jungy4

I usually look at the speedo and go by this rule:

30 MPH - shift down to 3
20 MPH - to 2 and so on.

cinobyte

so releasing the clutch while in neutral saves the syncros. I honestly had no idea guess i need to read more

justnspace

iTrader: (1)

its called double clutching.
Southernboy had a really good summary on how to do it.
i'll see if i can dig it up

cinobyte

I have been talking to southernboy some very nice guy and very knowledgeable

ez12a

I must applaud SouthernBoy spreading the good news that is Double Clutching.

Too many n00bs on the youtubes saying that double clutching is for noobs or has no purpose in modern transmissions. I tell you this, if syncros were indestructible why have replacement syncros? they absolutely are not indestructible. stories on E46 forums of popping out of gear, etc. It's not limited to only Japanese makes.

Certainly knowing an additional technique does not make one ignorant. NOT knowing makes one ignorant. I laugh at the top rated comments on double clutching videos on youtube. Such ignorance..

http://youtu.be/0j-3xIZK-Bk
^double clutch heel and toe - a seasoned driver can execute these essentially as fast as a regular downshift. Except you reduce transmission wear.

DisgustipatedAP1

No, it only saves the synchros if you revmatch when downshifting.

You can also just normally revmatch during a downshift. If you've done it properly you'll sync the revs and the downshift will be completely smooth, even smoother than an automatic.

Also, taking out the checkvalve (from the slave cylinder) makes downshifting + revmatch a much smoother process.

SouthernBoy

Thank you for the kind words. I'm pleased to know I was a help to you.

SouthernBoy

There is some confusion between the concepts of rev matching and double clutching on many of these forums so I'll try to clear this up for you and point out where they differ.

Rev matching is a technique used to match engine speed to wheel speed when downshifting. It can also be employed when and upshift has been disrupted due to timing being off or when something abnormal has disturbed your upshift. When properly performed, rev matching will significantly prolong the life of your clutch components.

Double clutch is much like rev matching with the added benefit of significantly prolonging synchronizer life when properly performed.


Rev Matching steps (very simplified):

o Remove foot from throttle while disengaging the clutch.
o Begin downshift into selected lower gear.
o During the downshift with clutch disengaged, blip throttle to raise engine speed.*
o Complete downshift and release clutch.


Double Clutching (also very simplified):

o Remove foot from throttle while disengaging the clutch.
o Begin downshift into selected lower gear, pausing in the neutral gate.
o During pause, blip throttle to raise engine speed AND engage clutch at the same time.*
o Disengage clutch, complete downshift, then release clutch.

* When you blip the throttle, you want to raise engine speed enough so that as it is returning to idle you catch it at just the right point when releasing your clutch as you complete you downshift. Too much, and you will feel a jerk. Too little and you will note your downshift sounds and feels much like what most others do when they downshift.

You will know if you have performed these steps properly when you release your clutch and the transition is so smooth, a passenger would not even be aware that a downshift took place.

The major difference between rev matching an double clutching is the extra step of releasing the clutch some, or all, while blipping the throttle as you pause in the neutral gate. What this does is engage the transmission input shaft which in turn spins up the layshaft and meshed gears in preparation of your downshift. You are effectively performing the tasks the synchronizers must do in order for a shift to take place. Rev matching does not do this because you do not release the clutch during the throttle blip. Rev matching does match engine speed to wheel speed in the chosen gear which results in much less clutch wear. Double clutching also does this with the added benefit of reducing synchronizer wear.

ez12a made reference to those who will tell you that none of this, double clutching in particular, is necessary because modern cars have synchronizers in their manual transmissions. When you hear this, you can bet the writer is either young or ignorant of how a manual transmission operates. Synchronizers were first used in 1929 in Cadillacs. And by the 1950's were common place. So they are by no means "new", special, or unique. The fact remains that these techniques will significantly increase the life of these components and this fact cannot be argued. With our TL's and their history of synchronizer problems and failures, doesn't it seem to make sense to employee any techniques you can to reduce the problem?

If my explanation of these techniques is not clear, please say so and I'll try to elaborate more on this.

mau108

Hey SouthernBoy I think you missed a few things in the Double Clutch

First, aren't you engaging the clutch (maybe my terminology's are mixed up) when you are down shifting in to neutral?

Secondly once in neutral you have to release the clutch, rev then clutch in and shift in to the lower gear correct?

94eg!

rev-matched double-clutch

- press clutch pedal
- shift to neutral
- release clutch pedal
- rev engine to proper rpm for desired gear
- press clutch pedal
- shift into gear
- release clutch pedal

It's not as complicated as it sounds and with a little practice, you can get it done in one action.

The real trick is doing all that while applying the brakes. That is called heel-toe. Your using two feet to work 3 pedals at the same time. You will really impress your friends if you can smoothly downshift while braking.

Heres a good example. This guys first shift is just a regular single clutch heel-toe. The second shift is a double clutch heel-toe:

http://www.youtube.com/watch?v=IuoZeuSgEj4

ez12a

Everyday I'm shufflin'


it might look confusing but if you slow things down and think about each movement it makes sense.

also to note "heel and toe" may be a misnomer depending on your style. People use the side of their foot as well.

SouthernBoy

No, I didn't miss anything. Go back and read what I wrote and you'll see I covered what you may have thought I missed. In the event anyone would like a more detailed description of the double clutching steps, here ya' go;

o Fully disengage the clutch.
o Begin your shift to your chosen lower gear.
o Pause in the neutral gate.
o Blip the throttle to raise engine speed and at the same time, engage the clutch.
o Disengage the clutch again.
o Complete the downshift.
o Release the clutch.

cinobyte

Damn Gary got Skilllzzzz