Shifting Techniques
Manual Transmission
"Heal and toe" refers to the right foot position as it operates both the gas and the brake pedal at the same time. Actually, on most modern cars it's better to use the ball of the foot (under the big toe) on the brake pedal and the edge of the foot (about halfway between the little toe and the heel) on the gas pedal. I think it's better to refer to it as "ball and edge".
There are some individual variations in position based on foot size, type of shoe, seating position, pedal placement, and so on.
It's important to give preference to the brake pedal for safety reasons, and because the brakes require more accurate control feel than the engine speed.
I have size 11 shoes. In my ti I position my foot so that my heel is on the floor near the base of the gas pedal. The ball of my foot is centered half way top to bottom on the brake pedal, with the edge of the brake pedal at my middle toe. My foot is in approximately the eleven o'clock position when I am doing this. In this position I can firmly apply the brakes, and the control feel is pretty much the same as if I was operating the brake pedal alone. By rocking my foot, I can apply the gas without varying the pressure on the brake pedal (this is one part in particular that takes practice). When I'm done braking, I slide my foot over so that it's directly on the gas pedal. My heel has remained on the same place on the floor.
Some people, particularly with smaller feet, don't keep their heel on the floor. There are some other cars that I lift my own heel from the floor. I like to have it on the floor if possible because it makes it easier to consistently control the brake pressure while rocking the foot. It's important not to have the seat too far back because the knee needs to move side to side just a little bit when doing this. Having the leg stretched out too far restricts this motion.
Aftermarket pedal covers can benefit some cars and foot sizes by bringing the edges of the pedals closer together and by changing the height relationship between the pedals. On some cars with hanging gas pedals, the gas pedal can be bent to a more favorable position (this can't be done on the ti because the pedal is hinged from the floor). I don't recommend trying to bend the brake pedal. Also be aware that pedal covers can reduce the space for a larger foot to fit between the brake pedal and the center console.
I have found the stock pedal positions to be quite good for me. Obviously this is a highly individual thing. I would suggest that people spend a significant amount of time experimenting with foot positioning before trying to reposition the pedals or investing in pedal covers.
Why heel and toe (ball and edge)?
One basic situation is starting up hill. Ball and edge allows a smooth transition from brake to gas while operating the clutch with the left foot so that the car doesn't move backwards.
Many people also use the term "heel and toe" to refer to rev-matching while shifting and/or double clutching, but it's actually just one component of these processes.
Rev-matching refers to matching the engine speed to the transmission input speed before re-engaging the clutch. This is particularly desirable when downshifting for a corner. In a hard corner, the suspension needs to be stable and the tires need to be loaded so that all of their traction is being used to generate cornering force. If the engine is at a different speed than the transmission input when the clutch is re-engaged, this will generate a force on the driveline that will upset the stability of the suspension and will cause the tires to exceed their traction capability if the corner is being taken near the limit.
It *is* necessary to rev-match if a corner is to be taken near the limit. It isn't necessary for slower corners, but it will make them smoother.
Double clutching is a technique for rev-matching the transmission's *intermediate shaft* to the output gear that is to be selected. This is a function that is normally handled automatically by the transmission's synchro-mesh gears (or synchro's). It is useful to double clutch for extreme gear changes, for older transmissions with worn synchro's, or simply to save wear on the synchro's. It's also an entertaining thing to do.
Before I get into the specifics of rev-matching and double clutching, it would probably be good to review the inner workings of the clutch and transmission.
The ti's gasoline engine has a limited output bandwidth of approximately 1000 to 6000 RPM. It can't operate from 0 RPM (like an electric motor can), so it needs a device (the clutch) to disconnect it from the drive train so that it can idle while the car is at a standstill. The power is not constant from 1000 to 6000 RPM, so it is also necessary to have different gear ratios in the transmission to extend the car's useful operation speed range and to maximize available acceleration. The clutch also serves to disconnect power to the transmission when changing gears.
THE CLUTCH:
The clutch is integrated with the engine's flywheel. There is a disk with friction material, similar to a brake pad, that is connected to the transmission input shaft on a sliding spline. This disk is surrounded by the flywheel surface on one side, and the pressure plate surface on the other side. The pressure plate is spring loaded to squeeze the clutch disk against the flywheel, effectively making a solid connection. The pressure plate can be moved by pressing down on the clutch pedal. This releases the coupling pressure between the flywheel and the clutch disk so that they can rotate independently.
There are three states the clutch can be in:
CLUTCH DISENGAGED (pedal pressed down): The engine flywheel and the clutch disk can rotate independently. No power is being transferred.
