Do you let off the gas completely when changing gears?

A five ton semi! Really?Give me a break.A maxed out semi is 80,000 lbs,for single trailers.

I've driven semi's, single trailers,doubles,as well as triples,all my life hauling everything from fuel to groceries 'for small companies,to being a Teamster road driver.

No,you don't have to use a clutch.I can come to a 4 way stop and although NOT stopped completely,but barely rolling slip it into a pulling gear and head on down the road.Have been doing it forever.

Some,newer model vehicles it is real difficult to do this if not impossible.

They no longer use friction clutches in them ,but rather fluid clutches,which definitely makes a difference.

When you up shift,allow the RPM's to fall back to where they would be if using a clutch and you'll FEEL when to slip it into the next gear.Downshift,letting the motor with your foot off accelerator slow you when in the highest range for where you would normally shift to a a higher gear ,or just a little below that you can safely slip it into the next slowest gear.

All this comes with experience behind the wheel and understanding how what your driving operates,watching and paying attention to RPM,when you drive it.Until then you are well advised to use the clutch.

Not necessarily. Technically you don't have to but some vehicles under heavy towing for instance require you to double shift and speed the engine back up to prevent a stall when changing gears. This is not the case for normal cars and new vehicles especially. If the car has a tachometer then maintain an engine speed of around 1000 to 2000 rpm between shifts. With some practice, you will learn how and get the feel for it. Every car is different.

You ALWAYS completely let off on the gas when shifting up. If you are shifting down, learn the technique of double clutching to prevent excessive transmission wear. NEVER shift down to a gear lower than you would at that speed. If you do, you will end up replacing even the best transmission after only a few miles. I know. I had lent my car to someone who didn't understand, and shifted down to 2nd at 70... saying, "I didn't let out the clutch." but... the clutch components and transmission were badly over-speed, and it failed. It isn't designed to go to 40,000 RPM. It's not a jet... it's just a car.

I have a 2008 g37 manual. Not the easiest to shift. I always had trouble shifting smoothly and I already had it for like 6 months. I just found out today that the best way to shift smoothly is to let go of the gas completey but still rest your foot on the pedal very gently while your shifting. Feels Smooth Like butter 👍🏼

Depending on how sensitive the throttle is I either let up completely (very sensitive throttle) or not (controllable throttle). The idea, whether upshifting or downshifting, is to match the engine speed before letting out the clutch and if you completely lift off the throttle you will lurch when you let out the clutch as you go past the match speed with the engine still decelerating rapidly.

Double clutching is not needed on transmissions with synchronized gears. You let up on the gas to prevent the engine from over-reving. After you select the next gear, you apply gas as you let up on the clutch smoothly so as to match the engine speed with the clutch plate speed. I would be reluctant to not use the clutch for fear damaging the transmission. It's not that big of a deal to use the clutch.

I'm no expert on the matter but I always let off the gas completely. You can still make a smooth transition doing it that way but it might take a little getting used to.

Yes, but I have it down so well after 35 years that I can drive anything from a motorcycle to a 5 ton semi tractor.

The bleeding:

https://www.youtube.com/watch?v=hJtJUVyEyYY