Correct way to rev match in a 6MT when downshifting?
07-06-2010, 01:40 PM
#1
Advanced
Thread Starter
Correct way to rev match in a 6MT when downshifting?
Been reading on a few forums and it seems there are lots of different opinions on what is the 'correct' way to rev match when downshifting gears. Here are the two main techniques that I've gathered when downshifting from ie. 4th to 3rd gear:
A: While in 4th gear, clutch in (disengage clutch), shift to 3rd gear, blip the throttle to anticipated RPM, clutch out (engage clutch)
B: While in 4th gear, clutch in, shift to Neutral, clutch out, blip throttle to anticipated RPM, clutch in, shift to 3rd gear, clutch out
As I understand, technique A is rev match downshifting while technique B is the same thing with the addition of double clutching. As well, people say that B is the most proper way to rev match downshift because it engages certain parts of the transmission (ie. syncros) that A does not.
For a 3rd gen 6MT, what would be you consider to be the most appropriate way to rev match down shift and why?
A: While in 4th gear, clutch in (disengage clutch), shift to 3rd gear, blip the throttle to anticipated RPM, clutch out (engage clutch)
B: While in 4th gear, clutch in, shift to Neutral, clutch out, blip throttle to anticipated RPM, clutch in, shift to 3rd gear, clutch out
As I understand, technique A is rev match downshifting while technique B is the same thing with the addition of double clutching. As well, people say that B is the most proper way to rev match downshift because it engages certain parts of the transmission (ie. syncros) that A does not.
For a 3rd gen 6MT, what would be you consider to be the most appropriate way to rev match down shift and why?
07-06-2010, 01:44 PM
#2
Here are some excerpts from some writings I've done over the years. Hope these get you started in the right direction. If you have questions, please feel free to ask.
And remember. Just because someone has been driving a manual transmission for years does not mean they know how to do it correctly. Don't absorb bad habits.
================================================== ========
What follows is a collection of writings which I have posted at various times on this website in an effort to help answer some questions regarding the proper manner in which a manual transmission should be operated. While there are certainly many ways to drive a car with a manual transmission, there is really only one correct way. I was most fortunate to have learned these techniques while I was still in my teenage years. In so doing, I was able to avoid developing entrenched habits before they became really bad habits and difficult to correct. It is my hope that this helps you learn what I have learned and perfected over the years. If you do, you will reap the rewards, both financial and in the knowledge that you have mastered a technique that few do in their lifetimes. Have fun!
Under normal driving situations (not racing), when you start out from a standing start, you do so with the lowest possible RPMs, get the clutch out to full engagement as soon as you can while adding throttle. If you do this correctly, the transition will be smooth and seamless, and the wear on your clutch disk, pressure plate, release bearing, and flywheel will be minimized.
If properly designed (sufficient size and clamping pressure, etc.), and properly installed with no defects (correct torque, non-faulty equipment, alignment, etc.), then the next, and most important, factor to the life of the clutch assembly is the operator.
THERE IS ABSOLUTELY NO REASON WHY A CLUTCH CANNOT LAST THE LIFE OF THE ENGINE UNDER NORMAL DRIVING CONDITIONS.
When I speak of engine life here, I am referring to life before a serious teardown or part replacement such as a timing chain (200,000+ miles) or headwork. If you cannot get at least 100,000 miles out of a clutch, you are doing something terribly wrong. Obviously, racing and other extreme conditions such as towing constitute a whole different approach and, as such, do not come under this.
Don'ts:
Do not use any more engine speed (RPMs) than absolutely necessary to get the car rolling in first gear.
Do not hold the car on a hill with the clutch.
Do not wait for a traffic light to turn green with the transmission in gear and the clutch depressed.
Do not rest your foot on the clutch while driving.
Do not ride the clutch in any gear (obviously you will to a small degree in first to start off).
Do not down shift by just removing your foot from the gas, moving the shifter into a lower gear, then releasing the clutch slowly.
Do's
Start off smoothly and with low engine speed, and shift in such a manner that if you had a passenger on board, they would not even notice the shifts.
Hold the car on hills with the brakes.. that's what brakes are for. NEVER hold a car on a hill with the clutch. The amount of heat generated by doing this is incredible.
While waiting for a light to change or while sitting in heavy traffic, put the transmission in neutral and get your foot completely off of the clutch petal. Leaving it in gear for extended periods heats up and shortens the life of the release bearing. The normal condition of a clutch is fully engaged so it stands to reason that's where it should be most of the time.
Resting your foot on the clutch petal while driving engages the release bearing.. see above.
Avoid riding the clutch as much as is humanly possible. You will extend its life significantly.
If you do not know how to properly downshift, DON’T. Use the brakes (should do this anyway), and avoid downshifting any more than necessary. Improper downshifting is analogous to riding the clutch because that is what you are actually doing. Learn how to properly downshift first and save yourself the frustration of premature clutch failure.
Clutches are wear items, heavily affected by heat caused by friction. In a front wheel drive car, they are costly to replace, so unless you like shelling out a lot of money periodically for the replacement of these components, learn the correct way. Learn it until it becomes second nature like breathing.
Downshifting
Ah yes, downshifting. If I had to name just one facet of manual transmission errors-of-operation, this would probably be it.
To understand how to operate a manual transmission, you have to know how the clutch assembly and transmission work, and I am going to take the assumption that most do on this forum. I will only clarify synchronizers. They serve to match the speed of the gears in the transmission as the shifter is moved to a given gear. Now for downshifting.
