Double De Clutch Technique Explained.

Double Clutch Gear Shift Technique.

You’ve probably heard about it, but if not, you may be thinking what the dickens is double clutch?
If you are old school, this will be nothing new to you, but there’s plenty of people out there who don’t understand the technique.

If you know what a crash box is (No synchro) then you would know that the Double De clutch technique is required in order to change gears correctly, and it is normal for the drivers of veteran and vintage cars fitted with early manual gearboxes. (Crash box)

The early manual gearboxes had no synchromesh and required a special shifting technique known as double De clutching… and it goes something like…. Well, imagine this, your’e driving along in top gear with a four speed gearbox in your car, then you need to shift into third gear…. so the action is …. clutch the neutral (Press clutch in) and shift the gear lever into neutral…. Clutch out, blip the throttle to rev match, then you clutch the gear, to finally shift into third gear…. then release the clutch (out), and hopefully the gears will not crash or graunch… And you’ll have a huge smile if you got it right.

The technique can actually be practiced in a full synchro box, but you’ll have no idea if you are doing it correctly until you actually drive a non synchro manual gear box,

If the process sounds complex and a bit long winded, you’ll be pleased to know that in practice it is actually is quite rapid and smooth going, (Until you get it wrong) and a very pleasant way to change gears, and with lots of practice, it becomes an art form.

Some background history-Synchromesh
In 1929, the Cadillac was the first vehicle to feature a full synchromesh gearbox system, similar to the synchronised transmissions in modern vehicles.

When the writer was very young, he was lucky to be taught this technique by his father while learning to drive the old KM series Bedford farm truck, the gear box of course was a four speed full crash box…. and Oh my, the painful mechanical sounds of protest if you got the clutch action and gear change horribly wrong, but one soon learned the correct timing and sequence of double clutch gear shifting technique.

So, out of pure interest, we decided to create some video content to explain and demonstrate the process to help you to fully understand what Double De clutch gear shifting a non synchromesh gearbox is all about. We hope you enjoy.

So here again, the curious might want to know about the video/audio recording aspect of this project.
A special temporary cam rig was fabricated using the TIG welder to hold the camera with the point of view and focus at the level of the gear change lever. The base of the rig was temporarily screwed to the fire extinguisher mounts, and the top part triangulated and temporarily fixed to the LHS dash mounting screws, it all worked well to hold the camera firmly in place. After the shoot, the rig was removed and everything returned to normal, no one would ever know what had been there.

The sturdy camera mounting and holding rig.

The bits and bobs used for video/audio recording. The camera is- GoPro 10.
Setting up to create some videos of your drives or car is not cheap, but when you get familiar with the gear, it all starts to fall into place.