hotboyjamez

i know this is kinda a off-topic subject, sorry
i go to uga. and this kid in my history class. asked me about the fast and furious movie.
well do any of you remember when in The First Street Race, when the eclipse tappin out. and at the end of the race. Vin Diesel asked him something about " not granny double shifting " or clutching. like you should.
THIS QUESTION BEEN ON MY MIND FOR THE WHOLE DAY.. AND I CANT REMEMBER AHH.. anyways. if anyone knows. what does it mean? ahhh

scl23

Depress the clutch
Move the transmission to neutral
Release the clutch
Depress the clutch
Move the transmission to the next gear
Release the clutch
This give the gears in the transmission a chance to match speeds. It is not as necessary with today's synchromesh transmissions as it was with the non-synchro boxes I learned on or a racing "crash box" transmission w/o synchronizers.
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It's very difficult to master what's often called "double-clutch" shifting, or more properly called "heel-toe" shifting.

When downshifting a manual transmission without modern synchromesh systems (i.e., old cars or race cars with crashboxes) you can put excess wear on the gears, chipping teath off of gears.

Imagine being in fifth gear, with your RPMs around 3000. Fifth gear is now spinning pretty quickly, but the rest of the gears in your transmission are not spinning at all. If you were to downshift to fourth (without "double-clutching") fourth would go from dead-stop to spinning furiously in a mere thousandth of a second. Your transmission, needless to say, wouldn't like that. To compensate, you could: 1) disengage fifth (i.e., shift to neutral), then blip the throttle. This would (more gently) spin all the gears in your transmission. Then 2) engage fourth.

If done properly, you have matched the gear speed with the speed of your engine. Instead of instantly puting a gear under load from 0 RPMs to several thousand, you have increased the RPMs without added stress loading.

Now the reason it's called "heel-toe" shifting is because under race conditions the driver is applying the brake with his heel, and then blipping the throttle with his toes.

1) push clutch pedal in and shift to neutral
2) release clutch and blip the throttle
3) push clutch in and shift to lower gear
4) release clutch to engage the selected gear

All steps are completed WHILE braking with your right heel. This requires some FANCY footwork. If you watch NASCAR when they race on road-coarses (i.e., Watkins Glen and Sears Point) they usually have a footwell camera mounted in the cars of the more talented road-coarse drivers (i.e., Mark Martin, Ricky Rudd, Rusty Wallace, Jeff Gordon). It literally looks like they're dancing on the pedals. Pretty Cool to watch!

If done properly it's as seemless as the new-technology CV transmissions. I've been told by a friend who races professionally that it can mean a BIG difference in wear and tear as well.

Zapata

shouldn't you still double clutch even with the synchro gears?

scl23

You're asking a guy who drives auto w/ manumatic (aka tiptronic, or whatever nifty name that's in vogue right now.) I love to drive my roommate's BMW 325i 5 speed when I feel the need for stick but after my 2nd stall in 5 minutes, he kicked me out of it...

yayaya143

haha ya, i remember first time i ever touched a stick was when i was like 12 at an arcade. On one of those racing games, i sat down, not realizing its a stick with a clutch. light turns green, step on gas, car wont go, i was like wtf, then my cousin is like its a stick, use the clutch, i was like what clutch, hes liek the thing on the left, i steped on it, henry, it still wont go, looked up, him and everyone there was cracking their ass up laughing at me. Till this day i still dont know how to drive a stick. hehe

vteclude

Do you drive a CLS? I go to Georgia also and have seen a few CLS around? Do you live in Athens?

cakennedy

Two different things. Heel-and-toe works naturally with double clutching, but can also be done without releasing the clutch between gears, to match engine and gearbox revs. Double-clutching ("double-declutching", actually) is not necessary or useful on cars with synchros, but heel-and-toe rev matching certainly is. The only time I spun my car at the track last weekend was on missing a throttle blip while downshifting and braking for a very tight turn. Engine was going much slower than gearbox, whic locked the rear whels just long enough for the back end to come all the way around.

cakennedy

PS - you forgot one VERY important step:

scalbert

Having not seen the movie I can't fully get involved. But it is my understanding that the races mentioned were simple drags. This would mean that you were always under acceleration and only upshifting negating the need for heel-toe, etc.

Now I could see how shifting without lifting would be relevant... Or maybe they were running turns where downshifting was required??

yayaya143

nope itwas during a straight race

scalbert

So then I would assume that the movie was just throwing out terms knowing most people would not catch the mistake.

M5 Lite

Movie was very weird on some parts. The part that really gets me is this:

Supra vs. the Ferrari part where the Ferrari keeps up from the light and all the way up (looks like they hit a 100 by now). Yet then, he races a 10 second car at the end of the movie and keeps up!!

Does this mean that the 'stock looking' Ferrari was running 10s?

monkeymato

Heres a nice explaination with pictures

http://www.turnfast.com/tech_driving..._heeltoe.lasso

moomaster_99

This thread is stupid.....when they were referring to double-clutching ...this is a technique used to make the motor rev faster....after gaining some traction...you go WOT..and then blip the clutch for an instant at low revs....and it jumps, thus, revving the car faster....all that heel-toe shit is for track racing....and match revving is not the same thing either.

cakennedy

My nomination for Clueless Post of the Day

A technique like that would slow the car dramatically. I can't realistically believe that anyone would employ that, and call it double-clutching...? Also, I've never heard the phrase "all that heel-toe shit" either

hotboyjamez

than your ass must be a newbie, cause there are such thing called that. so i nominate u. to stfu for a day, thanks