Let's say you are in fourth gear and you are approaching a stop sign, so you decide to downshift from fourth gear into third. What most people do is just remove their foot from the throttle, depress the clutch while moving the shifter from fourth to third, then start releasing the clutch slowly until they achieve full engagement. If you do this, what you are actually doing is riding the clutch in third gear. After all, the engine has returned to idle (or close to it), you get into third, then just ease the clutch out which pulls the engine from idle up to the RPM's at which it will operate at whatever speed you are traveling in third gear. Here is the correct way to do this in steps that I will break down in a moment.
Raise your foot off of the throttle.
Depress the clutch.
Start the shifter up into third.
As you pass through the neutral gate, let the clutch out a bit (doesn't have to be all the way) while at the same time blipping the throttle to increase engine speed BEYOND that which it will operate in the chosen lower gear.
Depress the clutch again.
Engage the chosen lower gear.
Let the clutch out while adding throttle.
As the engine RPM's decrease they will be met by the engaging clutch and opening throttle.
This should be a simple, smooth, fluid motion and you will know you've done it right if there is no jerking as the clutch comes out in the last step. Now for some details.
As you move into the neutral gate with your foot off of the throttle, the engine RPM's will be returning to idle. This is the point at which you want to blip the throttle a bit while at the same time engaging the clutch some. You want to get the engine turning faster than it will when you are in the lower gear you have chosen. The reason is that you want to spin the gears up to a speed that equals that at which they will be operating when you finally release the clutch in your downshift. If you do this right, there is no clutch slippage because the engine and the gears in the transmission will be spinning at the same or nearly the same RPM's. No slippage means you will get into gear with full engagement of the clutch sooner and with virtually no wear. To best understand this, you really need to know how a clutch assembly and transmission work together to deliver power from the engine to the drive wheels.
This takes a lot of practice, but if you get it down, you will be heads and shoulders above just about anyone else who drives a car with a manual transmission. You will begin to notice the mistakes other are making when they drive. Learn from their mistakes and it will both save you money and make you a far better driver.
So it's in with the clutch, start the shifter into the chosen lower gear, while passing through the neutral gate, blip the throttle and at the same time engage the clutch a bit to spin up the gears, then back in with the clutch as you get into the chosen gear, then finally release the clutch in one smooth operation.
Here's another little tip. Say you are waiting at a light for the green and your transmission is in neutral like it should be with your foot completely off of the clutch petal. When the light turns green, instead of just depressing the clutch and pushing the shifter up into first, pull the shifter partially into a higher gear first, such as second or third. The gears in those selections are not spinning as fast as the gears in first. By starting the shifter into a higher gear before you go to into first gear, you will cause less wear on the synchronizers and they will last far longer because they do not have to stop gears which are spinning at a higher speed. For cars which do not have synchronized reverse, definitely do this and you will not experience the grinding affect when shifting into reverse.
Say you are driving normally, shifting up through the gears to the one in which you wish to be for cruising. As you disengage the clutch and move the shifter to the next higher gear, you might notice a slight resistance just before you finish the shift. What you feel is the synchronizer for that gear forcing the drive gear(s) from the input shaft and the gears selected to "mesh". That is to say, their speeds are forced to equalize so that as they engage, there is no grinding and no damage to the gear teeth. That said, we can move to double clutching.
Instead of going right into first as the light starts to go green, try starting the shifter into second gear.. don't have to go all the way into gear, though it won't hurt. This slows the gears down just as though you had gone on into first, but it's much easier on the synchronizers. And you won't get the "crunch" you mentioned when you have to move quickly.
To prevent rollback; practice, practice, practice, practice.
One way to do this is to find a nice little hill someplace where you won't be a bother to anyone. Take along some masking tape and mark off two sections with the tape a foot apart. Your goal is to keep the car from coasting back more than 1 foot.. of course you do not use the clutch to hold the car.. use the brakes. As you learn to do this, find another hill a little steeper. And so on, and so on.
And remember. Just because someone has been driving a manual transmission for years does not mean they know how to do it correctly. Don't absorb bad habits.
================================================== ========
What follows is a collection of writings which I have posted at various times on this website in an effort to help answer some questions regarding the proper manner in which a manual transmission should be operated. While there are certainly many ways to drive a car with a manual transmission, there is really only one correct way. I was most fortunate to have learned these techniques while I was still in my teenage years. In so doing, I was able to avoid developing entrenched habits before they became really bad habits and difficult to correct. It is my hope that this helps you learn what I have learned and perfected over the years. If you do, you will reap the rewards, both financial and in the knowledge that you have mastered a technique that few do in their lifetimes. Have fun!
Under normal driving situations (not racing), when you start out from a standing start, you do so with the lowest possible RPMs, get the clutch out to full engagement as soon as you can while adding throttle. If you do this correctly, the transition will be smooth and seamless, and the wear on your clutch disk, pressure plate, release bearing, and flywheel will be minimized.
If properly designed (sufficient size and clamping pressure, etc.), and properly installed with no defects (correct torque, non-faulty equipment, alignment, etc.), then the next, and most important, factor to the life of the clutch assembly is the operator.
THERE IS ABSOLUTELY NO REASON WHY A CLUTCH CANNOT LAST THE LIFE OF THE ENGINE UNDER NORMAL DRIVING CONDITIONS.
