origionally posted by AWIDESUPIE:
Having a manual transmission automobile allows you to match engine/CRANK rpm with drivetrain mph/rpm at will.
Engine rpm is obviously determined by the tach. Drivetrain speed determined by speedometer ... whether your rolling or not .. and if so .. then how fast.
Crank rpm controlled by right foot/throttle .... drivetrain speed engaged by left foot/clutch.
The closer you can match crank rpm with drivetrain rpm/speed .. the smoother/more efficient engagement becomes.
Pretty simple.
While vehicle is at rest ... drivetrain speed is ~0mph/rpm ... and engine idle is at about 650-750rpm (slow). This relationship is similar in all manual transmission vehicles .. and allows one move forward/backward (gear dependent of course) without increasing engine rpm/throttle any more than idle. Yes, if you slip the clutch slowly enough ...the car will move forward (1)... or backwards (R) .. if there isn't too mutch incline resistance from either direction ... allowing the torque to move the vehicle. If there is too much resistance .. slightly increase throttle/crank rpm to allow engine torque to overcome drivetrain resistance.
The engine only stalls if the engine bites too quickly to something that is stationary (significantly slower drivetrain). The better biting clutch one has ... or the less slip the clutch provides .. the easier it becomes to stall/slow down the engine too much.
Many clutches provide for slipping (partial biting/engagement to drivetrain before becoming fully engaged) ... allowing it to graze the drivetrain for engagement and allow some of the drivetrain and crank kinetic/potential energy to be absorbed by the other.
What this means is that if, at idle and no rolling speed (for best illustration), you slip the clutch out slowy enough to gradually engage the stationary drivetrain ... if the crank energy/power can gradually be transfered to the drivetrain ... the car will move more quickly the more the drivetrain is fully engaged by crank until 100% kinetic/potential energy is tranfered (minus loss to heat energy). Not to confuse mater anymore .. but engagement of clutch could be quicker if the car was rolling fast enough but no too fast ... just slow roll ... for crank rpm/drivetrain relationship.
Things get a bit more tricky while driving at increased speed ... but it is still the same concept. Name of the game is to get a feel of clutch bite/feel ... crank rpm ... and drivetrain speed .... and reckognize their relationships.
As long as no modifications are performed .. and motin resistance form extremem wind or inclines/declines is not affecting relationships too much .... the engine rpm in each gear will always produce the same relatoinal drivetrain speed.
This means that you should be able to determine what crank rpm in what gear will provide for smoothest engagement by observing drivetrain speed .. and you will now how to make the engagement with the clutch by getting familiar with it's particular function traits (bite hard .. slips alot ... firm/soft pedal .. etc).
If exact relation cannot be determined ... it is always better to exceed necessary engine rpm and have the clutch slip a bit or wheels spin in relation to vehicle travel direction .... rather than to have drivetrain speed exceed its relation to crank rpm ... and have the engine go into shock as it is thrown violently towards redline ... and causes vehicle speed to decrease for a split second or more ... significantly .. causing immense shock to clutch/drivetrain rigidity etc.
For instance .... 2nd gear on a r154/7mgte combination in near stock form allows around 5 through 60-65mph ... 3rd about 25-30 through 80-85mph .... 4th about 30-40 through 120-125mph ... 5th about 40-45 through top speed.
If cruising on road at about 55mph in 5th gear ... you suddenly want to pass a vehicle by accelerating as quickly as possible.
You want to be in the lowest gear that allows you to travel at your current speed .. but you also want some room to run.
55mph may be a tough decision for downshift selection in a near stock combo ... because this is very close to top of 2nd (which SHOULD provide for best pull ... ***but**) and there is pleanty of good run room for 3rd .. and it may provide the best power-band.
If you wanted 2nd .... you would have to rev to right about redline and drop/slip the clutch (depending on clutch traits) .. b/c this is the relation to crank rpm in that gear at that speed.
I would choose 3rd gear, most likely, due to better power curve (b/c let's not forget the **but** .. the stock ct26 chokes top rpm flow .. so the tip range rpm of a second gear pull would probably be a less desireable part of the power-band).
To shift into third .. at 55mph ... I would approximate engine rpm relation t be about 3000-3500rpm .. so for a safe bet I may rev to about 500rpm over my estimate and dump/slip the clutch to engage for best pull.
