What's with all the gears ?

10 speeds are the most common with fleets because they are tough transmissions they get the job done and they are easier to teach rookies how to drive them without doing damage to the trans.

the more gears the closer your rpms between each gear to allow you to run the engine more optimally, witch is especially important when over 80k but even usefully at lighter weights, 18's are basically a stronger 13 that allows you to split the bottom side as well as the top witch is most use full in trucks that are used for real heavy haul or that spend time off road.

15 is basicly a cross between a 10 speed and a 18, 10 speed pattern that allows half gears on the bottom side. usefull for getting heavy loads rolling or offroad

9 speed is essentially a 10 speed but with a 13-18 speed shift pattern without any 1/2 gears.

13 is a 9 speed that has 1/2 gears on the topside of the box

 

its all a package deal what engine your running with what trans with rear ends to match for the type of freight your hauling.

a guy running permitted loads at 180k gross is going to spec a truck a lot different than a guy hauling auto parts in a dry van at 65k gross.

the whole drive train works as a package what is optimum for one application wont be for another but everything works together to achieve what you want what motor coupled with what trans and what rear ends.

in my opinion you can never have too many gears in your trans, you don't have to use them all if you don't need them but you have them available if you do. but a 13 or a 18 can be a bit much for a new driver to get the hang of, so if you had a truck that you were going to put new drivers in you would probably choose a 9-10 speed for ease of use and less transmission repairs resulting from driver error

 

nice thing about the 18 speed is you can leave it in OD and run it like a 9.

i hate 10 speeds. i like the 9 speed platform.

 

Plus the 10 speeds aren't rated for 550/600hp with 1850/2050 lbs of torque. You need a 13 or 18 speed.......

Also with a heavy load and high hp it's nice to split a gear and go. A lot of times this will put you over the top of the hill. After a while you just know when to split and when to drop a full gear......

 

If you're doing anything in off-highway conditions, 18 speed is the way to go. For a highway truck, it can allow you lower rear end gear ratios and additional gears on the low side to compensate.

 

There is only one thing worse then a 10 speed and that is a super 10. If any one has operated one of these I'm sure they will share the same opinion. Had a super 10 in the flat top freight when I was running flatbed. The Detroit 60 worked great but so many times I wished for more gears. I have always been a 13 speed fan always thought they were stronger then a 18 but could be wrong.

 

All motors have a sweet spot on the RPM range. The closer you keep it to that spot, the more power and mpg you get. In a 10 speed truck you may need to drop 400-500 rpms on each shift since the gaps between gears is pretty big. On a 13 0r 18, the gaps are smaller thus you can stay closer to the peek rpm. On real heavy or hilly conditions the extra gears help since the rpm drop will be ore under these conditions. On flat driving with not real heavy loads a 10 is just fine.

9 and 10s are similar except a dfferent shift patern. A 13 is a 9 that has splitable top gears. (half gears) A 18 is a 9 with all gears splitable.

 

Just because you can split the gears, you do not have to (I think). Could you teach someone to drive an 18 speed but drive it as a 9 speed? As they get more comfortable then they would start splitting the top end. since you are not splitting, would that cause any damage to the tranny?