When I speak of engine life here, I am referring to life before a serious teardown or part replacement such as a timing chain (200,000+ miles) or headwork. If you cannot get at least 100,000 miles out of a clutch, you are doing something terribly wrong. Obviously, racing and other extreme conditions such as towing constitute a whole different approach and, as such, do not come under this.
Don'ts:
Do not use any more engine speed (RPMs) than absolutely necessary to get the car rolling in first gear.
Do not hold the car on a hill with the clutch.
Do not wait for a traffic light to turn green with the transmission in gear and the clutch depressed.
Do not rest your foot on the clutch while driving.
Do not ride the clutch in any gear (obviously you will to a small degree in first to start off).
Do not down shift by just removing your foot from the gas, moving the shifter into a lower gear, then releasing the clutch slowly.
Do's
Start off smoothly and with low engine speed, and shift in such a manner that if you had a passenger on board, they would not even notice the shifts.
Hold the car on hills with the brakes.. that's what brakes are for. NEVER hold a car on a hill with the clutch. The amount of heat generated by doing this is incredible.
While waiting for a light to change or while sitting in heavy traffic, put the transmission in neutral and get your foot completely off of the clutch petal. Leaving it in gear for extended periods heats up and shortens the life of the release bearing. The normal condition of a clutch is fully engaged so it stands to reason that's where it should be most of the time.
Resting your foot on the clutch petal while driving engages the release bearing.. see above.
Avoid riding the clutch as much as is humanly possible. You will extend its life significantly.
If you do not know how to properly downshift, DON’T. Use the brakes (should do this anyway), and avoid downshifting any more than necessary. Improper downshifting is analogous to riding the clutch because that is what you are actually doing. Learn how to properly downshift first and save yourself the frustration of premature clutch failure.
Clutches are wear items, heavily affected by heat caused by friction. In a front wheel drive car, they are costly to replace, so unless you like shelling out a lot of money periodically for the replacement of these components, learn the correct way. Learn it until it becomes second nature like breathing.
Downshifting
Ah yes, downshifting. If I had to name just one facet of manual transmission errors-of-operation, this would probably be it.
To understand how to operate a manual transmission, you have to know how the clutch assembly and transmission work, and I am going to take the assumption that most do on this forum. I will only clarify synchronizers. They serve to match the speed of the gears in the transmission as the shifter is moved to a given gear. Now for downshifting.
Let's say you are in fourth gear and you are approaching a stop sign, so you decide to downshift from fourth gear into third. What most people do is just remove their foot from the throttle, depress the clutch while moving the shifter from fourth to third, then start releasing the clutch slowly until they achieve full engagement. If you do this, what you are actually doing is riding the clutch in third gear. After all, the engine has returned to idle (or close to it), you get into third, then just ease the clutch out which pulls the engine from idle up to the RPM's at which it will operate at whatever speed you are traveling in third gear. Here is the correct way to do this in steps that I will break down in a moment.
Raise your foot off of the throttle.
Depress the clutch.
Start the shifter up into third.
As you pass through the neutral gate, let the clutch out a bit (doesn't have to be all the way) while at the same time blipping the throttle to increase engine speed BEYOND that which it will operate in the chosen lower gear.
Depress the clutch again.
Engage the chosen lower gear.
Let the clutch out while adding throttle.
As the engine RPM's decrease they will be met by the engaging clutch and opening throttle.
This should be a simple, smooth, fluid motion and you will know you've done it right if there is no jerking as the clutch comes out in the last step. Now for some details.
As you move into the neutral gate with your foot off of the throttle, the engine RPM's will be returning to idle. This is the point at which you want to blip the throttle a bit while at the same time engaging the clutch some. You want to get the engine turning faster than it will when you are in the lower gear you have chosen. The reason is that you want to spin the gears up to a speed that equals that at which they will be operating when you finally release the clutch in your downshift. If you do this right, there is no clutch slippage because the engine and the gears in the transmission will be spinning at the same or nearly the same RPM's. No slippage means you will get into gear with full engagement of the clutch sooner and with virtually no wear. To best understand this, you really need to know how a clutch assembly and transmission work together to deliver power from the engine to the drive wheels.
This takes a lot of practice, but if you get it down, you will be heads and shoulders above just about anyone else who drives a car with a manual transmission. You will begin to notice the mistakes other are making when they drive. Learn from their mistakes and it will both save you money and make you a far better driver.
So it's in with the clutch, start the shifter into the chosen lower gear, while passing through the neutral gate, blip the throttle and at the same time engage the clutch a bit to spin up the gears, then back in with the clutch as you get into the chosen gear, then finally release the clutch in one smooth operation.
Here's another little tip. Say you are waiting at a light for the green and your transmission is in neutral like it should be with your foot completely off of the clutch petal. When the light turns green, instead of just depressing the clutch and pushing the shifter up into first, pull the shifter partially into a higher gear first, such as second or third. The gears in those selections are not spinning as fast as the gears in first. By starting the shifter into a higher gear before you go to into first gear, you will cause less wear on the synchronizers and they will last far longer because they do not have to stop gears which are spinning at a higher speed. For cars which do not have synchronized reverse, definitely do this and you will not experience the grinding affect when shifting into reverse.
Say you are driving normally, shifting up through the gears to the one in which you wish to be for cruising. As you disengage the clutch and move the shifter to the next higher gear, you might notice a slight resistance just before you finish the shift. What you feel is the synchronizer for that gear forcing the drive gear(s) from the input shaft and the gears selected to "mesh". That is to say, their speeds are forced to equalize so that as they engage, there is no grinding and no damage to the gear teeth. That said, we can move to double clutching.