If during any gear engagement I chose not to match crank rpm with drivetarin speed ... and let of the gas and attempted to engage drivetrain and throttle at the same time ... or even worse throttle slightly after drivetrain engagement .. that's when violent drivetrain shock is felt. BAD for vehicle components .. bad for attempted performance.
Same relationship for all relevant crank rpm/gear/drivetrain speed ratios. Once you figure em out ... and respect the control you have.... I dont think you'll ever want to drive an automatice again .. unless it's for leisure or straightline performance.
_______
The "art" of heel-toe shifting:
You may have seen it on picture in picture instructional video or driving videos simply showing where the car is going and what the driver is doing with their feet...
Heel to is uesed for optimal control of the vehicle while combining braking, shifting (99.99% down-shifting), and rev-matching (which I have explained in detail above).
The most optimal time for a heel-toe shift is when wanting to corner your vehicle as fast as possible .... for grip driving.
Appropriate way to tackle a turn for grip driving is to slow adequately before you enter the start of the turn, power/accelerate with throttle through the turn ... hopefully hitting the "apex" .. and accelerating out of the turn at optimal geometric angle as close to WOT (wide open throttle) as possible to begin preparing for whatever obstacle are on the road ahead.
When entering these turns, sometimes a down shift or braking is not enough to slow your vehicle for best control. If you brak first ... and shift second or vice versa .. your are spending more time than necessary adjusting your vehicle for optimal control and your are most likely not tackling the turn at the limits that your vehicle is capable of.
To minimize time and increase the chance of being able to use all of the great engineering of your vehicle to perform it's best .. you need to combine a brake, shift, rev-match execution ... aka .. heel-toe maneuver.
Hel-toe position is mostly self explanatory. There are three variations of "heel-toe" shifting that I have seen. The most taught is allowing you to feel the brake force applied with the toes of your throttle foot ... and moving your heel to the throttle while watching rpms, if necessary, to rev-match properly.
Variables including size of the vehicle space and of peoples legs and feet can greatly affect the ease of this maneuver.
It is for these aforementioned variable I have sen people "adjust" this maneuver two other ways.
2) Using your toes/ball of foot/brake side of throttle foot to press the brake and rolling/tilting your foot/ankle towards the throttle to engage to the throttle for a good feel for rev-match. (**I often use this technique in my mk3 supra. My feet are size ~11-11.5 .. and I find that the space by the pedals is not only limited by being close to the tranny tunnel ... but the brake pedal seems high and throttle pedal low .. and the spacing between them a bit odd .. making the maneuver a bit more difficult. Adding aftermarket pedals of certaing heights and widths .. and or adding spcaers to adjust the height of the pedals and or even bending the arms that support the pedals to your liking ... can all help you to customize your pedals for optimal heel-toe execution.**)
3) I once heard a man say that he puts his heel on the brake and tos on the throttle. This is not the method most used to teach the heel-toe maneuver. In my opinion, it may not often be taught like this because you only have "feel" to guage braking force ... and your toes probvide the most sensation ... while you have a tachometer to watch to ensure proper revs ... so the less feeling you get through your heel is not required as much.
Thats about it for the heel-toe shifting maneuver. Practice and I think you will find spirited driving more fun and more efficient.
SYST added:
Yeah, a guy there mentioned "double shuffling". Well same thing as double clutching, I think everyone should be doing this. Not only is rev matching always a great idea because it saves your clutch and doesn't make you bog. But double clutching also is much easier on your synchros so they will last long. I double clutch almost all of my downshifts. Oh and coming up to a red light and downshifting by slowly releasing the clutch is a bad idea, all you're doing is eating up your clutch. Everyone needs to learn how to rev match atleast. I can't give you any way of telling you when the rpm has reached a point where it's rev matched. You just keep practicing and you'll get it, I do it on instinct now.
Thats the nice thing about double clutching, you're rev matching at the same time. I can dump the clutch using this method when downshifting and have it be perfectly smooth. If you do it enough, you can just tell when you are able to just dump it, or when you gotta release the clutch a little easier. I would not drive any other way.
When i'm just normally driving, unless i'm not paying attention, you may never know I slip the clutch ever so slightly during an upshift. If i'm trying to accelerate I just drop the clutch and hit the gas once I am in the next gear. Anytime you slip the clutch you are eating away at it. Thats why I try to minimze it.
Between upshifts I try to get the clutch back on the flywheel before the engine drops to low in revs, that way I don't really even always slip it. Just practice, once you got it, you got it.
