18 Speed Shifter in Semi Truck

The short answer: both techniques work just fine depending on your transmission. There are slight upsides to each depending on your application.

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.

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.

  • Gary

    You may have read this in a book, but you don’t know much about shifting gears. First think about how many more times you slip your clutch disc screwing around with double clutching, and then try to tell me it will last just as long as someone who floats gears. Second clutch linkage wear. I can see speeding up a shafts in the transmission, but don’t I do that same thing when I float? When is this ignorance, justified with a lie going to stop?

    Just looking for some thinking people that don’t just repeat something they heard or read somewhere.

    Thanks Gary,
    A real professional driver since 1978

  • Jim

    I learned to float and it just makes more sense to me. It’s so much simpler than double clutching. Sometimes I’ll clutch out of a gear, but float into the next one. A young guy just started at my company and learned to double in driving school. He has little actual OTR experience but claims doubling is better than floating, but he sure banged that gearbox around good when we drove together! Also says the transmission is out of gear less time with the double clutch. I can’t quite figure that one, but he’s young and knows everything. LOL.