Instead of going right into first as the light starts to go green, try starting the shifter into second gear.. don't have to go all the way into gear, though it won't hurt. This slows the gears down just as though you had gone on into first, but it's much easier on the synchronizers. And you won't get the "crunch" you mentioned when you have to move quickly.
To prevent rollback; practice, practice, practice, practice.
One way to do this is to find a nice little hill someplace where you won't be a bother to anyone. Take along some masking tape and mark off two sections with the tape a foot apart. Your goal is to keep the car from coasting back more than 1 foot.. of course you do not use the clutch to hold the car.. use the brakes. As you learn to do this, find another hill a little steeper. And so on, and so on.
07-06-2010, 02:17 PM
#3
Short version: Option B is "correct" because it saves wear on the synchros as well as the clutch. Option A is better than the way most people I've seen downshift, which is to downshift without blipping the throttle at all. It's a great way to lurch the car around, make your passenger spill his beer ( 
), and wear out the clutch. Option A will avoid wearing out the clutch, but will not save any wear and tear on the synchros.
), and wear out the clutch. Option A will avoid wearing out the clutch, but will not save any wear and tear on the synchros.
07-06-2010, 02:42 PM
#4
Registered Member
Short version: Option B is "correct" because it saves wear on the synchros as well as the clutch. Option A is better than the way most people I've seen downshift, which is to downshift without blipping the throttle at all. It's a great way to lurch the car around, make your passenger spill his beer ( ), and wear out the clutch. Option A will avoid wearing out the clutch, but will not save any wear and tear on the synchros.
), and wear out the clutch. Option A will avoid wearing out the clutch, but will not save any wear and tear on the synchros.
True.. all of it.
07-06-2010, 02:44 PM
#5
Registered Member
Been reading on a few forums and it seems there are lots of different opinions on what is the 'correct' way to rev match when downshifting gears. Here are the two main techniques that I've gathered when downshifting from ie. 4th to 3rd gear:
A: While in 4th gear, clutch in (disengage clutch), shift to 3rd gear, blip the throttle to anticipated RPM, clutch out (engage clutch)
B: While in 4th gear, clutch in, shift to Neutral, clutch out, blip throttle to anticipated RPM, clutch in, shift to 3rd gear, clutch out
As I understand, technique A is rev match downshifting while technique B is the same thing with the addition of double clutching. As well, people say that B is the most proper way to rev match downshift because it engages certain parts of the transmission (ie. syncros) that A does not.
For a 3rd gen 6MT, what would be you consider to be the most appropriate way to rev match down shift and why?
A: While in 4th gear, clutch in (disengage clutch), shift to 3rd gear, blip the throttle to anticipated RPM, clutch out (engage clutch)
B: While in 4th gear, clutch in, shift to Neutral, clutch out, blip throttle to anticipated RPM, clutch in, shift to 3rd gear, clutch out
As I understand, technique A is rev match downshifting while technique B is the same thing with the addition of double clutching. As well, people say that B is the most proper way to rev match downshift because it engages certain parts of the transmission (ie. syncros) that A does not.
For a 3rd gen 6MT, what would be you consider to be the most appropriate way to rev match down shift and why?
07-06-2010, 06:03 PM
#6
Advanced
Thread Starter
Now that leads to my next question: With a car containing a modern manual transmission such as ours, is the amount of wear and tear saved by double clutch rev match downshifting significant, especially when using this technique on a daily basis?
07-06-2010, 09:09 PM
#7
Didn't read all the posts, but one main ingredient is missing when using B, which I think is ridiculous in our day to day driving, clutch out in neutral, blip the throttle and by the time you push the clutch in, shift into the lower gear, the trans RPM's have already changed so the technique has gone out the window. Not only that, this also creates extra wear on the clutch components, and this is why synchronizers are used. You certainly don't use this procedure when up shifting so you’re relying on the syncros, so why the difference when downshifting. Match the engine RPM's. To me if rev matching is done properly no need to double clutch.
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07-06-2010, 09:24 PM
#8
Registered Member
Didn't read all the posts, but one main ingredient is missing when using B, which I think is ridiculous in our day to day driving, clutch out in neutral, blip the throttle and by the time you push the clutch in, shift into the lower gear, the trans RPM's have already changed so the technique has gone out the window. Not only that, this also creates extra wear on the clutch components, and this is why synchronizers are used. You certainly don't use this procedure when up shifting so you’re relying on the syncros, so why the difference when downshifting. Match the engine RPM's. To me if rev matching is done properly no need to double clutch.
And double clutching reduces wear across the board to all components. When done correctly, a passenger would be oblivious to the downshift. I do this all the time.
Incidentally, synchronized manual transmissions have been around for quite a while... since 1929 (Cadillac).
07-06-2010, 09:28 PM
#9
Registered Member
Ok that's what I thought. So essentially doing technique A is a half-assed way of rev match downshifting while technique B is the most correct way.
Now that leads to my next question: With a car containing a modern manual transmission such as ours, is the amount of wear and tear saved by double clutch rev match downshifting significant, especially when using this technique on a daily basis?
Now that leads to my next question: With a car containing a modern manual transmission such as ours, is the amount of wear and tear saved by double clutch rev match downshifting significant, especially when using this technique on a daily basis?