Having a manual transmission automobile allows you to match engine/CRANK rpm with drivetrain mph/rpm at will.
Engine rpm is obviously determined by the tach. Drivetrain speed determined by speedometer ... whether your rolling or not .. and if so .. then how fast.
Crank rpm controlled by right foot/throttle .... drivetrain speed engaged by left foot/clutch.
The closer you can match crank rpm with drivetrain rpm/speed .. the smoother/more efficient engagement becomes.
Pretty simple.
While vehicle is at rest ... drivetrain speed is ~0mph/rpm ... and engine idle is at about 650-750rpm (slow). This relationship is similar in all manual transmission vehicles .. and allows one move forward/backward (gear dependent of course) without increasing engine rpm/throttle any more than idle. Yes, if you slip the clutch slowly enough ...the car will move forward (1)... or backwards (R) .. if there isn't too mutch incline resistance from either direction ... allowing the torque to move the vehicle. If there is too much resistance .. slightly increase throttle/crank rpm to allow engine torque to overcome drivetrain resistance.
The engine only stalls if the engine bites too quickly to something that is stationary (significantly slower drivetrain). The better biting clutch one has ... or the less slip the clutch provides .. the easier it becomes to stall/slow down the engine too much.
Many clutches provide for slipping (partial biting/engagement to drivetrain before becoming fully engaged) ... allowing it to graze the drivetrain for engagement and allow some of the drivetrain and crank kinetic/potential energy to be absorbed by the other.
What this means is that if, at idle and no rolling speed (for best illustration), you slip the clutch out slowy enough to gradually engage the stationary drivetrain ... if the crank energy/power can gradually be transfered to the drivetrain ... the car will move more quickly the more the drivetrain is fully engaged by crank until 100% kinetic/potential energy is tranfered (minus loss to heat energy). Not to confuse mater anymore .. but engagement of clutch could be quicker if the car was rolling fast enough but no too fast ... just slow roll ... for crank rpm/drivetrain relationship.
Things get a bit more tricky while driving at increased speed ... but it is still the same concept. Name of the game is to get a feel of clutch bite/feel ... crank rpm ... and drivetrain speed .... and reckognize their relationships.
As long as no modifications are performed .. and motin resistance form extremem wind or inclines/declines is not affecting relationships too much .... the engine rpm in each gear will always produce the same relatoinal drivetrain speed.
This means that you should be able to determine what crank rpm in what gear will provide for smoothest engagement by observing drivetrain speed .. and you will now how to make the engagement with the clutch by getting familiar with it's particular function traits (bite hard .. slips alot ... firm/soft pedal .. etc).
If exact relation cannot be determined ... it is always better to exceed necessary engine rpm and have the clutch slip a bit or wheels spin in relation to vehicle travel direction .... rather than to have drivetrain speed exceed its relation to crank rpm ... and have the engine go into shock as it is thrown violently towards redline ... and causes vehicle speed to decrease for a split second or more ... significantly .. causing immense shock to clutch/drivetrain rigidity etc.
For instance .... 2nd gear on a r154/7mgte combination in near stock form allows around 5 through 60-65mph ... 3rd about 25-30 through 80-85mph .... 4th about 30-40 through 120-125mph ... 5th about 40-45 through top speed.
If cruising on road at about 55mph in 5th gear ... you suddenly want to pass a vehicle by accelerating as quickly as possible.
You want to be in the lowest gear that allows you to travel at your current speed .. but you also want some room to run.
55mph may be a tough decision for downshift selection in a near stock combo ... because this is very close to top of 2nd (which SHOULD provide for best pull ... ***but**) and there is pleanty of good run room for 3rd .. and it may provide the best power-band.
If you wanted 2nd .... you would have to rev to right about redline and drop/slip the clutch (depending on clutch traits) .. b/c this is the relation to crank rpm in that gear at that speed.
I would choose 3rd gear, most likely, due to better power curve (b/c let's not forget the **but** .. the stock ct26 chokes top rpm flow .. so the tip range rpm of a second gear pull would probably be a less desireable part of the power-band).
To shift into third .. at 55mph ... I would approximate engine rpm relation t be about 3000-3500rpm .. so for a safe bet I may rev to about 500rpm over my estimate and dump/slip the clutch to engage for best pull.
