Big Tranny
 

Can you down shift an 18 speed, the same way you can a regular
9 speed? Or do you have to split the gears down shifting, the same
way you would going up?

Yes, it will shift just like a nine speed. I don't think very many people split the lower gears anyway. Most use it like a 13 speed.

Big Tranny
 

So it is possible to downshift without splitting all the gears on the high
side?

if you have a heavy load i'd split em all going down but with a Light load or DH'ing I wouldn't split. Depends on the Terrain you're on too.

Big Tranny
 

Thanks guys, appreciate the info. :D

Newbie question: What is splitting the gears? :?:

Have you ever driven a truck with a two speed rear axle? Where you shift first gear low, first gear high, second gear low, second gear high and so on.

An 18 speed is going to work similar.
There is a stick shift with 4 gears, plus reverse and low. Each of those gears can be "split" with a switch on the gearshift. This switch gives you a "low (direct)" and a "high (overdrive)" for each gear.
So when you are loaded heavily and starting uphill you could shift like this: First low, first high, second low, second high, third low, third high, fourth low, fourth high.
At this point there is the range shift button to deal with. Shift that up before moving the stick again. Now you are going to start over again in the first gear low (now fifth low) and go through the motions again.

If that didn't help perhaps the picture from roadranger.com will:
http://www.roadranger.com/ecm/groups...uper18shif.jpg

The reason that there are so many gears is that the power/torque band of a diesel engine is quite narrow and fully loaded you may require every bit of that power to keep the load moving.

Thanks. I think so I know what you're talking about now. :)