What are “granny shifting” and “double clutching”? The right method could save you thousands
A DRIVING expert has explained the difference between “granny shifting” and “double clutching” and the right one could save you thousands.
Car nut Michel Ehmke, from Germany, took to YouTube to show other motorists the proper way to shift down the gears.
In the video, he hit back at social media commenters who accuse him of “granny shifting”.
But many might be surprised to know that this term, often hurled around as an insult, refers to what most drivers would consider a normal downshift.
To give an example, if you were shifting from second to first gear, the best-known method is to press the clutch pedal, move the gear stick from second to first and then gently release the clutch before going back onto the accelerator.
However, this common practice is slammed by petrolheads as too basic and bad for your motor.
To figure out why, it’s necessary to understand how the gears work.
When you move the gearstick, this shifts a small cog along the output shaft (which is what spins the car’s wheels) and pushes it into the cog responsible for a particular gear.
This causes the gear to spin while connecting to a corresponding cog on the countershaft, which itself is connected to the engine via an input shaft.
The easiest way to think of it is like a three-stage circuit, which only puts out power when all three components are connected.
When you let go of the clutch, that connects the input shaft with the countershaft and when you use the gear selector, that connects the countershaft to the output shaft.
If all that happens, the rotation of the engine is transmitted across all three shafts to the wheels.
However, when you “granny shift” this does not take account of the fact that the output shaft and countershaft are spinning at different speeds, which can lead to gear slippage (where the two cogs fail to mesh properly).
The effect of this can be to increase the wear and tear on your transmission as the gears struggle to align their speeds.
Instead, Michel recommends “double clutching” as a better method for downshifting.
Double clutching makes downshifting into a three-stage process instead of just blasting down through the gears all at once.
First, you press in the clutch and move the gear stick to the neutral position.
Then come gently off the clutch and coast in neutral (while braking if need be) and give a quick press of the accelerator to increase the revs to roughly where they were before the gear change, also known as “rev matching”.
Finally, press the clutch down again and shift into the gear you want before releasing the clutch and driving on as normal.
By doing this, you increase the speed of the engine’s revolutions (revs) to match the speed of the output shaft, making it easier for the gears to mesh.
Doing it this way could mean big savings in the long run, as transmission damage caused by improper shifting could require a replacement, which can cost over £1,000.
This is less of a worry for modern cars which mostly include synchronisers.
These components come into contact with each other just before the gear cogs and regulate the speed of the three shafts automatically, making double clutching less necessary than it is for older models.
Nonetheless, replacing your synchros can still be expensive, so it remains a good method to reduce the stress on your transmission.