10 speed to 18 speed

Drive it like a 9 speed; ignore the splitter.

As far as what RPMs to shift, ask the guy giving you the road test what RPMs he usually shifts at. If that truck is spec'ed for heavy haul, and if you're empty, you might be able to get away with shifting at or below 1500.

And good luck!

 

All I know is my 18spd is at 1,450 rpm's at 70mph.. Don't overthink things, just get in and drive..Eventually, hopefully quickly your ears will tell you when to shift.. It really isn't rocket science.

 

Like you, I knew how to shift a 10 speed, but not an 18 spd.
The way I learned to shift an 18 spd, was with me going on a test ride with my prospective boss. He showed me how to shift the gears, and he wanted me to start out in 1st and hit every gear, for a total of 16 gears. As an 18 speed actually has 16 forward gears, in the “H” pattern.

There are two buttons on the stick, the usual range selector on the front, and then the splitter button on the side.

When you move the splitter button, the trans up shifts when you let up on the throttle......so it doesn’t matter if your rpms are at 1500 or 1750 when you shift.

The split shifting keeps the engine in the power range better than a 10 speed does, so you typically are up shifting at the same rpm you would with a 10 speed. The engine rpms won’t drop as low when splitting gears.

The mph to gear formula won’t work out because you are splitting 8 gears vs the straight ten speed. Just observe your mph when you are in the high side of each gear, and write it down so you have a reference.

 

Gears on the main box are roughly a 400rpm drop. Splitter makes it a 200rpm drop. Ignore the splitter til you need it. Most likely you will only need to split the top 4 or if you are light only the top gear.

 

I always start in 2 gear and I believe its 3 or 400 rpm between 1234 then you go to the high range it is double the rpms so 6-800 rpms from 5678th gear but if you use the high low for each gear it is half of those rpms but when I'm driving unless in big hills or heavy go 2345 then when you get to 6th gear start using the H L for each gear and if you ever drove a 13 speed it's the exact same shifting on normal loads

 

Every other truck Ive driven except Freightliner puts a green operating range on the tachometer. The idea is to keep RPMs in the green. That really helped me so much when I started in my first truck, Peterbilt.

My last 2 Freightliners have nothing like that on the tach.

 

At CR England we were told that a truck was to be shifted when you reached 1800 rpm and the engine under load should not be lower than 1300 rpm. They figured this was best for efficiency. Your cruising speed should bbe at or near 1500 rpm (detroit engines). Yet these numbers wont mean squat on a cat / cummins motors. Each motor has a different band width for the power.

 

I don't have a clue what RPM I shift at. I go by sound and feel. I realized this when someone asked me to explain how to shift. The best I could come up with is telling them to keep it so smooth that a passenger thinks it’s an automatic. I think many drivers have problems explaining how to shift because at a cretin point it just becomes mussel memory.