18 Speed Shifter in Semi Truck - Floating Gears or Double Clutching

Floating Gears

For those of you that don’t know the terms, floating gears is the process of shifting without the use of the clutch. It is performed by carefully accelerating and simply “floating” the shifter into gear when RPMs reach a desired level. The clutch is only engaged when starting the truck and for the initial roll forward. Some of the newer trucks don’t require use of the gas pedal to start your initial roll either, so pedal usage can be at an all time minimum with skilled gear floating. Heavy duty trucks have unsynchronized transmissions, which enable you to float gears. If you tried this in your Subaru you might get your teeth rattled.

Double Clutching

The double clutch method is the by the book process for shifting through the gears on your transmission.  It is done by simply pressing the clutch, popping your shifter into neutral, release the clutch, pushing the clutch back in, and shifting to the next appropriate gear. This method is usually employed when you are gaining too much speed going down hill or while climbing uphill. It is safer and will keep you from grinding your gears as you shift. The downside is you are going to have to be pushing in the clutch loads more, potentially wearing it out the bearings quicker. Also, in older vehicles, you won’t be able to smoothly drop the shifter into gear, so double clutching becomes more of a necessity.


At the end of the day, you should do what is best for the truck. Every truck has its own feel and every driver is different. According the EPA a good driver can make a 30% performance difference in fuel over a bad driver. I’m sure the number is similar for preserving transmissions and engine health. Most people don’t even have to think as they are shifting through their gears, especially those who have been in the business for many years. It will be an integral part of driving until automatic transmission can catch up to the fuel efficiency of a skilled driver. Please leave any comments below, we’d love to hear your opinions on the matter. Also, make sure to always stop back in to our homepage for the best semi truck exhaust stacks.