This is probably a stupid question, but it's bugged me for years. I ride performance motorcycles, teach road-racing and smooth shifting is important. I feel I'm pretty good at it. Everything on a motorcycle is about being smooth and precise. I imagine cars are the same way. Smooth, deliberate motions all the time. But a motorcycle transmission needs to be snicked into gear super-quickly with quick taps. I've been driving manual transmissions in auto's for nearly 20 years and when I drive sedately I'm as smooth as an automagic slush-box transmission. But when it comes time to drive quickly/assertively at higher revs, my car shifting blows. Not as smooth as I'd like it to be. lurchy/jerky; and that can't be good. Shifting down I feel like I'm abusing the poor clutch, using the clutch to ease into the proper gear for the next corner like I would on a motorcycle, but it doesn't feel right in the car. Shifting up I get an ugly pause/hesitation between gears. If I go back to the throttle early its ugly, if I wait until the clutch is all the way engaged, its just as bad. What are some techniques to smooth out shifting, up and down when driving "spiritedly"? Thanks, dp
Upshifting, even quickly has always felt pretty natural to me, it's probably not as quick as a motorcycles shifts but I'm not hammering on the shifter either. Downshifting is only done smoothly once I've mastered the exact amount of throttle blip to give her for a certain condition. I nearly always rev match on downshifting anymore.
Is that the "heel/toe" shifting I keep hearing about? Toe on the brake? heel on the throttle to match revs? dp
Sorta, I have wide feet so when I'm driving spiritedly it's more like leftside/right side of foot. When driving normally though and just slowing down or making a turn on the roll I still give it a little blip to avoid having to drag the clutch to make it smooth.
Like this? [ame="http://www.youtube.com/watch?v=klMur6TPkrM"]YouTube - Race Car Driver & His Footwork[/ame]
Something like that. Keep in mind those are not stock pedals and were probably adjusted for that particular individual. A heel/toe is a very confusing term and tends to steepen the learning curve for a lot of people. For most people it ends up being big toe side of the foot on the brake and little toe side of the foot on the gas. You rotate your foot to blip the throttle as you apply the brake.
i have noticed that the mini's stock pedals tho small are set up perfectly for "heel toe" but more accurately its left side of foot on the brake right side blipping the throatle in the mini this may not apply to any other vehicle but certainly to the mini
Helps to heel and toe whenever you are driving, that way it's more fluid and second nature when you really need it. Also let's you feel just how much of a blip is needed.... A blip doesn't mean banging it against the rev limiter...:crazy:
Also the upshifting shown in the video is on a sequential gearbox and not a street driven "H" pattern box. Up shifts need to be slower and more fluid. A light grip on the shifter is all that is needed, many times only two fingers or an open palm. If you yank the shifter too fast and hard you do not allow the engine rpms to drop and the synchros time to do their job and cause jerkyness and accelerated wear. Rev-matching and heel-toe shifting are two different but similar techniques used for down shifting. Rev-matching is used when you are not trying to operate three pedals with two feet, ie slowing down by lifting off the accelerator and down shifting. During rev-matching as you slide the shifter through neutral you will blip the accelerator as you slide into the next lower gear and let out the clutch. Heel-toe is a little more difficult as you operate three pedals with two feet. There are many web sites dedicated to heel-toe and rather than reinvent the wheel I'll let you search them out. As minimark said, practice makes perfect. Enjoy, have fun, motor on.
Well, I did a run over our local East Canyon yesterday - really technical, steep road with lots up and down-hill corners. The heel-toe thing started to make more sense as I did a few of them correctly and you could really feel how much smoother it was. Still need practice so I can be as smooth with the brake as I like. (too easy to blip/rev-match and still affect the brake pedal). I did notice, that it seemed to work a lot smoother when I really rotated my foot a lot. Also, this is stupid, but I was a lot smoother when I kept a mental tab on what gear I was in all the time - that way I didn't, or was less apt to, shift into the wrong gear. I assume this will go away as I become more familiar with the car. Downside of all this? When I came back the entire car was covered in a light dusting of brake dust. Stupid BMW brake pads.... dp
A visual representation of "heel-toe." Arrow are applied force, X is no touch, and O is held. This is such second nature for me, I operate the brake in any car with only half my foot. In most cars, the brake and gas are far enough apart that you can have enough braking force before your foot reaches the gas. If you watch closely, that transmission is an H pattern, but it probably has a dog engagement. The driver certainly knows his way around Tsukuba Circuit.
In older transmissions and some racing trannies, they don't have synchros like a modern street tranny and the blip is to assist in engaging the gear properly.. The benefit in using it to lower lap times is not to effect weight transfer, to many rpm's and the car accelerates transfering weight to the rear, on turn in not desirable, and to little rpm, weight is tranfered to the front and the driven wheels will have less traction (more braking).... All things that destabilize weight transfer and your control over it with the brake and throttle. Heel and toe is an art that needs lots of practice to perfect (I haven't yet but getting there) and when done well is totally subconsious.. A student's 2cents.