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Post by Mullet on Sept 24, 2003 2:15:32 GMT -5
On a down change i know blipping the throttle makes for a smoother change (if you get it right), but i find that if i'm driving hard (changing up) then a little blip on the throttle before i put it back in gear (i.e. halfway through changing up) makes for a smoother change too... Is this the best method to use or is there a better way (changing faster/leaving some power on - foot resting on the throttle)?
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PaulG
loves it here
Posts: 120
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Post by PaulG on Sept 24, 2003 2:55:32 GMT -5
Blipping on the down change is fine as you're setting the revs closer to the level which they need to be for the lower gear
eg.
change down from 4th to 3rd still maintaining 60mph revs will be higher in 3rd gear therefore blipping revs on downchange will aid gear change.
HOWEVER......blipping on the upchange has the opposite effect as the revs will be too high for the next gear and you'll end up slipping the clutch.
Double De-clutching.....
this is where you declutch - dis-engage gear - engage clutch fully (no gear selected) - dis-engage clutch - engage gear - engage clutch - voila!
Essentially it involves pressing the clutch pedal twice for one gear change and is something to do with setting the syncros in the gearbox at the correct speed. On some older cars you HAVE to double declutch but obviously it's not necessary on modern cars!
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Post by Mullet on Sept 24, 2003 3:07:17 GMT -5
Ok cheers Paul, i understand what you're saying about double-declutching but really don't see the point  |
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Post by Sale on Sept 25, 2003 4:26:28 GMT -5
If you still find time to feather/blip the throttle on the upshift, then you're shifting waaay to slow. The trick is to engage to higher gear at the same moment when the revs of the engine (while to clutch is depressed) "naturally" die down to the level that will be required by the higher gear. If you hold the clutch down for long (e.g. slow shifting) so that the engine revs fall down below the level needed by the higher gear, so that you need to blip the throttle, lifting the revs and getting the smoother change, then you're shifting slow. At some 6000 rpm, with fast shifting to, say 3rd or 4th, you shouldn't see the revs dropping by more than 700ish revs.
Double-declutching is an archaism long gone now (well, sort of gone ;D). Some 30 years ago the term was used to describe what we nowdays call a heel-and-toe. 30 years ago, cars (as well as trucks) didn't have synchros in the gearboxes, so you couldn't just depress the clutch once, and then disengage and engage the gear. One clutch press to disengage gear, then release the clutch (essentially car is then in neutral and the revs drop down), press the clutch again, engage gear and then blip the throttle to bring the revs up to the point where the gear change won't create a jerk. It was a much slower process and blipping the throttle was required by the gearbox itself, since it engaged gear more easily if the revs were matched, hence the need to even out the revs by throttle blip. This wasn't a "performance driving" technique, but a necessity then. Introducing of the syncromesh in the 'box eliminated the necessity for double declutching, but someone then thought of it as a neat archaism that could now be used to prevent the driven wheels lockup when braking and downshifting, by evening out the engine revs and road speed.
So esentially double declutching is kind of still used today, but in a shortened, renamed and abbridged form that had roots in the gearbox design gimmicks. Using double-declutching in today's cars is utterly pointless, heel-and-toe is sort of a double declutching technique of today.
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Post by Mullet on Sept 25, 2003 4:37:13 GMT -5
Ok, I'm only blipping the throttle for an up shift at low speeds (in traffic etc where you can't really keeps the revs 'naturally' high), so that the revs don't drop to like below 1000rpm.... It's not a problem (obviously) when 'racing'. I should really have said.
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