Downshifting
Oct 11, 2012, 09:54 AM
#31
Reading your comment over it seems you may I have thought my explanation was for heel-toe? My method for slowing-down/down-shifting does not include heel-toe. Initially I brake with right foot. Then I clutch in with left foot & rev with right foot. In heel-toe all of this is in one motion. You clutch, brake, and rev at essentially the same time.
My method is used for daily driving, not road racing.
Last edited by Kreeker; Oct 11, 2012 at 10:13 AM.
Oct 11, 2012, 10:11 AM
#32
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Oct 11, 2012, 10:25 AM
#33
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Buy an MR and like Sir Mix-A-Lot says F1 click click and see ya?
I keed I keed.
Heal and toe works like everyone says but I find the throttle lag this car has a bit annoying compared to my Nismo Z or any of my older cars. I'm thinking a tune and a lightweight flywheel will fix that.
I keed I keed.
Heal and toe works like everyone says but I find the throttle lag this car has a bit annoying compared to my Nismo Z or any of my older cars. I'm thinking a tune and a lightweight flywheel will fix that.
Oct 11, 2012, 10:48 AM
#34
If you are going slowly enough in 5th that you can go to 4th without over-reving your motor and without using your brakes, you are not on a race track. If you are, please move over, as there is a Miata trying to pass you...
If you are on the street, fine, you can do that but why? The concept of "heel/toe (something of a misnomer as you are really using your toe/ side of foot) is to be able to apply braking force, downshift, and get back on the throttle seamlessly to allow for a smooth braking and weight transition while you prepare the car to be in the right gear for track out (exiting the turn). Again, the benefit, not including just reducing the shock to your drivetrain, is to keep the car's weight and position where you want it.
The only time I can imagine not using the brakes and still using a rev matching technique is when you can use the front tires to scrub enough speed on turn-in to slow the car. Take the bowl at NJMP Lightning, hard in 5th to turn in, lift a bit, then use the front tire to scrub some speed, rev match to smooth into 4th and back on the gas through the apex and track out to the front straight. This works but that turn also requires trail braking at apex to bring the back end around, and that's not part of this lesson...
Oct 11, 2012, 06:49 PM
#35
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but is their really a right way to downshift??
i've been doing clutch, gear, gas instead of clutch, gas, gear. isn't the result the same? i'm gonna try your way on my way home today.
Oct 11, 2012, 06:58 PM
#36
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from wiki: http://en.wikipedia.org/wiki/Manual_...on#Synchromesh
"If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, which consists of a cone clutch and blocking ring. Before the teeth can engage, the cone clutch engages first, which brings the selector and gear to the same speed using friction. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or baulk) ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer.
The synchronizer[2] has to overcome the momentum of the entire input shaft and clutch disk when it is changing shaft rpm to match the new gear ratio. It can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate rev. matching with clutching can decrease the general change between layshaft and transmission and decrease synchro wear."
maybe i'm reading this incorrectly but it sounds to me like revmatch will decrease your synchro wear. so i'm right, if you dont revmatch your synchro will wear out prematurely. right??
i'm still learning. i'm no engineer or race car driver like rob.
Oct 12, 2012, 07:18 AM
#37
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^^^
Prematurely maybe if the parts are defective or if you're a really rough driver but factory wear rate yes.
By revmatching a synchronized tranny you will extend the life of the synchros because they won't have to work as hard to catch the differences in rotantional speed between engine and tranny.
Makes sense to me. Think about going up the stairs when you get to the top you're nice and tired. Now think about going up an escalator (while still climbing) you will be tired still yes but not as tired.
Ok bad analogy but you get the point
Prematurely maybe if the parts are defective or if you're a really rough driver but factory wear rate yes.
By revmatching a synchronized tranny you will extend the life of the synchros because they won't have to work as hard to catch the differences in rotantional speed between engine and tranny.
Makes sense to me. Think about going up the stairs when you get to the top you're nice and tired. Now think about going up an escalator (while still climbing) you will be tired still yes but not as tired.
Ok bad analogy but you get the point
Oct 12, 2012, 09:29 PM
#41
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You really don't need to HT when DD. Really. The only time I needed to HT was driving a Formula First (not Formula 1) around Brands Hatch circuit in UK. I kept locking the rear wheels into druids (a hairpin corner).
