10-Speed Peterbilt 379 - Save Fuel with 13-Speed Upgrade?

not sure what a thirteen speen is, but ive driving a few thirteen speeds, a couple 15's and even some 18's

short answer is yes.....being able to split the gears keeps the engine RPM in the power band, avioding the lugging and over revving that is constant on 9 and 10's

 

In our area, most trucks run 18 speeds that gives you 300 RPM, between gears, a 13 gives you 500 RPM. the more gears you have the better able you are to keep the motor in the best RPM range for what you want. I am a mechanic, that drove years ago, longhaul, and have test drove thousands of trucks.
Ten speeds never made sense to me but are cheap and cheap and cheap and cheap. I would imagine that when you get to speed a ten would have less resistance, less gears moving around.
Just a thought!

 

Cheap is why anyone would buy a 10spd because weight isn't an issue. A 10spd rated for 1850tq weighs 592# according to the Roadranger website. A 13spd is 696# and an 18spd is 716#. I was pretty surprised when I first saw this, I kinda figured some guys got the 10's to also save weight.

 

Some are also getting 10 spds to have a direct drive in top gear and about 2.60 rear ends claiming that single and double overdrives are less fuel efficient.

 

10 speeds are junk in the mountains, and the states is full of trucks for sale with 10 speeds. I dont know how people can like them

 

not sure where your getting that at Fuller 13 and 18's have identical ratios in the high range of the trans.

 

my 379 has 10spd with 3.70 gear and 11r24.5 and rpms are 1600 at 75.
I want a 13 or 18 for heavy hauls just not sure which one yet
advice anyone?

 

The only real advantage the 18 has over the 13 is if your heavy off road. I'd feel safe to say most 18spd trucks on the road today never split the lower gears. A friend had one and only used them once and that was just to see how it drove. I'm permitted to 120,000 gross, I have all 13spd's on fast gears (3:36 on 24.5's). I have no problems starting on hills, I can walk faster than it will idle along in low gear. I would be happy with either a 13 or an 18 but if ordering a new truck I probably wouldn't pay much extra for the 18. Both the 13\18 can be bought with a higher torque rating than any stock engine available. I know there will be at least one guy claiming he always splits his lower gears, yea whatever sure you do. IMO either would be fine and a nice upgrade to a 10spd.