Floating Gears vs Double Clutching
If you're a professional truck driver, a racing enthusiast, or even just a Vin Diesel fan, you've probably heard the terms "floating gears," "double clutching," or even "granny shifting" used to refer to the various ways a driver with an asynchronous manual transmission can control their clutch and shift gears effectively. While most CDL training courses and schools have a strong preference for the safest method, there's a massive community of truckers out there who swear by the less-orthodox habit, claiming it improves the lifespan of your clutch, gearbox, and transmission, or even provides noticeable mileage and performance improvements— when the technique is performed correctly, that is.
What is Double Clutching?
Double clutch shifting is considered the textbook standard way to operate your semi-truck's manual transmission. Some would even argue that it's the only truly safe way to do so, and if you're driving a company vehicle you're sure to have heard a few "polite" suggestions to use this technique despite whatever the reality may be for drivers on the road in your area. Why do you have to double clutch a semi? Its supporters, (and most transmission manufacturers,) suggest this over single clutch operation, which is the big rig equivalent of standard "granny shifting," in order to briefly re-engage the clutch. This takes the weight of the vehicle off your gears and attempts to sync their RPM before completing the shift into gear.
How to Double Clutch a Semi-Truck
Well, what does it mean to double clutch then? It's far easier than it might seem to be. You simply press the clutch, pop your shifter into neutral, then release and push the clutch back in before shifting to the next gear. This technique really shines when you're gaining too much speed on a downward slope, or struggling your way up a steep incline. Giving them a brief moment to reorient lets your gears' RPM match your overall speed and easily stops damaging grinding that can eventually mean a death sentence for your bottom line. Of course, this comes at the cost of depressing the clutch twice as much as you normally would, and in older vehicles your ability to smoothly drop the shifter into gear may be limited, making double clutching a necessity rather than a choice when operating these rigs.
What is Floating Gears?
"Floating" your gears is simply a form of clutchless shifting. By changing gears without a clutch, you obviously limit wear and tear on your clutch system and, with skill, shift just as easily as someone employing the double clutch method. It's a common anecdote among supporters of this technique that some drivers can go a hundred, two-hundred, or even a thousand miles without needing to engage the clutch more than once or twice the entire way. This definitely takes more experience, and requires you to be intimately familiar with the way your rig operates, because a poorly floated gear shift can do some serious damage to your transmission or gearbox rather than making anything easier for you.
How to Float Gears in a Semi-Truck
This one is a little more difficult to explain, since so much of it relies on feeling out the next gear. Even its most staunch proponents suggest shifting with the clutch until it's second nature before trying to learn this technique. The easiest way to think about is that you're manually matching your RPMs to your truck's speed, and then you just set the shifter into gear when the opportunity presents itself. When upshifting, you'd accelerate, take your foot briefly off the gas, and gently ease the shifter into place before putting your foot back down. Don't force or yank it, guide it with the end of your hand or fingers. This is only possible because of the unsynchronized transmission in the first place, and for that same reason it's even more difficult to execute properly on an incline. There are tons of great videos and guides out there for a first-hand look at this technique in action, we'd recommend doing some research before testing it out!
Floating gears is considered an advanced technique, and it might become less common with major manufacturers starting to introduce heavy-duty automatic transmissions as standard. No matter how fancy trucks get, though, it remains a great way to drive comfortably and show off a little while you're at it.