floating

say, there was a guy trying to get out of his W900 lease. He told me that with a heavy load, it was a little heavy on the sides due to the fuel tanks or something. said if u werent careful, you could lay it over on the side. dunno if that is something unique to the 900 or if he was just BSing me.

as far as floating, i was never 'taught' to float. ended up teaching myself. i do find out that on super heavy loads, i still double clutch till i get movin'. when you start, you will grind the gears. Just remember the truck will tell you when it wants to shift, and don't force it. It should slip in and out just like....well.....u know.

and dont be afraid to rev the engine up. its a truck, not a cadillac.

 

Maybe this is just my inexperience showing, but I was of the understanding that modern trucks are designed for clutchless shifts. The clutch is only needed when starting from a standstill. The fact that "floating" needs a special term seems a little awkward.

If you are rev-matching for up and down shifts then it will slide right in. The clutch is only there to assist in matching the speeds of the engine and transmission when they are off (once rolling). Correct the rpms and it isn't needed. I used to be a bit of a car enthusiast and learned this pretty quickly in the car once I started trying.

 

Manual transmission cars are fully sync'd (at least any of the domestic ones) and much easier to do this with. Even my Suzuki Motorcycle shifts w/o the clutch just fine....

But everyone is right here. If your RPM and speeds are dead on, it will fall in/out of the next gear like butter. It's getting that tweak down pat from removing it out of gear as you come off the throttle..letting the engine settle and then sliding into the next gear up...its all timing. I have found that when I tried to 'think' about what I was doing, I would mess up. It needs to be natural...

 

Hey Dickjones, just wanted to give a you a heads up on the Kenworth W9. For one, this is my favorite truck (studio version). Props to Kenworth for making a beautiful classic truck while also keeping the fuel mileage fairly decent. You can really get more out of it by switching the 8 speed tranny to a 10. It is already set up to do so and is easy. As far as weight sadly it is one of the heaviest trucks out there. As a team (with a large dog, chains and food supply) we were always pushing it. I beg to differ with the rollover facts though. This is by far one of the most stablest trucks out there. Especially when the winds get up there. This truck definitely holds it own! Out of all the trucks the old style petes, international 9900's and W9's are some of the best for non-rollovers! The downside of this is the turning radius and also if you are a new driver the stacks can pose a problem when backing. One reason you see new drivers backing with the door open. The cab is slightly pinched in with the stacks located right where it tapers inward. This makes it hard to see around the stacks. Plus it is a little tricky wedging in between the shifter to get to the sleeper. All worth it though! The W9 also has the largest bed (on the bottom bunk). If you have a choice in buying a good over the road tractor this would be mine. You do need to keep an eye on your steers because of the stretched frame. The frame actually flexes and can cause extra wear on the steers. This is a very dependable truck and the only other mechanical issue you need to keep an eye on is the EGR and fan hub bearings. On the plus side this truck probably holds it's value better than any other truck out there! If you are thinking of buying one of these this would be my top choice!

 

So I floated gears all weekend - at least on the upshifts. I am not comfortable floating down the dial though...I have been able to do it, but I dont like being in neutral during this and if I miss the shift - well...
I got floating down pat months ago, but started double clutching so I wasnt too rusty with that. I have tried skipping gears up/down and have had some decent luck with that - but I dont usually even try...

It's fun to do when you got the right timing down pat. They just click one after the next, even when changing ranges (low to direct for example). Got to let the engine settle just the right amount and "CLICK" she just falls right in...it's awesome during turns too..especially the kind with long approaches where you HAVE to shift a few times...

 

Newbies,Wannabes, and anyone else please note:

Heavy truck transmissions do NOT have synchronizers!!!!!!!

This is why you are taught to double- clutch.

Floating is fine when you have a bit of experience but yes, you can blow up a gearset if you #&%# up and you will get your butt fired for destroying equipment.

 

Actually most do have some synchronizers just not in the type of mechanism as a synchronous transmission because the gears non synchronous transmission are always in mesh. Since the gears in a non synchronous transmission are always in mesh you cannot damage the gears, rather one would damage the shift collars, or shafts, which in turn can break and damage gears, but guess what? A sloppy shifter is a sloppy shifter regardless of whether floating or double clutching. Until one becomes "one with the truck" and fully understands the relationship netween gears, speed and rpm, they will never become a good shifter. When they do have this understanding they will understand that what is needed to make a "perfect" shift is the same floating as it is double clutching (Other than depressing and releasing the clutch twice). In other words if one can DC and can't float they likely aren't shifting very well double clutching. Double clutching does help some driver's timing so they would be one exception.

We teach students floating first as a means to this end. After they have mastered floating we then introduce double clutching, and then double clutch from then on, usually for the next 5 weeks. In the past 15 years we have trained approximately 60 students per year, and have had no transmission or clutch related problems. With approximately 900 total students (Different drivers), well over a million miles and literally several thousand shifts per day we feel this works well for us. On the other hand I am not so arrogant as to believe this would always work as well for others.

In terms of what one should do on the job my opinion is that if a company insists on double clutching then you should do what those paying you want you to do.

Best regards

 

Great post! ^^

Sort of along that line of thinking: I started out double clutching (in school, early training, etc) and I always had to sort of half-think about what I was doing each shift to get the rhythm right. I never really had issues with when to shift, just had problems getting from one gear to the next. (Also had some trouble picking the right gear on a fast slow down, going from 8th to 6th, etc...but that's a different issue.)

When I got into the truck with a second stage trainer that encouraged me to try what I felt like trying ("Just don't break my truck," he said) I found almost instantly that shifting was orders of magnitude easier and more intuitive.

Your explanation of the mechanics of the typical class 8 transmission is one of the best I've ever seen, just in terms of low jargon, high logic terms. It's good to see a teaching philosophy that's based on reason and logic, and pursued confidently.

Definitely on board with the idea that good shifting is a "one with the truck" phenomenon that improves only with butt-in-seat time (if the basic sense is ever gained).

 

Yup, I agree about your tranny info BUT ( aw c'mon, you knew there was gonna be a but) my concern is with the newbies/wannabes here who are saying "don't need to know double-shift always float" or "just like my car". 99+% of these have no frikkin idea (or at best only hazy) idea about what goes on in a tranny. Miss a gear while floating and they have no clue what to do. Rev, rev, grind, grind, oh ####e I just went off the road!!!

Thus I maintain.... Learn to double clutch first and worry about floating after.

 

If a driver floating has no idea what to do when he "misses" a gear, he doesn't know what to do if he misses one DCing either. If he is on his way to being "one with the truck" eventually he will realize that if he misses a gear whether double clutching or floating, the fix is the same (Stay off the clutch and align rpm's), then he can either float it in or clutch it in (Considering that the truck speed has not changed such as to require another gear selection).

Usually when someone misses a gear on an upshift it's for one of two reasons. They allowed the rpms to fall too low with the fix being to "gently" raise them back up (Reving usually results in running by the alignment whether DCing or floating), or they did not allow (or they hindered the rpm's from falling), for which the fix is again obvious. Even a great shifter is going to screw a shift once in a while, but the difference between a great shifter and a not so great shifter is that with a great shifter he will make the fix so subtly that no one in or out of the truck would know that an error was made or that the fix was made. I often say that the brains in the shifting operation is your right foot. It will if allowed to (And not hindered from) develop a memory, and it can be a really sensitive memory (Or not).

Best regards