As for wear in the TL? Well there have been enough complaints about the 3rd gear issue that I suspect if one had done this from day one, perhaps they may not have had any problems. I am one of these drivers.
07-06-2010, 09:30 PM
#10
thats a whole lotta typing for something pretty simple.
blip throttle to match revs to wanted gear, double clutch that biatch into gear and you're off.
i never double clutch when i upshift but find that the honda transmissions downshift better with the double action.
blip throttle to match revs to wanted gear, double clutch that biatch into gear and you're off.
i never double clutch when i upshift but find that the honda transmissions downshift better with the double action.
07-06-2010, 09:35 PM
#11
Rev High; Drive Happy
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I don't know if it's just me as I've gotten really used to driving a manual car but...
It seems that there are times the car blips the revs up by 500-1000 RPMs.
Either that or I'm unintentionally doing it.
If it is that case: it seems that the TL helps you rev-match [as it seems that 1 gear lower is usually about 1000RPMs more].
My general idea is that I would rev-match to 1 gear lower... and double clutch when going 2 or more gears lower.
It seems that there are times the car blips the revs up by 500-1000 RPMs.
Either that or I'm unintentionally doing it.
If it is that case: it seems that the TL helps you rev-match [as it seems that 1 gear lower is usually about 1000RPMs more].
My general idea is that I would rev-match to 1 gear lower... and double clutch when going 2 or more gears lower.
07-06-2010, 09:39 PM
#12
Registered Member
Double clutching on upshifts is not only something to avoid (except under specific conditions), it can be injurious to your car.
07-06-2010, 10:08 PM
#14
Registered Member
Since you are blipping the throttle to raise engine speed and your next higher gear is going to have the engine turning at a lower engine speed, you either have to wait for things to match or you complete the shift to the tune of a jolt to your drive train.
07-07-2010, 07:05 AM
#16
I have to disagree with this my friend. Rev-matching reduces clutch component wear because the drive wheels do not have to pull engine speed back up from its fall towards idle. Double clutching takes this further by spinning up the lay shaft in preparation of the downshift. So you get the benefits of rev-matching AND those of matching shaft speeds to reduce synchronizer wear.
And double clutching reduces wear across the board to all components. When done correctly, a passenger would be oblivious to the downshift. I do this all the time.
Incidentally, synchronized manual transmissions have been around for quite a while... since 1929 (Cadillac).
And double clutching reduces wear across the board to all components. When done correctly, a passenger would be oblivious to the downshift. I do this all the time.
Incidentally, synchronized manual transmissions have been around for quite a while... since 1929 (Cadillac).
Just like the heel/toe method when racing, enter a corner, left foot on clutch, right on brake, blip the throttle while foot still on brake, then down shift and there will be no speed reduction/increase the second the disc makes contact with the flywheel/pressure plate. I've seen guys downshift and actually break the rear wheels loose because they don't know, or haven't learned the procedure. Do it right and no problem.
If a guy/gal doesn't know his car/engine when they double shift, how will they know the RPM's needed for the lower gear? I’ve can see it now, put it in neutral rev the heck out of the engine, drop it in a lower gear and the car will jump ahead as the RPM's are screaming.
As we have a difference of opinion, I've said my peace and given the explanation, as have you, now it's up to the OP, and others to make the decision.
Just saw this. On occasion,if shifting very slowly, the engine RPM's will drop as soon as the cluch is disengaged and the foot comes off the gas pedal, so blip the throttle to match the RPM's to the net higher gear. Once one becomes proficient, you can shift gears quickly and the RPM's won't fall or in all out competition, with the gas pedal held to the floor, but never tried it in an Acura, so don't know the results with the electronics/clutch assembly.
Last edited by Turbonut; 07-07-2010 at 07:14 AM.
07-07-2010, 07:48 AM
#17
Registered Member
The only time this makes sense is if you hold up on your shift deliberately, or somehow your timing gets messed up. Other than that, the normal fall of the engine's speed is factored into your upshift and all is well.
07-07-2010, 07:59 AM
#18
Registered Member
Sorry, but it can't possibly reduce wear across the board as the throwout bearing and hydraulics are being used twice as much. Also, if the rev matching is done properly you won't need to double clutch as the engine rpm's are in sync with the drive train when the clutch is released and in a lower gear. Just got to know your car and the sound of the engine, rpm's needed to obtain that speed in a particular gear, then when down shifting the RPM's will match the wheel speed.
Just like the heel/toe method when racing, enter a corner, left foot on clutch, right on brake, blip the throttle while foot still on brake, then down shift and there will be no speed reduction/increase the second the disc makes contact with the flywheel/pressure plate. I've seen guys downshift and actually break the rear wheels loose because they don't know, or haven't learned the procedure. Do it right and no problem.
If a guy/gal doesn't know his car/engine when they double shift, how will they know the RPM's needed for the lower gear? I’ve can see it now, put it in neutral rev the heck out of the engine, drop it in a lower gear and the car will jump ahead as the RPM's are screaming.
As we have a difference of opinion, I've said my peace and given the explanation, as have you, now it's up to the OP, and others to make the decision.
Just saw this. On occasion,if shifting very slowly, the engine RPM's will drop as soon as the cluch is disengaged and the foot comes off the gas pedal, so blip the throttle to match the RPM's to the net higher gear. Once one becomes proficient, you can shift gears quickly and the RPM's won't fall or in all out competition, with the gas pedal held to the floor, but never tried it in an Acura, so don't know the results with the electronics/clutch assembly.
