Proper Downshifting Techniques

Here's something to think about relating to downshifting to a stop:

Consider how long you'll be in gear and decelerating vs time spent shifting. In the higher gears, it takes a bit of time for the truck to slow to the next shift point, and splitting to keep the rpm up helps you slow faster. But once you're out of the right gate, you're better off shifting whole gears instead of splitting. The truck will barely spend enough time in any one gear to get the boost up and the Jakes fully working. It's more productive to just do whole gears and spend more time decelerating than shifting trying to max out the Jakes.

I generally always used whole gears all the way down after an initial split to 12 or 17, and only split if I misjudged the rate of slowing and needed a tad more retardation. And rarely ever downshift to low side when slowing.

 

Thanks for all the replies. I have a lot to learn and honestly believe I'll learn better on my own without eyes on me judging everything I do.

I have a question about winter driving as I live in Canada. Do you use the inter axle lock when driving in snow and icy conditions? If so, can it be used at any speed?

It's the one on the left in this photo.

https://www.thetruckersreport.com/truckingindustryforum/media/20221007_110626.21930

My trainer said you DO NOT use it unless you are stuck somewhere and disengage before driving away.

 

I only run with it engaged in marginal conditions, where you're constantly fighting to keep traction. It can be used at any speed, just make sure to never engage while a wheel is slipping.

The axle locks (the right 2 buttons) are the ones that are dangerous and should be unlocked ASAP, as they can limit your directional control.

 

Interaxle lock won't hurt anything. I wouldn't run it on dry pavement but on dirt or snow its fine.

Look at it this way: would you rather spin out, then put in the interaxle and try and get 140k lbs to move again from a dead stop with less than ideal traction? Or be able to (hopefully) drive right on through with no issues?

 

Not to mention that you're far better off locked up than running down the road slipping all the time. The last couple generations of rears handle it better, but doing that in an older truck flings the lube off of the power divider resulting in premature failure.

 

Only lugging 80k around I downshift 9-8-7-6 and by then I'm at about 20mph.

 

Um, you don’t need to half shift on downshifts. I only run 80k but that seems excessive. Treat it like a 9 speed on downshifts. You don’t need to downshift before stop signs and sometimes knowing how to catch a gear at a given speed is more useful than performing the full downshift. You should be able to glance at your speed, know the desired gear and RPM’s, and select that gear even if it is out of order. Of course this is once you get familiar after a lot of miles.

 

Do it how your trainer wants it done until you get your solo truck. I would not downshift as much as you are doing. I would downshift and brake because a transmission, and clutch if you use it, are more expensive than brakes. If you can downshift without grinding you don't need anyone's shifting advice. You are ahead of the class. No sarcasm intended.

 

You could just have a particular trainer that's being hard on your case, I'd just go along with it specially if you depend on him giving you the final approval, I know it will test your patience out, but if hes not asking you to do something that is down right dangerous then just go with the flow. When he's gone just go change the gears how you prefer. Avoid confrontation if at all possible again you need this guy to give you approval to go on your own, so just chill out. For down changing there are a range of different variants involved, the kind of hp your engine has, and the type of engine you have, the angle of the grade your climbing, all make a difference as some engines call still pull at very low revs ( less than < 1400 rpm) just remember if you change to soon you need to be going slow enough to be able to get the next lowest gear in, so in some cases you do need to let the truck slow right down before changing, if you have a 13 or 18 speed sometimes you can just split the gear without actually going down an actual gear. If its a slight grade I'd just flick the spitter and that's enough to keep going without changing an actual gear but that's just my style there are no set rules to this gear changing, some like to not use the clutch, while others choose to double clutch, in the end you do what works best under the circumstances.