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Originally Posted by Smoke Destructer
What exactly is that pedal trick supposed to do though?
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Basically, it changes the clutch ERGONOMICS (but not mechanical function) by altering the point in the clutch pedal stroke where the clutch disk contacts the flywheel, the point I call the "take-up point," and others variously call the "grab point," and "bite point," and so on. Some owners have found that the take-up point on their cars, where the clutch begins to engage, is comparatively high in the pedal stroke.
What does this mean?
First get a feel for the length of the clutch pedal stroke as you depress the pedal fully to the floor and then release it allowing it to come up fully to the top of the stroke. Get a sense of low LONG that stroke is. Now, depress the clutch pedal to the floor (engine running and car in 1st gear); then, slowly raise the clutch pedal to the point where the clutch
just begins to engage; note WHERE in the pedal stroke that engagement point seems to be. I like it adjusted to a point around 1/3 to 1/2 way up in the pedal stroke. This is what affects your muscle memory; how much do you raise your left foot (most of us use our left foot on the clutch
) before encountering the point in the stroke where the clutch begins to engage. I try to see to it that our cars all have the engagement point occur around the same point, with the same amount of foot travel; this makes it easier to transition from one car to another.
Adjusting this clutch pedal travel will also move the pedal "ride height," or where the pedal sits stationary in relation to the brake pedal. A lot of drivers like their clutch pedal to be level with their brake pedal.
If you adjust this, it is CRITICALLY IMPORTANT to make certain of the following two points: (1) Ensure that there is approximately ½" of free play at the top of the clutch pedal stroke. It's hard to feel in my BRZ. Get an idea of how it feels BEFORE messing with the adjustment. This free play is essential to ensuring that the clutch disk is FULLY ENGAGED at the
top of the stroke after you've taken your foot off the pedal. (2) Make certain that the clutch is FULLY DISENGAGED at the
bottom of the pedal stroke. If the clutch is still dragging on the flywheel and putting some drive through to the gearbox via the input shaft … this will wreak havoc with the synchromesh in your gearbox.
So, if you go too far with this pedal adjustment, your clutch life may suffer, or your gearbox life may suffer. Either way, you'll be unhappy paying for the repairs down the road.
When adjusted properly (see above), this pedal height adjustment does NOTHING to change the mechanical operation of the clutch itself. It does not change the throwout bearing, the pressure plate function, the clutch disk, or the flywheel function. The clutch disk seems to bite fairly quickly on this car, mine anyway, and perhaps this contributes to the awkwardness in executing smooth shifts. But, changing the clutch pedal ride height (and engagement point within the stroke) has NO EFFECT on the mechanical operation of the components when keeping it in spec. How
could it?
One might think that production variances would be small and that there would be no need to adjust this on a new car. I have not found this to be true on the new cars we have purchased over the decades. It's not unusual to find that I need to adjust our new car's clutch pedal ride height to get what I prefer. Just remember, if you do this, to keep it within spec: ½" free play at the top and fully disengaged at the bottom. There's usually some room to play with within those limits, and I can find an engagement point that falls where I prefer it and which closely matches my other cars while keeping it in spec.
Ergonomics are important. I dislike a clutch that engages high in the pedal stroke; I find it awkward to drive. Your mileage may vary, of course.
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Is it like the other "pedal dance" that puts the car into some sort of diagnostic mode?
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No, the "pedal dance" is entirely unrelated to what we're concerned with above. The pedal dance simply defeats some of the
electronic nannies for stability control, etc. It does not alter the nature of the function of the components, it just TURNS THEM OFF. It turns off EBD, which still leaves me scratching my head about the advisability of doing it. There does not appear to be a clear consensus of opinion about doing the pedal dance; some say it solves their problems, while others say it creates worse problems. This is largely competition oriented and would not apply to most street driving for most drivers. But, do read about it just so you're better informed and know what is possible, as the day may come when it may offer a possible solution to some difficulty you're experiencing.
I hope this has made sense to you and others, and has been helpful.