If during any gear engagement I chose not to match crank rpm with drivetarin speed ... and let of the gas and attempted to engage drivetrain and throttle at the same time ... or even worse throttle slightly after drivetrain engagement .. that's when violent drivetrain shock is felt. BAD for vehicle components .. bad for attempted performance.
Same relationship for all relevant crank rpm/gear/drivetrain speed ratios. Once you figure em out ... and respect the control you have.... I dont think you'll ever want to drive an automatice again .. unless it's for leisure or straightline performance.
_______
The "art" of heel-toe shifting:
You may have seen it on picture in picture instructional video or driving videos simply showing where the car is going and what the driver is doing with their feet...
Heel to is uesed for optimal control of the vehicle while combining braking, shifting (99.99% down-shifting), and rev-matching (which I have explained in detail above).
The most optimal time for a heel-toe shift is when wanting to corner your vehicle as fast as possible .... for grip driving.
Appropriate way to tackle a turn for grip driving is to slow adequately before you enter the start of the turn, power/accelerate with throttle through the turn ... hopefully hitting the "apex" .. and accelerating out of the turn at optimal geometric angle as close to WOT (wide open throttle) as possible to begin preparing for whatever obstacle are on the road ahead.
When entering these turns, sometimes a down shift or braking is not enough to slow your vehicle for best control. If you brak first ... and shift second or vice versa .. your are spending more time than necessary adjusting your vehicle for optimal control and your are most likely not tackling the turn at the limits that your vehicle is capable of.
To minimize time and increase the chance of being able to use all of the great engineering of your vehicle to perform it's best .. you need to combine a brake, shift, rev-match execution ... aka .. heel-toe maneuver.
Hel-toe position is mostly self explanatory. There are three variations of "heel-toe" shifting that I have seen. The most taught is allowing you to feel the brake force applied with the toes of your throttle foot ... and moving your heel to the throttle while watching rpms, if necessary, to rev-match properly.
Variables including size of the vehicle space and of peoples legs and feet can greatly affect the ease of this maneuver.
It is for these aforementioned variable I have sen people "adjust" this maneuver two other ways.
2) Using your toes/ball of foot/brake side of throttle foot to press the brake and rolling/tilting your foot/ankle towards the throttle to engage to the throttle for a good feel for rev-match. (**I often use this technique in my mk3 supra. My feet are size ~11-11.5 .. and I find that the space by the pedals is not only limited by being close to the tranny tunnel ... but the brake pedal seems high and throttle pedal low .. and the spacing between them a bit odd .. making the maneuver a bit more difficult. Adding aftermarket pedals of certaing heights and widths .. and or adding spcaers to adjust the height of the pedals and or even bending the arms that support the pedals to your liking ... can all help you to customize your pedals for optimal heel-toe execution.**)
3) I once heard a man say that he puts his heel on the brake and tos on the throttle. This is not the method most used to teach the heel-toe maneuver. In my opinion, it may not often be taught like this because you only have "feel" to guage braking force ... and your toes probvide the most sensation ... while you have a tachometer to watch to ensure proper revs ... so the less feeling you get through your heel is not required as much.
Thats about it for the heel-toe shifting maneuver. Practice and I think you will find spirited driving more fun and more efficient.
SYST added:
Yeah, a guy there mentioned "double shuffling". Well same thing as double clutching, I think everyone should be doing this. Not only is rev matching always a great idea because it saves your clutch and doesn't make you bog. But double clutching also is much easier on your synchros so they will last long. I double clutch almost all of my downshifts. Oh and coming up to a red light and downshifting by slowly releasing the clutch is a bad idea, all you're doing is eating up your clutch. Everyone needs to learn how to rev match atleast. I can't give you any way of telling you when the rpm has reached a point where it's rev matched. You just keep practicing and you'll get it, I do it on instinct now.
Thats the nice thing about double clutching, you're rev matching at the same time. I can dump the clutch using this method when downshifting and have it be perfectly smooth. If you do it enough, you can just tell when you are able to just dump it, or when you gotta release the clutch a little easier. I would not drive any other way.
When i'm just normally driving, unless i'm not paying attention, you may never know I slip the clutch ever so slightly during an upshift. If i'm trying to accelerate I just drop the clutch and hit the gas once I am in the next gear. Anytime you slip the clutch you are eating away at it. Thats why I try to minimze it.
Between upshifts I try to get the clutch back on the flywheel before the engine drops to low in revs, that way I don't really even always slip it. Just practice, once you got it, you got it.