys. Really learning a lot.
one more question though. I understand rev matching if I need to accelerate. Ie: downshifting to accelerate on a onramp.
But, what about downshifting at a light/ stop sign or if someone is turning left ahead and you want to change lanes. I know that some people say this isn't necessary. BUT for the sake of this discussion, let's just say I need to. (for changing lanes). So I need to brake but would also like to prep for a lane change if possible. If I rev match, then I take my foot off the brake to tap the gas while downshifting right?.
Isn't that dangerous? I'm planning to stop, but with the clutch pressed, (it's going to roll freely in neutral), and now my foot is not on the brake anymore....
What do you guys do in that situation? I hope it makes sense. It's just something i've been trying to learn and it would be awesome to see what others do.
one more question though. I understand rev matching if I need to accelerate. Ie: downshifting to accelerate on a onramp.
But, what about downshifting at a light/ stop sign or if someone is turning left ahead and you want to change lanes. I know that some people say this isn't necessary. BUT for the sake of this discussion, let's just say I need to. (for changing lanes). So I need to brake but would also like to prep for a lane change if possible. If I rev match, then I take my foot off the brake to tap the gas while downshifting right?.
Isn't that dangerous? I'm planning to stop, but with the clutch pressed, (it's going to roll freely in neutral), and now my foot is not on the brake anymore....
What do you guys do in that situation? I hope it makes sense. It's just something i've been trying to learn and it would be awesome to see what others do.
#17
heel and toe, but on this car i use the side of my foot to blip.
so you brake with your right foot and use the side of your right foot to blip the throttle to rev match.
imho, unless one can master this you're really not 'driving' MT.
so you brake with your right foot and use the side of your right foot to blip the throttle to rev match.
imho, unless one can master this you're really not 'driving' MT.
#18
one more question though. I understand rev matching if I need to accelerate. Ie: downshifting to accelerate on a onramp.
But, what about downshifting at a light/ stop sign or if someone is turning left ahead and you want to change lanes. I know that some people say this isn't necessary. BUT for the sake of this discussion, let's just say I need to. (for changing lanes). So I need to brake but would also like to prep for a lane change if possible. If I rev match, then I take my foot off the brake to tap the gas while downshifting right?.
Isn't that dangerous? I'm planning to stop, but with the clutch pressed, (it's going to roll freely in neutral), and now my foot is not on the brake anymore....
What do you guys do in that situation? I hope it makes sense. It's just something i've been trying to learn and it would be awesome to see what others do.
But, what about downshifting at a light/ stop sign or if someone is turning left ahead and you want to change lanes. I know that some people say this isn't necessary. BUT for the sake of this discussion, let's just say I need to. (for changing lanes). So I need to brake but would also like to prep for a lane change if possible. If I rev match, then I take my foot off the brake to tap the gas while downshifting right?.
Isn't that dangerous? I'm planning to stop, but with the clutch pressed, (it's going to roll freely in neutral), and now my foot is not on the brake anymore....
What do you guys do in that situation? I hope it makes sense. It's just something i've been trying to learn and it would be awesome to see what others do.
#20