CLUTCH SLIPPING (pedal brought up just to the point that the clutch starts to grab): The engine flywheel and the clutch disk are still rotating at different speeds, but power is being transferred. If the clutch pedal is continued to be brought up properly, the speed of the engine and the clutch disk will be brought together. This is the state that clutch wear occurs.
CLUTCH ENGAGED (pedal up): The engine flywheel and the clutch disk are locked together. Full power is being transferred, and no clutch wear is occurring.
THE TRANSMISSION:
The transmission has an input and an output. The ti has five forward gear ratios (fifth gear is a straight 1:1, not an overdrive) and one reverse gear ratio. The forward gears are all *constant-mesh*, that means that the gear teeth for all ratios are always engaged with each other at all times. Instead of sliding a gear out of engagement with another gear, the gear is disengaged by disconnecting it from the *shaft* that it is on. Only one gear ratio pair can be connected to the shaft at one time. The reverse gear is an actual sliding gear whose teeth actually slide out of engagement when it's not being used.
Each forward gear can be coupled to its shaft by a sliding locking coupler. This coupler connects splines on the shaft to splines on the gear. The coupler needs to be at the same speed as the gear splines to avoid grinding. (When people refer to "grinding the gears", it is actually the splines that are grinding, not the gear teeth). To synchronize the coupler with the gear splines, there is an intermediate device called a synchro-mesh.
The synchro-mesh is a lightweight ring with spline teeth on one side, and a conical friction surface on the other side. It is positioned between the sliding coupler and the gear splines. The gear also has a conical friction surface that mates with the surface of the synchro-mesh.
When a gear is to be engaged, the shift linkage selects a sliding coupler to connect to a gear. At this point, the coupler and the gear to be engaged are usually spinning at different speeds. As the coupler starts to slide, it first engages the spline teeth of the synchro-mesh ring. Because the synchro-mesh is so lightweight, it can virtually instantly change speed to match the sliding coupler that was just forced into engagement with it. It then becomes part of the coupler. As the coupler continues to slide towards the gear splines, the friction surface of the synchro-mesh ring is pressed into contact with the friction surface of the gear assembly. This friction causes the transmission's input shaft (which at this point is hopefully disconnected from the engine by the clutch) to be accelerated (or decelerated) so that the coupler and the gear are spinning at the same speed when their spline teeth finally engage.
I think it's helpful to find some junk transmission parts to move around by hand to help visualize this process.
A synchro-mesh is limited in how much mass it can accelerate and how fast it can do it.
DOUBLE CLUTCHING:
There are *three* separate spinning entities that need to be coordinated when shifting: The engine. The transmission input. (I'm going to refer to this as the intermediate shaft). The transmission output (which is directly related to the vehicle speed).
When the clutch is disengaged (pedal pushed down) and the transmission is in neutral (such as when shifting between two gears), the intermediate shaft is essentially free spinning. In normal shifting, we rely on the synchro's to control the speed of the intermediate shaft as it engages with the gears connecting it to the transmission output.
Decades ago, transmissions didn't have synchro-mesh. (Many large trucks still don't). On these transmissions, it is necessary for the driver to manually control the speed of the intermediate shaft so that it matches the speed of the gear to be engaged. This is done by the following process when shifting from one gear to the next:
1) Power is removed and clutch is disengaged (pedal down). 2) Transmission is shifted from original gear to neutral. 3) Clutch is re-engaged (pedal up). (Driver now has control of intermediate shaft speed by controlling engine speed). 4) Driver 'blips' throttle to match intermediate shaft speed to speed of new gear. (This takes practice to get the right match). 5) Clutch is disengaged (pedal down). 6) Transmission is shifted from neutral into new gear. 7) Clutch is re-engaged (pedal up) and power is applied.
Steps 1 - 3 can be done casually or quickly. Steps 4 - 6 *must* be done quickly so that the intermediate shaft doesn't slow down again before it's engaged. If step seven is also done quickly, the engine will also be 'rev-matched' to the rest of the driveline so that engagement will be smoother.
REV-MATCHING:
When taking off from a stop and then going up through the gears, steps 1,2,6,7 above are the normal shifting method for each gear change. The synchro-mesh are more than enough to control the intermediate shaft speed. The engine will passively rev-match itself because it slows down naturally and this is appropriate when shifting up.
When down shifting, the engine needs to spin faster as it engages the new gear. This can be achieved by 'blipping' the throttle as the transmission passes through neutral. If the engine isn't manually sped up by the driver, it will be sped up by the driveline when the clutch is re-engaged. This can be OK for normal street driving, but if the car is cornering near the limit this can upset the suspension and the tire adhesion.
