You don't need to double de-clutch with a synchronised box. But you do get smoother downshifts and better pickup if you blip the throttle before downshifting, especially on cars with a narrower power band.

lol I'd like to BLIP this thread up once again. In fact, I started getting overly crazy about it after a friend and I TD'd the Laura TSI last weekend on Hosur Road for the heck of it.

So I tried all I knew during my turn with the TD and every time I downshifted, I could feel the surge of power after a momentary hiccup. Then, it was my friend's turn and BOY! I realized he did something I didn't because the power delivery was highly linear when he downshifted. He told me that he "DOUBLE-CLUTCHed". And I thought it was only for those old huge trucks that haven't evolved yet to include synchros in their trannys.

I did exactly what every motorhead would do, after heading home, GOOGLING after listening to all that my friend told me about the benefits of double-clutching. And how his family-driver had taught em all this technique on the family DRIVING CLASS car - A Premier Paddy!

So, double clutching in modern cars does have benefits. It saves the life on your synchro if done well. I'm still trying to perfect this art by trying and completing this act clean in a split second. But, I felt I must share this with you all bhpians, and am sure will improve the fun in spirited driving!

A normal 4th to 3rd gear downshift:
1. Driving along in 4th
2. Depress clutch pedal
3. Shift into 3rd
4. Release clutch pedal

Usually the engineers match the gear ratios well enough that this should all happen smoothly, but it can't be perfect all the time. The synchros do a lot of work in order to get the drive gear and 3rd gear spinning at the same time, and the wear on the synchros is what will cause that grinding sound over time.

Now, if you want to preserve the life of your transmission, and look (and sound) cool doing it: follow these simple double clutch instructions. Remember, it's called double clutching because you use the clutch twice.
1. Driving along in 4th
2. Depress clutch pedal
3. Shift into neutral
4. Release clutch pedal
5. Blip throttle
6. Depress clutch pedal
7. Shift into 3rd
8. Release clutch pedal

If you did it right, the shifter will slide effortlessly into place with no clicking or grinding sounds. If you followed the directions, but still met some resistance getting into 3rd gear, then you are blipping the throttle too much or too little.

When you blip the throttle with the car in neutral it causes the engine and transmission to move at the same speed. If you blipped it just enough, this speed will be the same as the axles, too, and everything will come together.

An important thing to realize is that the car is not in neutral if the clutch is in. The shifter must be in the middle of the transmission, and the clutch must be released for the car to be in neutral.

If someone has told you that double clutching is revving the engine while the clutch is in, they are wrong. That only does half of the work and does not get the transmission up to speed.

Why does the entire write-up look like a normal Blip-n-shift than double-declutching to me?

Instead of sliding the stick into neutral and than doing it, you match the revs and road speed and then downshift while clutching just once only. You are making it complicated for me to understand brother!

Yes, that's not double-declutching but normal Blip. Or am I missing something here?

You obviously don't own Tatas. On both our indica and safari, esp in the morning, if you want to engage 1st gear, or reverse, you have to do a double clucthing to get the gear in slot.

In days before the invention synchromesh gears, one needs to do double clutching to gets the gears engage without them clashing. This was mostly needed for the heavy vehicles.
But in most of the modern vehicles synchromeshing is provided from 2nd and above and 1st ( mostly) and Reverse gears were left without them as an additional safety factor.
I understand that most of the new generation heavy vehicles have synchromesh gears other than 1st and reverse. Some drivers still use double clutching as old habits die hard.
I had driven Tata Safari and Indica for years and never had to used double clutching.
Please some correct me if I am wrong.

Although I have never driven a Safari but I own an Indigo (Petrol) for several years now. And I may say that I do not ever need to use double clutching while switching to 1st gear. However, for the reverse gear it is even recommended in the owners manual to have a five seconds pause for a smooth engagement of reverse gear.

I know these vehicles have syncromesh gears, however, when its cold I need to do it.
I often press clutch, and try to engage gear. If It does not engage. I leave clutch completely, press clutch again, and then go for it. Most of the time it engages.

There is no "gnashing" sound.

+1. I do the same for the Palio while engaging reverse and it works all the time

Exactly. That's what my last comment in the post states. What you mentioned here is only rev-match. But NOT double clutching. When you plainly rev-match, as you mention, the dog teeth of the collar would have already latched in the slots of the respective gear that you would like to slot into. While all this happens in the tranny, and since you still have a depressed clutch, all you are doing is disengaging the tranny from the engine.

The intention of a manual double clutch while downshifting (although not necessary in modern vehicles since we now have synchros) is to reduce the load on the synchronizer. Synchronizers are expensive to replace and are usually done somewhere around 40000kms.

Pardon me if I've uttered blunder, but hey! this is a forum and blunders ought to be debated and corrected.

On my indica, stock syncros going fine(115000kms), and on the safari at 75000kms they are fine. I do not think you need to replace them at 40000kms

Maybe so. But, I've had to replace them at about 48k-ish on a Zen Estilo. The point I'm trying to make here is WHETHER double clutching can minimize wear and tear, and NOT comparing the life of synchros on different brands.

From what I read from various other forums is that, IT DOES. I'm trying it, and trying to perfect it. Mostly if not always. Whether th effect is going to show... only time can tell.

Here's a link I thought might help aid:
TheSamba.com :: View topic - The Art of Double-Clutching

You obviously didn't notice my avatar pic We have a Tata Indigo CS TDi that's covered 23K kms. But thanks for the tip reg. the double clutching, because I always have difficulty slotting into first/reverse in the morning.

I drive a 2010 Hyundai i20 (Mark 1) CRDi [Asta] and after looking at a couple of YouTube videos tried double clutching while up-shifting. What I felt was (and this could be psychological) that gear changes occur with minimal lag and loss of engine power. In other words shifts seemed much more linear and the acceleration that was lost in the neutral zone was nullified to a certain extent. But all new breed of cars including mine have syncros right ? Any benefits of double clutching in such a scenario ? Any one please care to explain.

When I drive my classic Alfa Spider I always double clutch. For several reasons. It's becoming increasingly more difficult to find good replacement synchro rings for these classic cars, it sounds terrific and I need the practice. I used to drive trucks and in those days many trucks did not have synchromesh boxes so double clutching was an absolute necessity.

A box not slotting into first or reverse in the morning is usually a case of the gear box transmission oil being a bit cold and thick. On many cars first and reverse don't have a synchromesh on these gears.

Jeroen

None. It is that simple.