Just like the heel/toe method when racing, enter a corner, left foot on clutch, right on brake, blip the throttle while foot still on brake, then down shift and there will be no speed reduction/increase the second the disc makes contact with the flywheel/pressure plate. I've seen guys downshift and actually break the rear wheels loose because they don't know, or haven't learned the procedure. Do it right and no problem.
If a guy/gal doesn't know his car/engine when they double shift, how will they know the RPM's needed for the lower gear? I’ve can see it now, put it in neutral rev the heck out of the engine, drop it in a lower gear and the car will jump ahead as the RPM's are screaming.
As we have a difference of opinion, I've said my peace and given the explanation, as have you, now it's up to the OP, and others to make the decision.
Just saw this. On occasion,if shifting very slowly, the engine RPM's will drop as soon as the cluch is disengaged and the foot comes off the gas pedal, so blip the throttle to match the RPM's to the net higher gear. Once one becomes proficient, you can shift gears quickly and the RPM's won't fall or in all out competition, with the gas pedal held to the floor, but never tried it in an Acura, so don't know the results with the electronics/clutch assembly.
Here's an example. Suppose you were driving a truck with no synchronzers and rev matched a downshift. When you tried to perform the shift, the dog teeth would grind like crazy, thereby preventing the shift from completing. Now if you double clutch this shift, the dog teeth will insert into their mating slots and you will be fine. The introduction of synchronzers into this adds clutching to this action. In other words, they are doing the shaft speed matching. In doing so, there is some wear which over time, will require a transmission rebuild.
Rev matching extends the life of the clutch. Double clutching extends the life of both the clutch and the synchronzers.
07-07-2010, 10:13 AM
#19
Yes, you are correct, this double clutching method was utilized years ago when the transmission didn't have syncros, but now we are driving vehicles that are quite forgiving. Using your example, if in neutral and you double clutch, push the clutch in then shift into the lower gear, how will the RPM's stay at the same level as they were when in neutral. They won't, they will fall as you shift from neutral, unless someone is going to hold the RPM's at a given level after shifting from neutral, and this would be quite difficult if you need to use the brakes, and once again if one's not able to rev match when downshifting, they certainly won't know the correct RPM to select when double clutching. On acceleration, every upshift will utilize the syncros, so why even concern yourself about the possible wear on the syncros when downshifting? Also, when the clutch is disengaged, the only part of the trans that slows is the main drive/input shaft, as the tailshaft is still turning at d/s speed, therefore this is the only item you're trying to eqalize with engine matching revs so as when the clutch is engaged the transition will be not noticeable in feel.
07-07-2010, 10:53 AM
#20
Advanced
I remember hearing about double clutching a long time ago but never really understood it until reading here recently. I've been driving mostly standards for the past 17 years and in the past month I've been trying this technique At first it seemed as crazy as a 3.17$ paper bill, I was asking "how can anyone do this all the time." The first few days were really hard but now I've become much better at it.
It's not natural feeling for me yet but when you get it right, you can feel how smooth everything engages. So easy on the drivetrain when done right.
It's not natural feeling for me yet but when you get it right, you can feel how smooth everything engages. So easy on the drivetrain when done right.
07-07-2010, 11:26 AM
#22
I've been trying this too. The double-clutch is so awkward to me. It's like playing a set of drums, which I was never good at. Getting the timing right between what your left and right foot does and your steering hand and your shifting hand. All four limbs are doing something at the same time. I try though.
I have been trying to heel-toe shift and I simply can't do it. Either my foot doesn't bend enough or the accelerator pedal is too deep compared to the brake pedal. Everytime I try I accidentally apply the brake harder and my heel doesn't come close to the accelerator. What can be done to fix this?
I have been trying to heel-toe shift and I simply can't do it. Either my foot doesn't bend enough or the accelerator pedal is too deep compared to the brake pedal. Everytime I try I accidentally apply the brake harder and my heel doesn't come close to the accelerator. What can be done to fix this?
07-07-2010, 01:26 PM
#24
Advanced
Thread Starter
This makes perfect sense.
Now what if you're not perfect at your rev matching in the amount of throttle blip? Say you're off by +/- 500 rpm, is there the potential that this would somehow cause unintentional harm?
07-07-2010, 01:29 PM
#25
Advanced
Thread Starter
I've been trying this too. The double-clutch is so awkward to me. It's like playing a set of drums, which I was never good at. Getting the timing right between what your left and right foot does and your steering hand and your shifting hand. All four limbs are doing something at the same time. I try though.
I have been trying to heel-toe shift and I simply can't do it. Either my foot doesn't bend enough or the accelerator pedal is too deep compared to the brake pedal. Everytime I try I accidentally apply the brake harder and my heel doesn't come close to the accelerator. What can be done to fix this?
I have been trying to heel-toe shift and I simply can't do it. Either my foot doesn't bend enough or the accelerator pedal is too deep compared to the brake pedal. Everytime I try I accidentally apply the brake harder and my heel doesn't come close to the accelerator. What can be done to fix this?
07-07-2010, 02:07 PM
#26
Registered Member
Your shifting will be jerky because of the variance of engine speed versus wheel speed. Prolonged periods of this can cause harm to components as well. It is a timing thing and I suggest for those who are just starting to do this to use your tach. Our TL's are pretty quiet so it is more difficult to rely on engine sound for this technique. After time, you'll start doing this as a matter of habit so using the tach will become less of a concern.
