Thoughts on 2014 Volvo vnl 670 Ishift d13 with 2.47 rears

Are you sure it's 2.47? Never heard of it being that low. I have 2.64 in my Volvo. D16 I shift run 1150 rpm at 65

 

You'll just need final drive ratio and tire size to determine rpm at a particular speed, IIRC.

A Volvo manual says it's 0.78 (for 12th) and 1 (for 11th).

Assuming 11R22.5 tires and 2.64 axle ratio, the Eaton Roadranger app says you will get 70.2 mph at 1200 rpm in 12th, and 68.5 mph for 1500 in 11th. So I'd assume, it would probably be 1100/1400 for 2.47. I don't know the exact math required to calculate it, but it's probably close.

 

Volvo sales could answer your question about it.

 

I don't understand the thinking behind tall rears making it sluggish in hills. The reduction just happens in the transmission instead. The final result is the same.

Volvo probably did it because they know their current setup with 2.64 and I shift is perfect for 65-70mph. They have said if they could just get drivers to slow down the efficiency would be even better. That's now how we roll, though. This is probably exactly the same but designed for 70-75mph cruising speed.

Volvo knows what it's doing. They build a very good, efficient truck. It's just not for me.

 

A 2.47 rear axle ratio with a direct drive transmission amounts to 1,370 rpm at 65 miles per hour. A 2.28 rear axle ratio equals 1,265 rpm at the same speed. The 105 less rpm between the two equates to an approximate 1.5% improvement in fuel efficiency. Quote from Volvo with 22.5 tires

 

I got about 1175 rpm at 70 mph.
That would be a D13 with the XE package. It's designed to run ultra low rpm at highway speeds. Runs VERY quiet.
They are spec'd for running pretty much on flat ground. If you are in the mountains all the time, it is not recommended as it is hard on u-joints from all the lugging and you can't stay in top gear very much. But if you're just running all over the place it would be okay.

 

We had 2.47s in our shakers dd15 455 6.5mpg avg. Newer ones had 2.64 and 505hp got a tad over 7 in the northeast