Sprinter final drive ratio

LDB · Jul 22, 2012

I've done some searching but can't find this anywhere. On the Sprinter website in the build yours section they offer optional ratios of 4.18 and 3.92 but I can't find the standard ration listed anywhere. Obviously the 3.92 is going to turn lower rpm's than the 4.18. In theory it will get better fuel mileage although too low an rpm will hurt mpg's. Anyway, does anyone know the standard axle ratio? Does anyone know which of the 3 ratios gives the best mpg (presuming there must be a third or why would they offer two as extra cost options)?

Moot · Jul 22, 2012

Just a very uneducated guess; but from what you posted the 4:18 could be the low optional axle ratio and the 3.92 the high optional ratio, leaving the standard axle ratio somewhere between the two.

Steady Eddie · Jul 22, 2012

LDB said:
I've done some searching but can't find this anywhere. On the Sprinter website in the build yours section they offer optional ratios of 4.18 and 3.92 but I can't find the standard ration listed anywhere. Obviously the 3.92 is going to turn lower rpm's than the 4.18. In theory it will get better fuel mileage although too low an rpm will hurt mpg's. Anyway, does anyone know the standard axle ratio? Does anyone know which of the 3 ratios gives the best mpg (presuming there must be a third or why would they offer two as extra cost options)?

There may be 3- 4.18, 4.10 and 3.92. I have the 3.92, the 4.18 may be in the 3500. In 07 a lot came out with the 4.10 and hurt the fuel mile. In the 04 to 06 standard was 3.92.

GandJ · Jul 22, 2012

Here is some information that may help. RPMs and ratios

LDB · Jul 23, 2012

Thanks, that's interesting. After more research it appears there are only two ratios after all. I'd think the 3.92 would be best for mpg. It certainly doesn't have the engine lugging at highway speeds and I'd think would give better mpg.

From looking at that chart it appears a 3.73 might even be a better choice. That should give around 1750 rpm at 50 and 2500 at 70. I wonder why they don't want lower rpm at highway speeds?

Turtle · Jul 23, 2012

It has to do with both the EGR valve and the DPF. Both need a certain heat and pressure to work effectively and efficiently.

OntarioVanMan · Jul 23, 2012

Turtle said:
It has to do with both the EGR valve and the DPF. Both need a certain heat and pressure to work effectively and efficiently.

These days everything is connected to something....it is, what it is for a specific reason...
many years ago I ran into a fellow with an 06 sprinter and he had flashed his ECM to open it up....he said he could now do 100 mph.....I wonder how he has made out?....

LDB · Jul 23, 2012

Turtle said:
It has to do with both the EGR valve and the DPF. Both need a certain heat and pressure to work effectively and efficiently.

I don't doubt it in the least although it looks like it could have been designed to work with even more fuel efficient gearing but maybe not. In any event, it appears the 3.92 would be the better choice between the two unless one knew they were going to run at max gvw daily over Jellico or out west somewhere and then the 4.18 might be better.

LDB · Jul 23, 2012

Interestingly, although nothing to do with gearing, the turning diameter of the 144" wheelbase model is either 45.2 feet or 47.6 feet depending on which part of the website you check. Either one is a big improvement over the lwb GM product. The low roof model with gearing for around 30mpg isn't sounding too bad.

scottm4211 · Jul 23, 2012

Two things Leo:

1. The 30 mpg for the low roof is pre '07 models.

2. You seem obsessed with turning diameter.

xiggi · Jul 23, 2012

Leo i get more loads because of height than length. I would not go low roof.

As many loads might be more accurate i do three skid pretty often.

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Moot · Jul 23, 2012

LDB said:
Interestingly, although nothing to do with gearing, the turning diameter of the 144" wheelbase model is either 45.2 feet or 47.6 feet depending on which part of the website you check. Either one is a big improvement over the lwb GM product. The low roof model with gearing for around 30mpg isn't sounding too bad.

The long wheelbase GM is 155". The extra 11" will add to the turning diameter of the GM which is 54.5". It's a math and physics thing! Personally, the slightly larger turning diameter is a very minor issue when compared to the load weight distribution, smoother ride and overall vehicle stability that comes with the long wheelbase.

Turtle · Jul 23, 2012

LDB said:
I don't doubt it in the least although it looks like it could have been designed to work with even more fuel efficient gearing but maybe not. In any event, it appears the 3.92 would be the better choice between the two unless one knew they were going to run at max gvw daily over Jellico or out west somewhere and then the 4.18 might be better.

As with any diesel engine, you don't want to lug the Sprinter. Doing so is even less fuel efficient than the wrong gear ratio. For a Sprinter you want it to be at least 2000 RPMs in order for it to be efficient. Oftentimes in city traffic, including going through small towns, it requires manually downshifting to 4th or 3rd gear to travel at 30-35 MPH while keeping the RPMs up above 1500 to 2000.

Same as with xiggi, I get more loads because of height than length, especially since my available length is 9 feet instead of 12. If you do little automotive freight it won't matter as much, but all those automotive racks are taller than 48 inches. Many are 54, a few are 56.

jaminjim · Jul 23, 2012

Not trying to be funny but why would anyone be concerned with a CV's turning radius?

xiggi · Jul 23, 2012

jaminjim said:
Not trying to be funny but why would anyone be concerned with a CV's turning radius?

Because we like to do doubts in walmart parking lots when we get bored.

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zorry · Jul 23, 2012

Doughnuts.

xiggi · Jul 23, 2012

zorry said:
Doughnuts.

What he said.

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zorry · Jul 23, 2012

There probably have been nights where you've had your doubts. They could have been in a Walmart parking lot.

LDB · Jul 23, 2012

With FedEx if you are less than a dock high C unit you are all the same no matter what you actually are and they will load a maximum of 2 at 48x48x48. Rumor has it that will change in a year or so when a new system is put in place and they go by actual dimensions.

I know you don't want to lug any diesel but I'd think you wouldn't want to spin it too fast either. Looking at the 3.92 in the chart it appears that at typical highway speeds it turns 2200-2800. Going down one step to 3.73 would give somewhere around 2075-2675 at the same speeds. And as you guys say one could downshift as needed to stay in an acceptable rpm range. It just seems to me that if one's maximum speed is usually 70 or so it would be nice if it was turning 2222rpm or 2323rpm instead of 2626rpm and would save some fuel that way.

I'm not obsessed with turning radius but the tighter the better. There are times it would be helpful.