The synchromesh are usually adequate intermediate shaft control when down shifting one or two gears. Aggressive downshifts (like a 5 - 2 shift from high speed) can benefit by using double-clutch shifting to assist the synchro's. Shifting into first gear in a hard corner is nearly impossible without double-clutching (this is useful for those really tight hairpins, especially if they exit uphill).
LEARNING TO DOUBLE CLUTCH, REV-MATCH, ETC...
I think that the biggest problem people have learning these techniques is that they try to incorporate everything all at once. The following are suggestions that I have for progressively learning things one at a time.
GETTING INTO GEAR AT A STOP:
Because the synchro-mesh doesn't operate unless something is turning, it's easiest to get into first gear by shifting from neutral into first just before the car comes to a complete stop. If the car is already stopped, a lot of extra force may sometimes be required if the spline teeth don't match up. (Sometimes it might help to briefly re-engage the clutch to spin things around again). If the car is moving too fast, a lot of effort is required to get the lever into first (it might even 'crunch' if the synchro's capabilities are exceeded).
Try this exercise: When slowing to a stop, push in the clutch and *lightly* press the shift lever from neutral towards the first gear slot at around 10 MPH. Don't force it in. As the car slows down, there will be a point that the lever easily slips into gear by itself. This will occur just before the car comes to a stop.
What is happening here? The intermediate shaft quickly slows down (due to friction) to near zero speed. This results in a fairly large speed difference between the intermediate shaft and first gear. The first gear synchro *resists* the lever movement. As the car slows down first gear also slows down. When the car is almost to a stop, first gear has slowed down to the point that it nearly matches the intermediate shaft's speed. At this point, the synchro is able to accelerate the intermediate shaft to a matching speed. When the speeds match, the force required to engage the splines is reduced, and the lever slips into place.
This is a rather slow, passive rev-matching situation. Using this technique results in a smooth, low-effort engagement into first gear when coming to a stop at a light. It reduces the wear on the first gear synchro.
More importantly, this is a good way to learn to recognize the 'feel' of a properly actuated synchro. This light - touch engagement is something to strive for when learning to actively match revs with the engine and double clutching. Some people refer to this as treating the shift knob like an eggshell. By *accurately* shifting, shifts can actually be done faster than by forcing the shift lever with muscle. Again, it also has the benefit of reducing transmission and clutch wear.
SIDE NOTE ON GETTING INTO REVERSE:
Because reverse is done with an actual moving gear (and no synchro's), the car and the intermediate shaft must both be stopped for the gear teeth to match up. This is most commonly a problem if a person wants to go into reverse after the car has been idling in neutral. If one just pushes down the clutch pedal and shifts into reverse, it will grind.
One approach is to simply wait a couple of seconds after pushing down the clutch pedal so that the intermediate shaft can come to a halt before shifting into reverse. To do it faster, you can push down the clutch, shift briefly into one of the forward gears (using its synchro to slow down the intermediate shaft) and then shift instantly into reverse.
To instantly get into reverse after braking in a hard stop (such as when driving a gymkhana course), leave the transmission in the forward gear you were in. At the moment you get to zero speed, the lever can be thrown into reverse (because the intermediate shaft was halted when it was engaged to the last gear), and power can then be immediately applied.
SHIFTING UP WHILE ACCELERATING:
When shifting up from one gear to a higher gear both the engine and the intermediate shaft will naturally slow down. This will passively bring them near the speed of the higher gear. Because of this, active rev-matching or double-clutching are rarely required.
Another exercise: When upshifting, try to use the same 'egg-shell' pressure on the shift lever to slip it into the next gear. When the clutch pedal is pushed and the shift lever moves through neutral, the intermediate shaft drops in speed and will quickly match the speed of the higher gear. This is the point that it will almost *seem* to pull itself into gear. The engine takes slightly longer to slow down because it has more inertia. This usually works out well because it is a moment after the gear is engaged that the clutch needs to be re-engaged. If the clutch is re-engaged and the power smoothly reapplied at just the right time, there won't be any 'shock' in the drivetrain.
It's a little hard to describe in words, but with practice it's possible to integrate this entire upshift sequence into what seems like a single fluid motion that takes only a fraction of a second.
There are three indicators to determine how good a shift is: Was only light pressure required on the lever? Was the shift smooth? Was the shift fast?
To be complete, I should mention that there is one exception for forcing the shift lever. To get the very last little bit of acceleration out of a car, it can help to rush the shift sequence by forcing the shift lever into the next gear and re-engage the clutch with the engine already on-power. This can *slightly* reduce shift time and throw some extra inertia from the engine into the drive train. This technique definitely adds wear to the synchro's, the clutch and the rest of the drive train. If the car isn't being pushed to the point of lighting up the tires (which also accelerates wear), this technique isn't worthwhile.