07-07-2010, 02:15 PM
#27
Registered Member
Yes, you are correct, this double clutching method was utilized years ago when the transmission didn't have syncros, but now we are driving vehicles that are quite forgiving. Using your example, if in neutral and you double clutch, push the clutch in then shift into the lower gear, how will the RPM's stay at the same level as they were when in neutral. They won't, they will fall as you shift from neutral, unless someone is going to hold the RPM's at a given level after shifting from neutral, and this would be quite difficult if you need to use the brakes, and once again if one's not able to rev match when downshifting, they certainly won't know the correct RPM to select when double clutching. On acceleration, every upshift will utilize the syncros, so why even concern yourself about the possible wear on the syncros when downshifting? Also, when the clutch is disengaged, the only part of the trans that slows is the main drive/input shaft, as the tailshaft is still turning at d/s speed, therefore this is the only item you're trying to eqalize with engine matching revs so as when the clutch is engaged the transition will be not noticeable in feel.
o Remove your foot from the throttle while depressing the clutch.
o Start the shift to 3rd gear but pause a moment in neutral.
o While pausing in neutral, blip the throttle to raise engine speed above that point where it will need to be in 3rd gear when you release your clutch. When you do this, also engage the clutch.
o Depress the clutch again and complete the shift into 3rd gear.
o Release the clutch.
If performed correctly, the downshift will be smooth and seemless and not detectable by passengers in your car. As engine speed falls off from the blip in neutral, it will get to a point where it needs to be for 3rd gear and that is when you release the clutch. Once this becomes second nature, there is no holding of the clutch to wait for falling RPM's or anything of the sort. It will be a natural and normal behavior and will significantly increase synchronizer and clutch life.
07-07-2010, 02:16 PM
#28
Registered Member
Heel-and-toeing is a technique which I have never mastered. I know how to do it, but I am not consistent in smoothness or procedure, so I stick to double clutching my downshifts in the normal fashion.
07-07-2010, 02:17 PM
#29
Team Owner
In real life, maybe I'm just slower than most but double clutching is just too slow for me.
There's no doubt it saves the syncros. I had to do it whenever I drove my friend's BMW because the 2nd gear syncro was completely gone to the point you could not complete a shift no matter how slowly without double clutching.
I always rev match when downshifting, to me it's so lazy and sloppy to let the clutch spin the rpms up. I pride myself on downshifts that can't be felt by the passengers. The only thing I hate about modern cars is the slow revving and delayed nature of the revs. My friend's turbo Porsche has the potential to make you look like a pro driver. It revs so amazingly quick that you can be on the brakes very hard and pop off 3 very quick rev matched downshifts like a pro.
Some cars tend to let the rpms hang during upshifts which I hate. Some cars have a delay when you hit the throttle so you're compensating by hitting the throttle slightly before you even disengage the clutch. Some rev so slow that you automatically hit the throttle to the floor during rev matching to avoid a 5 second downshift.
There's no doubt it saves the syncros. I had to do it whenever I drove my friend's BMW because the 2nd gear syncro was completely gone to the point you could not complete a shift no matter how slowly without double clutching.
I always rev match when downshifting, to me it's so lazy and sloppy to let the clutch spin the rpms up. I pride myself on downshifts that can't be felt by the passengers. The only thing I hate about modern cars is the slow revving and delayed nature of the revs. My friend's turbo Porsche has the potential to make you look like a pro driver. It revs so amazingly quick that you can be on the brakes very hard and pop off 3 very quick rev matched downshifts like a pro.
Some cars tend to let the rpms hang during upshifts which I hate. Some cars have a delay when you hit the throttle so you're compensating by hitting the throttle slightly before you even disengage the clutch. Some rev so slow that you automatically hit the throttle to the floor during rev matching to avoid a 5 second downshift.
07-07-2010, 02:20 PM
#30
Team Owner
I know it's illegal but I do it when barefoot. With my size 13s I feel very clumsy when attempting it with shoes on. I have a worn out old set of shoes I've used at the dragstrip for years and more recently at the race track. They're so worn and thin on the bottom, I can feel the pedals almost like being barefoot.
07-07-2010, 02:20 PM
#31
Registered Member
Gentlemen;
There are some differences of opinion as to whether or not double clutching is really necessary and whether or not one should bother with it. From my perspective, whether or not someone chooses to learn and master this technique is strictly their business. The way I see it is it's their money and their car. For those who want to adopt this technique as part of their manual transmission operational knowledge, I think that is certainly a big plus. But again, it's their decision to take. I know it works and I also know the pluses far outweigh any negatives. So y'all can choose as you see fit.
There are some differences of opinion as to whether or not double clutching is really necessary and whether or not one should bother with it. From my perspective, whether or not someone chooses to learn and master this technique is strictly their business. The way I see it is it's their money and their car. For those who want to adopt this technique as part of their manual transmission operational knowledge, I think that is certainly a big plus. But again, it's their decision to take. I know it works and I also know the pluses far outweigh any negatives. So y'all can choose as you see fit.
Last edited by SouthernBoy; 07-07-2010 at 02:30 PM.
07-07-2010, 02:29 PM
#33
Registered Member
In real life, maybe I'm just slower than most but double clutching is just too slow for me.
