I have been driving my new vette for a week now ( http://forums.corvetteforum.com/zerothread?id=361566 ), and this being my first manual transmission car (gimme a break, I'm only 19!), I have a couple questions.

First, in the manual it says don't skip more than one gear when shifting down (ie: don't go from 6th to 3rd, but 6th to 4th is okay). Is the reasoning behind this (1) it is much easier to over rev and hurt the engine, or (2) the syncros will have to work like freaks to get the layshaft up to the speed of the lower gear you're shifting to, thus putting wear and tear on them. Problem 2 could be solved by double clutching (I think?, more on that in a second), and problem 1 could be avoided by knowing what rpm your engine can rev to in a specific gear (ex: shifting from 6th to 3rd at 75mph won't redline the engine, so that is fine; but shifting from 4th to 1st @ 60mph would murder your engine, so don't do that). Any other reasons NOT to skip more than 1 gear, and if not, is it okay to skip more than 1 gear if the guidelines I mentioned are followed?

Second, I have a friend who drives a stick, and has been for a while, and he told me to double clutch on an upshift. I was mostly confused by this, as it contridicted the way I understood double clutching. I'll explain the why's of double clutching, as I see them, and someone correct me if I'm off.

Okay, you are riding along in 3rd and want to shift to 2nd. You push in the clutch, and slam the shifter into 2nd. The layshaft and engine speed in 3rd gear do not come close to matching your road speed in 2nd gear, so the syncros do their magic, and you make it into second, albeit with a nice jolt. Now you could double clutch this and make the transition smoother. Clutch in, shift to neutral, clutch out. The engine and layshaft are equal, but are still too slow to match the speed you are moving at when you shift to 2nd, so your blip the throttle to get the revs close to where they will be in second, push in clutch, and shift to second. Assuming you were close, the syncros don't have to do much (if anything), and there is no jolt because of engine/layshaft and speed in 2nd are already equal. This provides less/no wear on the syncros, and no annoying jolt. Is this all accurate?

Here is where my confusion sets in. You're traveling in 1st at 3000rmps, and want to shift to second. Push in the clutch and let off throttle and shift to neutral, the engine and layshaft will both slow down due to friction, and eventually get to the 2nd gear speeds, and then you drop it into second and let out clutch. No jolt, no syncro work, no double clutch. Double clutching here would seem redundant, because the engine and layshaft naturally fall the the correct speeds, unlike in a downshift where they must work against friction, thus the throttle blip. Is this correct?

My friend said to double clutch especially in drag racing. I figure he has seen the Fast and the Furious a few too many times. Double clutching in a drag race would slow you down, right?

Thanks for the help!



[Modified by graddium, 2:38 PM 8/10/2002]

 

There is no need for double cluthing as you said but it does make the shift smoother which I personally like. I am assuming they recommend not downshifting too many gears to aviod actavating the rev limiter.

 

Oh yeah, and 19 with a vette. How fun is that :D

 

Do this and you will probably lose.

 

Maybe that's why he told me to do it :jester

 

17 with a Vette is even cooler! haha j/k No need to double clutch... just power shift when bangin out the gears.... I dont power shift into 2nd cause they spin... but after that i do

 

every time i change gears, wheather it be backing out of the driveway, rushhour or in a race... i always powershift unless its 1-2...

you forgot to add that

 

Bring your friend and show him this message...

YOU ARE DUMB!

:jester Ok, Fast and Furious rant off..

 

man :confused: I've been driving a stick longer than the age of most of the replyers here and I've never even once heard anyone say 'double clutch' . i think that used to be done back in the dark days, maybe before there was any kind of syncer. the jolt is all yours, once you've been at it a while you be so smooth that your passenger want even know you shifted. and as for the drag race ........ never. as for the down shift from 6 to 3 @ 65mph.... (which i do sence i use 6th at low speed) a good rule is know your red line in each gear and bring your rpms up before you let out the clutch. a side note here, you need to check your friends references :rolleyes:

 

Basically another reason not to skip gears when downshifting(although I do it all the time, but I have 20 years experience) is that you stand a chance of causing the rear axle to lock up from sudden decceleration.

Go find a deserted wet parking lot and rev it up in either 1st or 2nd gear and let off the gas, but don't push the clutch pedal in. You'll see how the backend will want to come around. Imagine that at 70mph!

There have been many times where I'll be cruising along at 60 mph in 5th or 6th gear and I'll downshift to 3rd and hit it. Pretty cool when you can get the back end loose at speed.

Matter of fact just watch this video of mine. After I do the burnout and come back towards the camera, I floored it and let off and you'll see what happens.

http://temp.corvetteforum.net/c4/mrm...lspinslide.wmv