Oct 13, 2012, 05:14 AM
#42
it was my understanding that when you downshift without revmatch, you put stress on your synchro/ transmission component.
from wiki: http://en.wikipedia.org/wiki/Manual_...on#Synchromesh
"If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, which consists of a cone clutch and blocking ring. Before the teeth can engage, the cone clutch engages first, which brings the selector and gear to the same speed using friction. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or baulk) ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer.
The synchronizer[2] has to overcome the momentum of the entire input shaft and clutch disk when it is changing shaft rpm to match the new gear ratio. It can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate rev. matching with clutching can decrease the general change between layshaft and transmission and decrease synchro wear."
maybe i'm reading this incorrectly but it sounds to me like revmatch will decrease your synchro wear. so i'm right, if you dont revmatch your synchro will wear out prematurely. right??
i'm still learning. i'm no engineer or race car driver like rob.
from wiki: http://en.wikipedia.org/wiki/Manual_...on#Synchromesh
"If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, which consists of a cone clutch and blocking ring. Before the teeth can engage, the cone clutch engages first, which brings the selector and gear to the same speed using friction. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or baulk) ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer.
The synchronizer[2] has to overcome the momentum of the entire input shaft and clutch disk when it is changing shaft rpm to match the new gear ratio. It can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate rev. matching with clutching can decrease the general change between layshaft and transmission and decrease synchro wear."
maybe i'm reading this incorrectly but it sounds to me like revmatch will decrease your synchro wear. so i'm right, if you dont revmatch your synchro will wear out prematurely. right??
i'm still learning. i'm no engineer or race car driver like rob.
Also remind yourself according to this idea above, if you never boost high + rev your engine over 5000 rpm your engine life also will be MUCH longer.
Rob
Last edited by Robevo RS; Oct 13, 2012 at 05:38 AM.
Oct 13, 2012, 10:43 PM
#43
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Well, you'll hurt your motor. So, let's presume you are at 6600rpm in 5th on the back straight of Watkins Glen, push in the clutch, downshift to 4th, gas (to maybe 7800 rpm) to match it, and then just let the clutch out? The idea being to, what, shed speed with the engine torque alone? Say goodnight, Gracie.
If you are going slowly enough in 5th that you can go to 4th without over-reving your motor and without using your brakes, you are not on a race track. If you are, please move over, as there is a Miata trying to pass you...
If you are on the street, fine, you can do that but why? The concept of "heel/toe (something of a misnomer as you are really using your toe/ side of foot) is to be able to apply braking force, downshift, and get back on the throttle seamlessly to allow for a smooth braking and weight transition while you prepare the car to be in the right gear for track out (exiting the turn). Again, the benefit, not including just reducing the shock to your drivetrain, is to keep the car's weight and position where you want it.
The only time I can imagine not using the brakes and still using a rev matching technique is when you can use the front tires to scrub enough speed on turn-in to slow the car. Take the bowl at NJMP Lightning, hard in 5th to turn in, lift a bit, then use the front tire to scrub some speed, rev match to smooth into 4th and back on the gas through the apex and track out to the front straight. This works but that turn also requires trail braking at apex to bring the back end around, and that's not part of this lesson...
If you are going slowly enough in 5th that you can go to 4th without over-reving your motor and without using your brakes, you are not on a race track. If you are, please move over, as there is a Miata trying to pass you...
If you are on the street, fine, you can do that but why? The concept of "heel/toe (something of a misnomer as you are really using your toe/ side of foot) is to be able to apply braking force, downshift, and get back on the throttle seamlessly to allow for a smooth braking and weight transition while you prepare the car to be in the right gear for track out (exiting the turn). Again, the benefit, not including just reducing the shock to your drivetrain, is to keep the car's weight and position where you want it.
The only time I can imagine not using the brakes and still using a rev matching technique is when you can use the front tires to scrub enough speed on turn-in to slow the car. Take the bowl at NJMP Lightning, hard in 5th to turn in, lift a bit, then use the front tire to scrub some speed, rev match to smooth into 4th and back on the gas through the apex and track out to the front straight. This works but that turn also requires trail braking at apex to bring the back end around, and that's not part of this lesson...
