Downshifting at 800 - 1100 RPM

A general rule is that for every 5 mph you should shift up 1300/1500rpm. When your rpm drops to below 1200/1000 shift down. Now all of that has to do with normal operation on flat ground. Climbing you will let the rps climb a little to allow for loss of rpm when shifting. Down hill you will down shift sooner so not to allow rpm to fall off and lose power. When I was teaching I would tell the driver to use 25mph as the starting point for High or low 25mph is 5th gear below that speed down shift above that speed up shift. Again all depending on road conditions. Matching speed is finding the point where you can shift. 25mph 1400rpm shift 30mph 1400rpm shift. Down shifting is the same idea. I hope that helps and remember all trucks have some deference in how they work so time behind the wheel will fix you.

 

its really quite simple,
think of gears as a stairway top end of 2nd = bottom of 3rd
engine speed is your rpms road speed is rpms coming back thru drive train to the tranny. Lay both hands flat on the table fingers spread and facing each other those are your gears left hand engine speed right hand is road speed , now imagine your hands rotating like a drive line. Those fingers have to slide together smoothly to keep from grinding , if the fingers go between each other your in gear. When down shifting go to neutral , and as you bring your rpm's up slide it into the next lower gear , catch it as the r's come up. after a while you will get the feel of that truck , each one is a little different.

 

I had the exact same question,when I got out of school.I have been teaching myself.Don't fear the shifting,you will get it.Just keep it between the lines.

 

On any truck , you have a shift range , that's the rpms... the sweet spot where the gears mesh... say 1300 low to 1500 high you acelerate to 15 shift and it goes into gear as the rpms hit 1300. This is the reason for the double clutch is to let those rpms match up. So you develop a rhythm ( cummins: Shift neutral 2nd, shift neutral 3rd) soon you can do it without the clutch.
Downshift is reversing the pattern.
So its a small throttle tap when you hit neutral and catch the lower gear as the rpms hit 1500,

most folks take the rpms way to high right off the get go. Remember a diesel uses only a couple hundred rpm's between each gear

then let off the gas and let the truck slow , maybe use some brakes if needed and then grab the next lower gear. You are usually gonna brake or jake brake.
This rhythm changes with every type of motor.
A cat engine is like one thousand one , 0ne thousand two , one thousand three. Slow , and old two stroke detroit is like foomppp!!! No rhythm they are a fast shift. A cummins is like a slow bing bang boom. Think in those terms and it gets easier. And always the downshift is catching those rpm's on the rise. The older cummins had , hmmm, 17-19 shift range the newer are alot lower. Say 13 -15 somewhere in there.
If you miss the downshift , relax and let the r's fall off and try again slower don't go over the top of your shift range to much. Just think of gears as a stair way. The flat part of each step where you put your boot is your acceleration or deaceleration. Top of 2nd equals low end of 3rd , top of 3rd equals low end of 4th and so on....... Hope this helps

 

I dont think i could have said it any better

I will add though...... the more you do it, the more you'll get better at it

 

I guess much like in a car if you listen to the engine and find the "sweet spot" you can slide out of / into gears without clutch? I used to entertain myself playing with that when I was driving my manual shift cars. On the Harley I only use the clutch on first gear, but I guess that goes for just about everyone out there.

 

yes but remember in a car you have a synchro mesh tranny. in a big truck you have straight cut gears which require you to float shift ( no clutch) or to double clutch. i also call float shifting rhythm shifting clutchless. the synchro mesh matches the gear and engine speeds for you ...

 

Thank you for the "education" on that as I didn't know modern trucks didn't have synchro gearbox. I know older trucks need the "double clutch" bacause my dad taught me how to drive on trucks and one of my first experiences driving on "my own" was on a Mercedes Benz 911 that needed double "pump" the clutch or those gears would scream like hell. Funny sometimes I would find myself double clutching on vehicles that didn't needed it...

 

lol, my pickup at work is an automatic , and every time i get in it i am trying to push in the clutch same when i come up to a stop sign...