double cluching

[tim hill]

i know that when you change down gears its better for the cluch if you match the speed of it to the rpm of the motor, but i'v heard people saying that double cluching when changing up is faster. is this bullshit? it kind of doesnt make sense to me

[GasGem]

no no no you have syncro's in ya box that do it all for you, if you double clutch you are just making the syncro's work twice, you figure will it be quicker and can you shift quicker while doubling the clutch... i don't think so,

before you ask, rev matching without the clutch fuk's your syncro's as they have to do all the work under full load.

flat shifting, leaving your gas pedal on the floor between gears toasts your clutch plate, and over rev's your engine.

Cheers
Eggy

[Badger]

sorry eggy, but matching the revs means your syncros don't have to do any work, and therefore live forever, whether you do it with the clutch or not (obviously nicer with clutch).
this will lead to faster changes as the syncros are what slows down the shift (hence the use of syncro-less dog boxes in competition)

when changing up you can change faster if you match the revs, but it is a bit harder to do as you need to reduce the revs to match. most mordern cars have a valve (or computer) which stops the revs falling to quickly after throttle snaps shut, an emission thing.

changing down is the biggy. you want to match revs, even if you are using the clutch, as if the road speed and engine speeds are out of sync when you lift the clutch pedal, and you are at the limits of adhesion, then the rear end will skid, and that could be enough to put you into a tree or the wall. of course on the street this is less important!

the other problem is when you are changing down, you are often braking too, this is when you do "heel and toe" braking. this is a complete mis-nomer, as you don't use your heel at all.

what you do is press the brake pedal with your big toe, whil e at the same time you are pressing the accel with your 2 littlest toes or the side of your foot. this takes a bit of getting used to, especially to not reduce braking while you lift off the accel!
You do this while the clutch is down and the box is in neutral during the change, and match the revs of the engine to what they will be once you have changed down.

just for info, double de-clutching is as follows:
foot on clutch
gear into neutral
foot off clutch
give some revs
foot on clutch
shift to new gear
foot off clutch

this is generally used with very large gearboxes (ie trucks) and is not quicker in a regular passenger car unless the gearbox is very stuffed.

I do not recommend flat shifting at any time

[GasGem]

Badger i agree totally,
i just couldn't pull off the long post, my point was rev matching without clutch toasts your syncro's as not every change will be perfect and apply some stress on your syncro's, but I myself often match with the clutch particulaly on down shift's and "hell toe" so to speak, all in all the point was all changes you need the clutch on a Gem box,

Cheers
Eggy