Generally speaking, a really well executed light-touch shift can be done quicker than most people can power-shift. It certainly is friendlier to the car. The car will also handle better if it's accelerating on a twisty road. I usually only power-shift if I'm drag racing.
DOWNSHIFTING:
There are three basic scenarios involving downshifting that I can think of:
Downshifting (without braking) from an established original speed (such as when passing another car).
Downshifting while braking, and then re-accelerating in a straight line (no corner, such as when braking for a car that is turning up ahead).
Downshifting while braking to enter a corner.
(OK, I suppose there might also be occasion to downshift to enter a corner without braking, like when turning off a road with a low speed limit).
I listed these three scenarios in what I considered to be their order of difficulty.
Most people when they're learning to drive a manual transmission, learn to deal with downshifting for a corner first. They do it without active rev-matching or double-clutching (which, of course, is fine). By approaching and going through the corner at a casual rate, there isn't a big speed difference in the engine, intermediate shaft, or the rest of the driveline. The synchro's can handle the engagement, and it's possible to smoothly engage the clutch while *exiting* the corner. With additional practice it's possible to use this type of technique to get through corners reasonably quickly.
What's necessary to get through a corner as quickly as possible?
The tires basically have a fixed amount of traction on any given road surface. This traction can be used for braking, cornering, accelerating, or a combination of braking-cornering or accelerating-cornering. If the car is cornering near the limit, there is no traction available for braking or accelerating.
The suspension needs to stay stable and the steering needs to be a smooth as possible.
In simple terms, a good corner consists of braking in a straight line, smoothly transitioning into the corner, holding the corner for its tightest section, transitioning out of the corner onto the gas, and accelerating out of the corner's exit.
The two transitions are the most important parts here. The idea is to have the tires near their maximum traction while braking, and then to smoothly change the *direction* of the traction to sideways for the corner. It's the same thing when exiting the corner. The direction of the traction is changed so that car accelerates.
I want to re-emphasize that the goal is to hold the *level* of the tires' traction CONSTANT, while CHANGING only the *direction* of that traction.
If there is a gap between releasing the brakes and steering into a corner, two things occur. The suspension becomes unsettled (so it can't corner as well), and time that the tires could have been working is lost. Again, it's the same thing when getting out of the corner to accelerate.
How does shifting affect all of this? If there is any jerking of the driveline when cornering near the limit, this will cause the limit to be exceeded because of the additional load imposed, even though momentary, on the tires. The driver has to be concerned with interpreting the corner and the situation, and monitoring how the car is responding, all while trying to operate a steering wheel, shift lever and three pedals with two hands and two feet.
Most 'performance' corners require a reduction in speed. This implies that a downshift of one or more gears be made so that the car is in the correct gear to accelerate out of it. A five - two downshift is a big change.
When driving a fast corner, the downshift can't be done before braking because the car's initial speed would cause the engine to over-rev.
On a rear wheel drive car, power needs to be lightly applied to the wheels during the corner so that the suspension is neutral or oversteering slightly (this is touching on another subject). This means that the downshift needs to be done before entering the corner.
This leaves one place to downshift: towards the end of the braking phase of the corner.
The shift has to be done while braking, and the engine needs to be sped up so that it will rev-match the new gear so that the tires won't be jerked past their limit. All three pedals need to be operated at once. This is where heel and toe (ball and edge) operation of the brake and the gas is required. Depending on how many gears down the shift is, the abilities of the transmission's synchro's, and the general pre-disposition of the driver, double-clutching may also be called for to get the shift lever into gear.
BACK TO LEARNING THE TECHNIQUES:
Recall the three downshifting scenarios I described above. Many people that I've observed trying to learn to rev-match and double-clutch (including myself) will try to learn it while cornering. This is the most difficult downshift. It's much easier to practice without braking or cornering. The braking can be added second, and then finally the cornering.
Please remember to stay safe. Try to keep away from traffic when trying something new.
EXERCISE:
On a straight section of road, establish a steady speed in fifth gear (perhaps 50MPH). Without breaking (use your right foot on the gas pedal only), downshift into forth. Try to blip the gas as the shift lever passes through neutral so that the car doesn't doesn't pull backwards or forwards when the clutch is re-engaged. Don't try to accelerate once you're in forth. Just continue to maintain a steady speed. Shift back up into fifth. Again, try not to jerk the car. Repeat this sequence going back and forth from fifth to forth. If you've got everything right and smooth, the car will just go steady down the road as if you weren't shifting. The only thing different is the sound of the engine changing speeds. At least at first, don't worry about making the shift fast.
