I have been floating gears on mine for years the only time i use it is start stop and backing up

 

sometime I don't use (forget) the clutch..sometimes I grind em..& times I forget what gear I'm in and kill the engine. I just yank, push and pull untill I get it in a hole that will make it move, hopefully it's in the right direction

 

big rigs have no syncros... thats why you have to shift a certain rpm.. i used to do it all the time in the tandem used to drive..

 

12valveater hit it on the head. Semis don't have Syncros, and generally people think that they're saving their clutch when they're "speed shifting" in reality your clutch still wears when you're doing it and often is actually wearing faster. Semi Drivers are pretty split on doing it for the same reason it doesn't really save the clutch, and often gets out of adjustment quickly.

 

I drove big rig for years -- rarely ever touched the clutch after I was out of the low hole, but the transmission design in pickup trucks is VASTLY different than a Road Ranger with straight cut gears.

You can get away with not clutching -- for a while -- then it will come back to haunt you when the syncros are out of the little 5 speeds behind our Cummins.

FWIW, the actual procedure to shift between gears on a big rig is to "double-clutch" -- where you clutch once to pull out of the existing gear, then adjust engine rpms until the two gear speeds match, then clutch again to enter the new gear. If the driver does everything JUST right (rpms must match exactly) the shift will be silent and smooth. If not, the hunt for the proper gear begins with much scratching and grinding until you finally find that gear. It is worse on a moving load like liquids or swinging meat, where the speed of the rig can vary with the movement of the load. Sort of MAKES one into a true driver after a bit... Once you can match the gear speeds precisely, the clutch becomes optional -- just toss it from gear to gear. I could shift faster and smoother without the clutch than with it.

Anecdote... While I had a "professional trainer" riding with me in preparation for the soon to be released CDL license, I drove a bulk milk truck making farm pickups all day on hilly gravel roads, and never used the clutch all day until mid afternoon when the "pro" caught me. He gave me hell for not touching the clutch, and went on to explain the "textbook" definition that I described above. All I said was, "Did you hear me scratch a gear all day long?" He said he didn't care, and that I was an unsafe driver. That was a real WTF day... On my particular route, I shifted somewhere around 15,000 times a day. Using the clutch that much would have blown out my knee after a couple years. I went right back to my way as soon as the dufus was out of my truck.

Note: I DO NOT shift without a clutch in a regular pickup truck, except once in a blue moon for giggles and to show people that it can be done. No real reason to not use the clutch when you have a transmission with syncros and only have to clutch once. Transmission repairs are MUCH higher than clutch replacement, and the clutch will last almost forever if you keep your foot off of it once engaged.

 

Powershifting is more forceful, IIRC.... that's how GM tested the '01 ZO6 to ~3.9s 0-60mph....official reports tested ~4.3s from conventional shifting. Powershifting will beat the **** out of the synchros.

Semi-trucks have un-synchronized transmissions, but modern transmissions are designed to be shifted clutchlessly. In light-duty applications I don't know that it is an okay thing to do. Don't you have to push the clutch in just to get it out of gear?
Just be careful with the synchronizers; if you don't match your rpms correctly you'll effectively be using your synchros as a clutch and needless to say this will induce some intense wear....changing a clutch is still cheaper than overhauling an entire tranny.

 

I'm fairly sure that power shifting is when you hold the accelerator to the floor and push in and release the clutch as quickly as you can find the gears. Which will basically sing the tires in all 4 gears, if the car has the engine for it.

 

Awesome explanation. Thanks man

No I stopped shifting like that the minute I heard it was bad

Good then I'll buy your common rail :tee-hee:

Wait, we're still talking about a transmission here right?

That had me rolling

 

if you really like shiftin without a clutch i guess you could just throw a 15spd in it.....

 

Aw hellz ya! I'll take 2!

But seriously I would if they were cheap and easy to swap