Help me build my first new truck as an owner operator!

I won't dispute that fact considering that I said with a 10 speed and not the 13 that you are referring to. The point is that you agree with me in the end about the efficiency of the setup. We spec our trucks with 2.65 rears, 10 direct, 22.5 lp's and we turn about the rpm that you are stating(65 mph at 1350).

 

What kind of fuel mileage are you getting with that setup? Any fuel system mods added on to the truck?

 

I drove a few T2's for a tanker outfit in Fl.

Most had a 475 Cat (3406B), Super10, stand-up sleeper, 3.90 rears (I think).
If I recall correctly, 70mph @ 1650rpm although memory might be failing me on this.

Best fuel mileage was aprox 5-5.2 w/79,900. Take this with a grain of salt because company reprog'd ECM with "their" idea of what constituted better mpg's. None of the other fleet T2's did any better than mine.

Bigger CAT(550 3406E) in same truck got almost 6mpg w/79,900. Same improvement in mpg over 3406B reported by other 3406E owners.

Interior noise was low most of the time.

Only time noise increased was in high headwinds or on a few bumps that vibrated the door top area around the door gasket. In hi headwinds, the tops of the doors around the door gasket seemed to flex momentarily. Seemed like they were being "pushed open".

Kind of odd I thought but didn't happen very often.

I had only one major problem with any of the Cat 475's. The motor would intermittantly & only momentarily loose power. Didn't matter the circumstances. Shotgunning a couple sensors fixed that. Also, the Jake wasn't worth a #### on this motor. Other 475's I drove weren't any better. Just changed the sound of the exhaust more than anything else.

After I reset the airbags to work correctly with the trailer & load, it was a great ridin' truck. I hardly noticed the bumps across La's I-10 & I-12. I-95 thru CT & NY were no problem. I heard other drivers talking on the cb's going thru these places & it sounded like they were ridin' a lumber truck or a bucking bronk. I more or less just eased thru there very comfortably. Never did feel what they were. And this was with a few dead shocks which the company wouldn't replace.

Storage was ok. Not the best compared to the other trucks I've driven. Good enough to stash a fairly large tv, a few days worth of canned & dry foods, a porta potty & mucho clothes. I would have liked a shelf across the rear bunk like my Mack had. I really would have liked to burn that closet out from behind the drivers seat. I like to slide the seat back & was forever hitting that damnable closet.

I drove a few T6's. Very nice truck. Rode very well once the suspension was set. Handled like a go-cart compared to the T2's. I liked the storage in the T6's slightly more than the T2.

Only thing about the T6's was the mufflers were in the way of the mirrors it seemed. With electric mirrors, not a big problem.

In comparing the T6's engine & drive train to the T2. The bulk of the T6's had Detroits & super 10's. I think they were pretty big Detroits but I don't recall what. Good pullin' motors though. Hardly had to drop a gear on a climb. The Jake actually worked on these. Very well as a matter of fact.

Now you know as little as I do.
bc

 

(gear ratios) Correct me if I'm wrong. If the number to the right is lower than the truck will have a higher top speed, and less torque. Also if the number to the right is higher it will pull well, not run as fast, and get worse fuel mileage! If I'm right 3.38 rears make a fast rear end, that's not preferable for pulling. And a 3.90 will pull like hell, but has a lower top speed @ high RPM

 

7.11 mpg fleet wide average on most recent fuel tax reports. Keep in mind that all the company trucks except one are governed at 65 mph, and also our average load weight on our outbound loads is about 18,000 pounds.

 

Yes, that is pretty much correct but once you drop the first gear when pulling you will essentially negate any advantage/disadvantage of the gear.

The thing that I want to make clear is that it is easy to make a misassumption when referring to a 2.65 rear gear. If you have a direct drive tranny ("direct" meaning a 1:1 final gear ratio), you have to have a gear like that to match up to the operable rpm range. Most conversations regarding rearends range from 3.36's to 3.90's because those are the operable gears for the much more common overdrive trannys.

The way that a person should select the gear they need is to first determine what speed they will most likely "cruise" at on the open highway. Once you decide what your speed will be, you then figure out the gear that will correspond with the rest of the pertinent specs(tire size,tranny) to allow the engine to be in the "sweet spot" when cruising at that speed. For example; my trucks are set at 65 mph so with the rest of our specs ,we use a 2.65 gear to put the truck at 65 mph at 1350 rpm or so. The sweet spot will be between 1325-1475 rpm depending on the motor.

If you just buy a truck with whatever gear ratio is in it and it doesn't match your driving habits, you just shot yourself in the foot big time. For example you buy a truck that is setup for 65 mph and then drive it 75 mph, you just raised rpm approximately 200 rpm or so and right out of the sweet spot and into the "drinking fuel" range.

 

Just get a freightliner with a detroit you will be fine for mpg...

 

If I were to decide on a 470 Detroit with a 13 speed, what gear ratio and tire size would you suggest if I cruise at 70 MPH?

 

Can you set up you ECM to tach your motor out at different limits on every shift? Say limit all the gears to top out at say, 1700 RPM's and have your top 1 or 2 gears tach out at 2100?