Manual transmissions

Just by looking in the cab you should be able to tell what transmission is in the truck. If its automated or Allison, no stick on the floor and no clutch pedal. If it is a manual, then its more difficult… or is it?

Original equipment shift knobs provide a huge clue. 10-speed transmissions only have a black range selector on the forward side of the knob. 13-speed transmissions have the exact same range selector, as well as a red splitter lever on the LH side of the knob. 18-speeds are similar to the 13, except the splitter on the side is gray. These observations are on Eaton transmissions. If there is some variation just note that a splitter valve on LH side means the transmission has 13+ gears. 

All of the transmissions can be shifted like the 10-speed, it’s the splitter that adds the extra levels of gearing. And using that spilt is totally optional. Below is the detail of each.

10-speed (400 rpm split)

• 400 rpm split

• Shift the pattern once

• Change range

• Restart shift pattern 

13-speed (400 rpm split in gears 1-5)

• Shift the pattern once

• Change range

• Restart shift pattern 

• Split gears in the upper range to arrive at 200 rpm splits, or shift w/o using splitter for 400 rpm splits

18-speed (200 rpm split capability in all gears)

• Shift to the 1st gear

• Split gear to arrive at 200 rpm splits

• Shift/split pattern

• Change range

• Restart shift pattern 

• Split gears as desired, or shift w/o using splitter for 400 rpm splits

So why are there different RPM splits? Think about it this way. If fuel economy is your primary objective, then keeping closer to the OE defined operating rpm range (the sweet spot) will conserve fuel. More rpm change equals a wider swing when changing gears. These 13 & 18-speed transmissions provide flexibility. Then there is always resale value, its commonly higher with one of these transmissions, again, based upon flexibility.