Double clutching to speed up the transmition? wtf?
 

I was talking to my friend and was wondering if he double clutched and he said yes. I was like well stop your just going to wear out your clutch because your syncromesh gear box was made to where you don't have to do that. And he says well I do it to speed up my tranny so I don't grind gears cause my syncros are messed up. This isn't poible is it? I go you mean slow it down and ha said no I mean speed it up. Its physics dude. By puting the tranny in neutral and letting the clutch in and out speeds up the tranny? My ass! There is no way is there? T ake a CD and spin it around a pencil, Unless you use the force of something to speed it up it will Slow down. So should the tranny right. I was told by several people it slows down the tranny when you double clutch. I'm I just thinking wrong or is my friend an idiot?
Charles

Look who's talking (about physics) :rolleyes:











































But, yes, you are right (for once) and your friend is wrong (i see where you get your mechanical 'genius'). Double clutching is for older transmissions that dont have syncros so that the gears can line up at the same speed w/o meshing harshly.

HAHA!!!! I'm right and hes wrong!!!!! HAHAHAHAHAAAAAAA! I told him that he was wrong he called me and idiot and I'm right! HAHAHAAAA! Thanks Dre thats what I wanted to hear. You just made my day man. Have a good one.
Charles

Double clutching is only needed to keep driving with totally worn out syncros. Double pedal (heel-toe on the gas-brake) downshifting on the other hand is very useful entering a high speed corner..
bill

Uh, he said his synchros were messed up. Therefore, he'll need to double-clutch in order to prevent his gears from grinding. And YES, he's "speeding his transmission up". The tranny has two "sections" - the section between the tranny input shaft and the gear, and another 'section' between the gear and the output shaft (with the 'gear' here being a separation point). When he's downshifting, the first 'section' is spinning too slow - when he engages the clutch at a higher RPM (than his previous gear) he's (guess what!) speeding up the first 'section' in order to more closely match its speed with the rear 'section'. In an incredibly roundabout, nontechnical way, that's what synchros do - his synchros are bad, so he must manually replicate their functionality (JUST ASK A CLASSIC FERARRI DRIVER!!! :mad: )

There's no gear reduction between the engine and the aforementioned first 'section', thus your initial refutation does not apply.

*sigh*

So to answer your question, your friend is right, and you're "thinking wrong". But I think I'll refrain from calling you an idiot, since you're willing to learn - just be careful about calling people idiots when you don't really know what you're talking about. :)

Brandon

Well the thing is that his syncros are fine and he thinks they are bad cause he grinds gears and can't get it into gear sometimes because he misshifts. At least I can drive my car without grinding any gears.
Charles

thank you brandon you wrote all of that so i did not have to

james

Uh, guess what happens when your synchros are fscked up, peacekeeper? The two "sides" of the tranny are spinning at different rates, and the gears can't mesh correctly.

And then the tranny grinds on shifts.

Brandon

Um.. anyone can grind gears.. your gears grind as soon as the synchros wear out. Hell, my even grinded from 1st to 2nd gear. Know what I did to fix that problem? Put red line in it.

Brandon is right...

and don't call someone an idiot when you're not right... but you are trying to learn.

blah
 

I just bring my revs up to match as closely as possible the speed of the rest of the drivetrain then I let the clutch up and that way the RPMs don't change noticibly on the tach and the clutch gets very little wear..

I can't afford to be wearing out clutchs by using them to brake or acclerating before having the clutch up all the way.

Redline works in mysterios ways.

You're missing the point, Prax.

You've got to spin the the 'first half' of the transmission before the gears will mesh correctly. Normally, the synchromesh (think about that word - synchronized meshing) gearbox will spin that part up for you. But if your syncros are dead, it WON'T, and thus, you NEED to double clutch on downshifts.

ARGH!!!!!!!!!!!!!!!!!! :mad: :rant: :madfawk:

Brandon

Poor Brandon.. :)

I gave up a while ago.

