Congratulations on the new truck. Please let us know how it goes with the Gear Vendors overdrive. I'm going to call Spartan tomorrow and see when I can get one of his units.

 

Don't know if this has changed recently or not, but my 450 with 4.30s actually shifts at lower speeds than my 350 did. It actually stays about 1 mpg less than the 350 SRW with 3.73s until you go over 60mph and 200rpm.
If you are in 3rd at 40 then the GV will split that and give you a gear half way inbetween 3rd and 4th.
Now for the GearVendor.

First, cruising flat and level and hitting reset on the Lie-o-meter while at speed then cruising for 5-10 miles.

350 w/3.73s 69mph: 16.7mpg, 59mph: 17.5mpg
450 w/4.30s 69mph: 14.7mpg, 59mph: 16.5mpg
450 w/4.30s and GV 69mph: 18.8mpg, 59mph: 19.2mpg

Second, cruising for around 60mph for about 50 miles, some hills and stops.

350 w/3.73s: 15.1mpg
450 w/4.30s: 14.5mpg
450 w/4.30s and GV: 16.7mpg

 

66stang351
This is some good info.
Couple questions.
What was the cost of the GV installed and is there a different one used for the 450?
What was your tach at when you were doing 59mph? 69mph?
Thanks

 

$4500 installed, and no it isn't a different unit in the 450. There is an option for an external cooler and increased fluid capacity though.

I figure at current fuel prices it will take about 60,000 miles to pay for itself in fuel. There is the added benefit of running lower RPMs and therefore causing less wear on the engine/transmission.
In the 450, 59MPH with tranny in OD and GV in direct: 2000RPM...double OD: 1500. 69MPH 2250 and 1750 repectively. In the 350, 59 at 1750 and 69 at 2000. The 500RPM drop in double over is great.

I now have about a hundred miles since I hit reset on the lie-o-meter and with 90% 60MPH and 10% stop and go city driving it is at 16.4MPG. Without the GV I would be around 13.5MPG and with the 350 w/3.73s around 15.5MPG.

 

66stang351 Great to hear about the gear vendors. I plan on getting one later this year. Who installed yours? Was it a local company, or? Camper World said they would install it for $600, but don't think that includes doing the drive work. Keep us posted.

 

I had Camping world do it. And, no, the $600 does not include the driveline work. They quoted $150 for the driveline and then bumped it up to $300 before they were done. They send the driveline out to someone else to do, and I guess the '08s require more parts...different u-joints or something.

 

66stang351 Thanks for the info on mpg's and rpms. Any idea how much your truck weights?

Mine weighs in at between 12.5-13K with my tools. Best so far reseting at highway speed has been 10.3mpg and only for a short time. Wish I could see 15 even for a breif period.

Any idea on what you are getting hand calculated on average either with or without the GV unit? Have you tried throwing it in GV OD at low speed (25+) and just running on the faster gears around town? I'm wondering how the truck performs, OK or slugish? Does it seem to shift at about where it does with the GV unit off? My biggest concern is I seldom get to drive faster than 45-50 most times and lately the locals have lowered many areas to 35-40 and you are lucky to get people who will drive that.

Thanks again for all the info.

 

This is a very good string, and I'd like to offer a couple of comments.

<O</OI have an '08 F450 with the factory 33K CGWR package (includes 4.88's in the differentials). My mileage is similar to others - maybe 13.5 at 55 unloaded and less than 10 towing (depending upon the weight).

The truck is used on a farm, and routinely tows heavy trailers (up to CGWR and then some), loaded with tractors, hay, logs, lumber, etc. I've owned it for around 14 months.<O</O
<O</O

I am extremely interested in an overdrive unit (and have been since I purchased the truck), because reducing the engine RPM to 1,600 rpm or thereabouts should take my mileage up to 18 mpg or more (when running empty).<O</O
<O</O

Because of the weights that I routinely pull, a year ago I researched the GV unit, and spoke directly with one of their engineers. His recommendation to me, in no uncertain words, was DON'T USE A GV UNIT IF YOU TOW HEAVY LOADS. Although the factory rates them up to 30K lbs CGWR, he said that the units will not withstand that amount of loading on an extended basis w/o destroying themselves. He also stated that they did not have plans to introduce anything more substantial.

<O</OI also spoke with an engineer at US Gear, and he indicated that they did not have any plans to bring out a unit that would work with the F450 / 4WD Torqueflight transmission combination. That was a year ago though; they may have changed their plans in the interim...
<O</O

From my perspective, I would love to see a heavy duty overdrive unit that offered two OD ranges plus a one-to-one ratio. For my application with 4.88's, I would like a unit that offered choices of 1.3:1 and 1.6:1 overdrive ratios (in addition to 1:1). That would provide me with an engine RPM of approximately 1600 or 2,050 at 65mph (and be the equivalent of achieving the same RPM as either a 3.5 or 4.11 ratio rear end). I'd use the 1.6:1 ratio for running w/o a trailer, and the 1.3:1 ratio for towing an empty trailer. The 1.6:1 overdrive ratio should yield MPG's in the 18 - 19 range when unloaded at 65.

In addition to the F450, I have two GMC 5500 chassis trucks with Duramax's, an Excursion with a 6.0 PSD, and a Ford 9000 with a Cat diesel. Previously have owned two F350's with 4.11's and 6.0's, and a Chevy F350 with the older GM diesel and 4.10's. It sure would be nice to have some heavy duty OD units available...
<O</O

 

I'd LOVE to have one for use when I'm NOT towing, 95% of the time, but I'd hand grenade one for sure at 35,500 GCVW as seen here:

 

My thoughts on using the GV in your situation are that it won't do you much good. City driving will cause a lot of variation in speed and that is what will kill your mileage more than running high RPMs. To make it work for you , you would have to split gears manually with the GV as you are accelerating. You could also use it in situations where the torque shift won't shift and you are at a constant speed to lower RPMs. If you find yourself stuck running 2000+ RPM for any extended amounts of time then the GV will give you the extra gear you need to lower that. However, I would be willing to bet that most of the economy is taken away by acceleration and the benefit of the GV would be minimal and take a lot of work.

 

66stang351 - Ordered my Gear Vendor overdrive unit today. Camping World said it should be in within a week, then I will have to get it scheduled to have it installed. They said they would need the truck 1 1/2 days to get the shaft cut and everything installed and checked out. Will be happy when it's done. Will let you know how it goes.

 

Good luck mick...I had my install scheduled before my dealer even ordered my truck...

 

Any updates on the GV units? Good Bad? Let us know!

 

No problems at all. Still seeing a 2-4 MPG increase highway and about 1 MPG increase driving rural and city. I think the thing I like the best is the lower RPMs on the engine when cruising. When running 500RPM less for several hours at a time on the freeway, that is a lot of wear saved on the engine.

 

i have a 08 F550 crew cab 4x4 200"wb, with 4.88 gears. used to pull 38' toyhaller and 32' stacker race trailer all over playing/racing, had a baby so not much playing/racing/towing now, getting 9-10 mpg empty so really interested in this.