Next, try the same thing going back and forth between fifth and third. This will require a little more gas when blipping the throttle. Focus on keeping the car's forward motion rock-steady.
Once you've got that down, try different sequences of third, forth and fifth.
At this point, you might want to throw in double-clutching while downshifting. As the shift lever passes through neutral, momentarily let up the clutch pedal at the same time the throttle is being blipped. If it's done correctly, the shift lever should slip into place much easier than without double-clutching, especially when going from fifth to third.
Try a similar exercise at 40MPH using second, third and forth. When you can downshift into second (this usually requires double clutching) at 40MPH and not affect the car's motion, you've got a good handle on this exercise.
The last part of this exercise is to accelerate at the end of a downshift. The idea is to be going at a steady speed, downshift by two gears, and take off. Try to integrate this into a single fluid motion. The acceleration should just appear as a big push from behind, without any jerking. Slow back down to a steady speed and repeat.
It is a rare automatic transmission that can downshift from speed as good as a well done downshift with a manual.
If you are new to this, I wouldn't proceed past this exercise for at least several days of practice, and probably weeks.
EXERCISE WITH BRAKING:
With the car off, try to find a seating and foot position that allows you to operate the brake and the gas pedal with your right foot at the same time using the ball and edge position I described. While pushing on the brake pedal, try to learn to blip the gas pedal without varying the pressure on the brake.
This inevitably will feel *very unnatural* at first.
In the course of your normal driving, practice blipping the gas pedal while you brake (don't try to downshift). Trying doing it during light braking and heavy braking. Try to bring the engine up to different speeds. The idea is just to get used to blipping the throttle while braking, without worrying about accomplishing anything with the engine. The goal is to not let the operation of the gas pedal affect the braking.
When you think you're ready, try braking and blipping the gas to rev-match into a downshift.
The next step requires an open stretch of straight road without traffic.
Basically just brake from speed, to a rev-match downshift at the *end* of the braking. Accelerate back up and repeat. Try it with and without double-clutching. Try it with light braking and heavy braking.
All the usual goals apply: Smooth transitions. Light touch on the shift lever. Unified fluid shift motions.
Stop and go traffic is an excellent opportunity to practice this exercise. I know people that dislike driving a manual transmission during rush-hour. Personally, I prefer a manual because it gives me something interesting to do with my driving in an otherwise tedious situation.
CORNER ENTRY EXERCISE:
Suspension loading might best be practiced first without downshifting. The exercise is only about getting into a corner. Just push in the clutch while braking and don't worry about the gas. Wait until the corner is completed before trying to downshift or speeding up again.
Brake as you approach a corner. Try to be conscious of the level of braking force that you feel. When you reach the point where you start to turn the steering wheel, lift off of the brake in unison with moving the steering wheel.
The goal is to feel the force swing sideways without varying in intensity. You shouldn't feel any gaps in the 'tug'. There also shouldn't be any pulses in the force. Keep it smooth and uniform.
Try varying how fast you turn in. The faster you turn in, the faster you need to get off the brakes. Doing corners with slow turn-in is good for practice because it emphasizes the steering/braking coordination more.
FINALLY, THE WHOLE DEAL:
If you've gotten through all of the exercises up to this point, adding the final steps should be a relatively easy process.
Brake timing doesn't have to be an issue at first if you practice at reduced speeds with moderate deceleration. The main thing to focus on is to get the downshift timed so that it is *completed* just before you start to turn the steering wheel. As the clutch is re-engaged, the gas should be held at the level where it will be during maximum cornering force.
Transition the braking into steering as in the previous exercise. When it's time to straighten out, transition into the gas in a similar manner. Just swing the direction of the force around without any gaps or surges.
Here's the entire step by step process for a 90degree corner from a 55MPH road to another 55MPH road:
1) Begin braking. 2) Clutch pedal down, transmission lever in neutral. 3) Clutch up, blip throttle. 4) Clutch down, lever into second. 5) Clutch up, lightly apply the gas just enough to load the drivetrain. 6) Transition off of the brakes into the steering. 7) Hold the corner (maintain the gas just below where the back end would start to slip out. 8) Transition out of the steering into full gas. 9) Shift up when needed.
FINAL NOTE:
The whole process of learning to shift well takes lots of practice and determination, but it's well worth the effort. Everyone that I know who's learned to do this really ENJOYS shifting. I believe all of them have a really strong preference for manual transmissions. I know that I do.
I hope that all of this makes sense and that some of you will benefit from both the explanations and the exercises.
Regards,
Brian Brown. BMWCCA #130878 '96 318tiS
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