PaulC

wait i thought he was double clutching on up shifts?

post whore

I double-clutch on downshifts in order to have fun and put less wear on the clutch disc.

It does wear out your release bearing slightly quicker though...

Double-clutching isnt that good, and I wouldn't recommand it, unless your synchros are pretty bad, and you have no other choice.

stop watching the fast and the furious!

OMG I'm going to CRY!

peacekeeper
Offline! 06-20-02 10:34 AM This person is on your Ignore List. To view this post click [here]

Actually you can upsift and down shift without the clutch by matching the "front half" and "back half" of the trans by increasing the engine speed. BTW ever watch nascar. They shift with NO clutch for all but 1st gear.

When down shifting you will need to speed up the "front half" to match speeds (by giving it more gas in neutral, clutch out) on upshift you will need to slow down the "front half" of the trans to match speeds (by reducing the rpm of the motor when in neutral which nearly eveyone on the planet does instinctively).

Did I say slow down? Yup

I know what happens when the syncros are messed up but I am TELLING YOU THERE IS NOTHING WRONG WITH THEM!!!! He grinds gears all day long and when I drive, I have no gear grind in that damn car. They are fine, I didn't call anyone and idiot, I was called the idiot, and I was asking if he was. Alittle deductive reasoning here would be nice. Read the first few posts over again and you should get the picture. I still don't se how letting out a clutch in nuetral and then pushing it back in is going to speed up a transmition. I'll have to take one apart.
Charles

P.S.
What the heck does that mean Adam? Your not making much sense, you said you were going to ignore me so please don't post on my threads.

You make sense Thaniel. Thats what I thought a double clutch would do. Like the clutchless shifting.

Brandon/No7Yet has it right.

Christi said:
Which I highly disagree with. It has its place and time, wether or not the syncros are worn. Engine speed matching to the drive train through double clutching allows a much smoother shift, rather than just jamming it in.

And smooth is the way to go when doing any sort of high speed or performance driving. Keeps the body planted to the ground much better than just jam shifting and hopeing the syncros are good/up to snuff.


And Peacekeeper is draining my brain cells, I can't read anymore of his posts

Obviously if they are talking about both upshifting and downshifting, they are both right, and both wrong. It all depends on which way you are going. When upshfiting, there is no way in hell that you are going to speed up the tranny's input shaft by double clutching, and when downshifting, you will never slow down the input shaft by double clutching.

My preferance/habit, pull it out of gear with the clutch engaged, and put it into gear with the clutch disengaged. makes for one very smooth, very fast, easy on both the clutch and synchros, shift. It does require that you be able to feel, and more importantly predict, the exact moment when there is no pressure on the dog teeth, but it comes quickly with practice.

Hm, I must be confused then. I always thought double clutching wasnt good for the clutch .... I guess I'm wrong. I'll admit that.

Double clutching on upshifts does slow down the input shaft. When double clutching on downshifts you have to blip the throttle when the shifter is in neutral and the clutch engaged. At that point the input shaft is directly connected to the flywheel and NOT the output shaft, so as the flywheel spins up the input shaft spins up at the same rate.
The biggest misconception about gearboxes is that the gears on the input and output shaft are disconnected except when in that gear. This is untrue. The 1st-5th gears are always directly connected to each other and spinning. The gears on the output shaft aren't spinning the output shaft, they are spinning AROUND it. It is the syncromesh gears that are connected TO the output shaft. When the syncromesh gear is pressed into the the gear selected by the gearshift, that is when the car is "in gear".
Double-clutching is unecessary in a syncro-gearbox, but it doesn't hurt anything. And if your syncros are going out it will help you prevent gear-grinding. But at the same time you can heel-toe, or blip the throttle on downshifts WITHOUT double-clutching. Without double-cluthching you just have to blip the throttle a little more, as the clutch is in when you blip without double-clutching so the flywheel is disenaged from the clutch.