therckid

alright guys, just like my toehr topic about auto vs. manual. my n00d friends dont belive me that in modern day america there is no such thing as double clutching becuase there are syncros. Please help me find a way to tlel these people how it relaly is.

They're n00bs, they watched Fast and Furious and believed the double clutching bs.



Shane

Beefy89

You only double clutch if the transmission doesn't have synchronisers..

AlkyIROC

Agreed.

The addition of syncros did away with having to double clutch. Try driving a chev pickup with a truck 4 speed. First gear (hardly used and usually refered to as Low) isn't sycronized and you'll never drop from first to low without double clutching and even then you can't be going very fast because it's such a low gear.

Even highway tractors with 18 speed trannys are all syncronized. Many drivers don't even use the clutch to shift the gears however it just keeps me employed having to change worn out syncros and gears from that kind of abuse.

Brent

iTrader: (1)

When did this happen?

Its been several years since I drove, but the 9 speed Eatons I had fun with definitely didn't have any synchros.

Beefy89

Actually those 18 speeds AREN'T synchronized, you eventually just get a feel for the RPMs and can slide it into the next gear when the engine speed is close to the speed of the input shaft on the transmission..

scottland

What the fast and furious was trying to say when they said "double clutching" is "power shifting"

which is where you never take your foot off the throttle when you shift. It gives the effect of launching the car at every shift. But it is very hard on your drivetrain, and if you don't have a rev-limiter, i wouldn't suggest it.(missing a gear=scatter zone). But none-the-less, it is the fastest way to get down the track with a clutch-type manual.

Truckers don't ever double clutch. Even without a syncro-ed tranny. If they did, they would replacing clutches weekly. They just shift without the clutch, i do it in my car all the time.

The only time i every hear about "double clutching" anymore is with high-reving 2-strokes, some people will blip the clutch in first to get the rpm's up faster.

Beefy89

Double clutching doesn't wear on the clutch at all..The reason for double clutching is to match the speed of the engine with the speed of the transmission so that you can shift into the next gear. And two stroke diesel engines don't rev higher, the cam and the crank are on a 1:1 ratio which gives the impression that they are reving higher..

scottland

I am well aware of what double clutching does. and every time you push the clutch in, you are wearing it out faster. truckers shift without the clutch, they pull the transmission out of gear into neutral, then lower the rpms until it falls into the next gear (upshifting) They usually only use the clutch to get the vehicle moving. truckers shift a couple hundred times an hour, and if they used the clutch every shift, that would be pretty pricey.

The double clutching you are thinking of is where you push the clutch in, pull the shifter out of gear, as soon as it is in neutral, release the clutch halfway, that allows the clutch plate to grip slightly and get it spinning, then push the clutch in all the way, and shift from neutral into the next gear.

Double clutching is also sometimes used when refering to "heal-toe" downshifting. which is used when downshifting around a turn. as you are braking with your right toe, you push in the clutch, pull the shifter into neutral, then release the clutch halfway, at the same time, swing your right heel over to the gas pedal, blip the throttle to match the rpms, then push the clutch back in, shift into the lower gear, and release the clutch. when done seemlessly, it is the fastest way to downshift around a turn.


and i wasn't refering to 2 stroke diesels, i was refering to 2 stroke dirt bikes that rev up to 13 thousand rpm. so i would conders that higher.

Beefy89

Let me start by mentioning that I am a 41 year old Diesel Mechanic who works on light, medium, and heavy duty trucks for a living..

[QUOTE]Originally posted by scottland
[B]I am well aware of what double clutching does. and every time you push the clutch in, you are wearing it out faster. truckers shift without the clutch, they pull the transmission out of gear into neutral, then lower the rpms until it falls into the next gear (upshifting) They usually only use the clutch to get the vehicle moving. truckers shift a couple hundred times an hour, and if they used the clutch every shift, that would be pretty pricey.

Misuse or abuse causes premature clutch wear, not double clutching.. Truckers who shift without using the clutch do so because it is faster than using the clutch..

The double clutching you are thinking of is where you push the clutch in, pull the shifter out of gear, as soon as it is in neutral, release the clutch halfway, that allows the clutch plate to grip slightly and get it spinning, then push the clutch in all the way, and shift from neutral into the next gear.

I don't know what Hollywoods definition of double clutching is, but in a medium/heavy duty diesel truck application you push the clutch to the floor to disengage the the clutch, and engage the clutch brake, select a gear, engage the clutch, when you reach the desired RPM you disengage the clutch(not to the floor or the clutch brake will stop the rotation of the transmission), shift to nuetral, engage the clutch, rev the engine rapidly, disengage the clutch, select a gear and engage the clutch again.
Allowing the clutch to slip leads to premature clutch wear..

AlkyIROC

Since many truckers hate to use the clutch when shifting I tell them to at least use a little bit of clutch when taking the tranny out of gear between shifts. The gears have a slight taper on them so that they are forced to stay together. By releasing the clutch, the load is taken off the gears so they can be pulled apart easier. They can match the speeds with the engine rpm to jam them into the next gear if they want. That will still wear out the syncros and gears but isn't as hard on shift forks as trying to pull them apart when there's a load on the gears.

Very few trannys either Eaton or Spicer do not have syncros. They look nothing like a syncro in an automotive tranny. They actually look more like a cup and cone posi with a friction material running in a cone.

Don't want to shift? Buy a truck with an Autoshift. 10 Speed manual transmission with a clutch. The clutch is used to start and stop. You put the range selector in D, let out the clutch and a computer does the rest. up and downshifts, controls the engine rpms to match the shifting, decides what gear you're supposed to be in not what you want to be in. Now anyone can be a trucker.

Beefy89

Sorry my bad.. Yes block or cone and pin synchronizers, which I always refer to as SLIDING CLUTCHES..
And yes as long as truckers keep shifting without clutching, we'll always have a job.

MrDude_1

ask your friends what double clutching is.

they probly dont even know.




my spitfire has a non syncro first gear.. if i want to down shift into it, i have to blip the throttle just right... its not hard to do once you get used to it.
when i started riding sportbikes, i got in the habit of matching revs on the downshift.. its not hard on bikes since you can easily move the brake and clutch at the same time... well once i was doing it on the bike without thinking, i found myself doing the same thing in the car..