There's no doubt it saves the syncros. I had to do it whenever I drove my friend's BMW because the 2nd gear syncro was completely gone to the point you could not complete a shift no matter how slowly without double clutching.
I always rev match when downshifting, to me it's so lazy and sloppy to let the clutch spin the rpms up. I pride myself on downshifts that can't be felt by the passengers. The only thing I hate about modern cars is the slow revving and delayed nature of the revs. My friend's turbo Porsche has the potential to make you look like a pro driver. It revs so amazingly quick that you can be on the brakes very hard and pop off 3 very quick rev matched downshifts like a pro.
Some cars tend to let the rpms hang during upshifts which I hate. Some cars have a delay when you hit the throttle so you're compensating by hitting the throttle slightly before you even disengage the clutch. Some rev so slow that you automatically hit the throttle to the floor during rev matching to avoid a 5 second downshift.
There's no doubt it saves the syncros. I had to do it whenever I drove my friend's BMW because the 2nd gear syncro was completely gone to the point you could not complete a shift no matter how slowly without double clutching.
I always rev match when downshifting, to me it's so lazy and sloppy to let the clutch spin the rpms up. I pride myself on downshifts that can't be felt by the passengers. The only thing I hate about modern cars is the slow revving and delayed nature of the revs. My friend's turbo Porsche has the potential to make you look like a pro driver. It revs so amazingly quick that you can be on the brakes very hard and pop off 3 very quick rev matched downshifts like a pro.
Some cars tend to let the rpms hang during upshifts which I hate. Some cars have a delay when you hit the throttle so you're compensating by hitting the throttle slightly before you even disengage the clutch. Some rev so slow that you automatically hit the throttle to the floor during rev matching to avoid a 5 second downshift.
07-07-2010, 02:33 PM
#34
Team Owner
Gentlemen;
There are some differences of opinion as to whether or not double clutching is really necessary and whether or not one should bother with it. From my perspective, whether or not someone chooses to learn and master this technique is strictly their business. The way I see it is it's their money and their car. For those who want to adopt this technique as part of their manual transmission operational knowledge, I think that is certainly a big plus. But again, it's their decision to take.
There are some differences of opinion as to whether or not double clutching is really necessary and whether or not one should bother with it. From my perspective, whether or not someone chooses to learn and master this technique is strictly their business. The way I see it is it's their money and their car. For those who want to adopt this technique as part of their manual transmission operational knowledge, I think that is certainly a big plus. But again, it's their decision to take.
I was extremely easy on my old Celica with a 5 speed. I took off at 1,000rpms and didn't give it more than about 15% throttle until the clutch was all the way engaged. I went 1-3-5 unless I needed to accelerate hard. Always rev matched but I didn't double clutch. At 228,000 miles, the original clutch was still fine. But this adds validity to your point, the second or third (can't remember which one) shift was starting to get hard to complete without grinding so the syncro was going out. Had I double clutched I'm sure it would be fine. But at 228,000 miles on the original clutch and trans, I got my money's worth.
Off topic but it finally died by getting stuck in 5th gear. I was finishing my commute and gettting off the freeway and it would not come out of 5th. Had to drive it home with 5 redlights and a few stop signs taking off in 5th. I did it as easy as humanly possible but it still required half throttle and a lot of slipping. Clutch held but the trans was $700 to replace so I sold it.
07-07-2010, 02:35 PM
#35
Team Owner
Hanging RPM's between upshifts is a designed in "feature" by some manufacturers.. and I would bet all who's cars do this. It is done to help burn off residual fuel (puddling) in the intake manifold and/or plenum to keep the EPA happy. It is a pain in the butt when upshifting and downright dangerous.
07-07-2010, 02:43 PM
#36
Registered Member
This what I discovered when I researched the reason for the significant throttle hang in my 2000 SVT Contour. I know our TL's do this very little compared to some cars.
07-07-2010, 03:45 PM
#37
If a guy/gal doesn't know his car/engine when they double shift, how will they know the RPM's needed for the lower gear? I’ve can see it now, put it in neutral rev the heck out of the engine, drop it in a lower gear and the car will jump ahead as the RPM's are screaming.
In my 2 manual-transmission cars, I can actually shift without the clutch (and without grinding) in all but 1st gear (obviously) because I know exactly what RPM's at a given speed each gear requires. This, btw, is how semi drivers do it, and if done properly, is the only way to avoid causing wear to either the clutch or the synchros.
BTW I drove an 05MT a few times and noticed the rev hang. It seemed to drop the revs to just about exactly where they needed to be for the next gear, assuming a reasonably quick shift. I always figured it was just a smooth-shifting assist feature built in by Acura.
07-08-2010, 11:36 AM
#39
Great thread!! I Learned alot as I continue to learn how to drive my first manual. The only thing that really annoys me is the rough acceleration from a stop usually only on slight inclines. I have the XLR8 engine damper which makes it a bit rougher but even with the stock I would get engine vibrations. Seems like its a choice between either over reving to limit engine torque and vibrations to the cabin, or normal gas/clutch engagement which torques the engine transfering vibrations to the cabin. Keep in mind this is starting out in first on a slight incline, on flat or down hill starting out is smooth as can be.
07-08-2010, 11:39 AM
#40
Ohh and another thing how do you all prepare to make a turn, say im going 45 in 4th gear and im coming up to a right turn in about 100 yards with a green light. Do you downshift at all before the turn or just make the turn then quickly rev match into 2nd or 3rd?