Thoughts on 2014 Volvo vnl 670 Ishift d13 with 2.47 rears

I getting 7.2 mpg in 2012 volvo 670 10 speed with D13... I will have to look at gear ratio next time I go in.

2.47 gear ratio seems super tall... I didn't know they went that high

 

They go as high as 2.28 now. Meritor, Detroit, all of them. It all comes down to what you are doing and where you are doing it at. For direct drive and what I do, the tallest I could even consider is 2.50 with the newer engines. 2.47 maybe. I ran both the iShift direct and the OD version thru my road speed calculator spread sheet, and settled in on 2.5 (essentially 2.47 asked about) for the direct drive and 3.21 for the OD as the tallest I could deal with doing what I do with a truck. My sheet looks at the top 6 gears of the trans and then you can compare side by side the RPM changes per shift and road speeds from 1200 thru 1600 RPM in 50 RPM increments. These spreads assume 22.5 low pro rubber. I run a lot of roads that I have to do around 60 mph or less on, and quite heavy sometimes, and even when I cruise on the big road, I typically only run about 62 mph. Just me. I haven't felt that need for speed. I guess all those years of national 55 speed limit set me in my ways. I can still run 65 or even 70 with these rear ratios when I need to and not have the D13 engine going outside the peak torque band. I run way too many hilly areas to play the down speeding game that Volvo wants to play. Running at 1100 RPM is not in my game wheel for efficient running with the heavier loads I pull and where I pull them. Even on Volvo's D13 spec sheets, they say to gear so that engine is running between 1200 and 1500, so forget the marketing nonsense.

With either, you have roughly a 350 RPM engine drop between shifts.

Here is the iShift OD version.....



And here is the Direct Drive version.....



Give me any ratio you want to check and the tire rotations per mile and I can post a spread shot of it.

 

3.08 with 18 speed double over and 11r22.5 rubber (Michelin energy)
Peas and tanks

 

Ok, got out the spread and plugged in 2.47......