Spec'ing auto vs manual.

Didn't you spec out one like this ...last year? Hauling product off the farm upstate to the market? Sounds exceptionally familiar.

I'd think more motor and you could run lower ratio rears and still have the oomph for the hills.

 

Did you miss one the last time you counted? Most trucks I see have 18 wheels on the ground. Unless you run a super single somewhere, of course.

*chuckle*

 

####, I thought something was wrong.

 

Get the Allison. Remember, this is an ISL, it runs a higher RPM. The Allison can't be beat for power and fuel economy, it's so comfortable and smooth. I spend all day swearing at my DT-12 Detroit auto shift. I can barely get through green lights, pulling out into traffic is scary. The jake brake is a pain...Allison and forget it, never look back.

 

@fredrd



That would be cool to have. Saw this pic today and wow

 

I can get 6-6.5 mpg in a 475 C-15 pulling almost 100,000 lbs at 65 mph and 3.5-4 mpg in a 550 C-15 pulling 137,500 lbs.

You should be getting a fair bit more mpg's running a motor at almost half the power.

 

The Allison is a beast of a transmission, aside from the tendency to kick down to 4th when engine braking I really don't have much bad to say about it. In heavy traffic areas they will wipe the floor with every automated manual out there. Pulling a hill, they are capable of changing gears at full throttle, without losing much in the way of momentum. Starting on a grade is nothing. The downside is, they're expensive, they're heavy, and they don't get the best fuel mileage. We run Allison 4500's and Eaton Ultrashift 10spds in our CNG tractors (identical spec other than transmission) and the Eaton's are nearly 1 mpg better. Also, if spec'ing a truck with an Allison, I'd tend to go higher on the HP requirement, since there are only 6 forward speeds. They do shed speed quicker on a hill, when riding behind a lower-HP motor. I've never used their new 10-speed TC10, but I'd like a demo ride to see how it compares.

I've used them in oilfield work, behind a 450HP ISX in straight trucks that often exceeded 90K gross, on-road and off. I currently use them behind ISX12G CNG motors, strictly on-road, lightweight freight usually.