Direct drive OR lower RPM

10 speed vs 13/18 speed will effect resale value. Probably same mpg if u stay in direct drive. 18 speed has more flexibility. If you have something dedicated now and it changes it may be beneficial later. Depends on your situation. Do new engines give full boost from the turbo at that low of rpm? What's it like when cruise is on at 1100 rpm and you begin going up a hill?

 

sounds like someone has been listening to Kevin Rutherford too much. He also thinks you should haul freight at 40 cents a mile instead of dead-heading. That was I found out that he is nothing but a bag of HOT AIR!!!!!

 

Here is a Cummins Powerspec readout of a ISX15 450 1450/1650 Smart torque with a 10 speed direct

 

I did called Cummins, I talked to the district manager, and they do not have the answer. He said probably the same in fuel.

Ha ! what a joke! You called the DM and at a minimum he couldn't hook you up with someone who does know? Time for someone to get off their arse and get out of the cushy office.

He's supposed to be an engineer ! Should have a BsME or higher and should be a member of the S.A.E. along with other trade groups......

Sorry for the rant, my dad retired from Cat as a senior engineer. This is part of what he did, got and gave spec answers to prospective buyers and if
he didn't know then he knew where to find out. You got your answer even if you didn't like what it was.

" Probably the same in fuel" jeeze, get off your arse and open the books dude...... ( not you, the cummins guy )

 

Here is a Cummins Powerspec readout of a ISX15 450 1450/1650 Smart torque with a 10 speed direct



From a salesman! But the DM can't help....... he dunno....... sheeeet...... salesman does, janitor probably does too.

 

What is the downside to going with the 18spd? I don't see why you won't go with it when spec'in a new tractor. You can run direct all day in 16th or if time needs to be made up you can let her get into full stride. At the least you can play around with single over and compare with your fuel miles in direct. I understand that everyone has an opinion and their way is the best. But it sounds like someone has your ear and you have your mind made up on a 10 speeder. I get that your prolly not dumping alot of money into extras for your ride. You didn't say which kind of tractor your going with. But weather it's a Volvo or freightliner it doesn't matter. Spend the extra money on the 18 so you can experiment for your own which way works best for you. Good luck hope everything works out.

 

The advantage of the 18 with tall rears is flexibility, flexibility, flexibility. You have enough gears to address virtually every situation, and can run in direct at normal road speed for max efficiency. Even with tall rears, I find I hardly split the bottom end (just like a 13) except in rare situations. And the 18 allows me to stay well inside the optimum engine rpm's all the time. No need to rap the engine on the ceiling or lug it down too low. Having a 250 rpm band to work with all the time maximizes efficiency. And for down and dirty grunt, the low gear does just fine in hard starts, even with tall rears. I regularly get new trailers with those new air release slider pins. Trying to move those tandems with 46K lb in the box, especially on a newer trailer with all that anti-corrosion junk applied to the underside, from a dead stop can be somewhat of a challenge for any typical OTR truck. My setup handles it just fine. And for those rare instances that one needs to "put a wiggle in it" and get moving, like when running light load or bobtailing, just move that 18 into overdrive and cruise along at a nice clip and keep that engine down into lower rpm's.

Now, some might think that having so many gears is overkill. Not sure about that. In most every other transmission and rear end combination, no one uses each and every gear all the time. Same is true for an 18. But there is no other transmission being marketed that will handle extremes in torque and offer the most flexibility of the 18. True, with an 18 and tall rears, you wouldn't really use the overdrives, but with a standard rear ratio and the same tranny, you would be using less of the low gears often. It is a wash. If it is all about just using each and every gear all the time, then you need to find an old 6 or 8 speed direct and rebuild it. Good luck with that one.

Resale was hardly on my mind when I did this, as I plan on keeping the truck for a long, long time. But an 18 will offer better resale on the back end. Ask any sales guy.