I haven't gotten one yet, but the thought has crossed my mind more than once lately. I'm not interested in the Sprinter-based RV's. They just don't fit my current style for camping. In my view a gear vendor unit would make a great option to be offered by the manufacturer so you could spread the cost out longer for those of us who would find it convenient to make it part of the payment. For me it would be more convenient than finding a mechanic I could trust to add the unit. Either way, I think it is a great idea. Maybe you could gain a mile or two to each gallon.
2001,Dodge 3500,SLT+, HO Turbodiesel, 6-speed, 4:10,Breman running boards, Rhino liner
1999 Travel Supreme, 33RLTSO
Good Sam Life Member
There's a feller on here...jimaugustin?..has done all of that. Knows his stuff so hopefully he'll be along. If you do a search here you'll find lots of answers. To your question tho...his experience was a good one...the bottom line tho is that there no appreciative improvement in fuel economy.
Last time this came up I remember the outcome being about what Gary says. You can improve performance but probably not MPG. At least not if your transmission is already an overdrive type. Our old Class C has a 3-speed auto and I have no doubt it would benefit in fuel use, but I also couldn't ever recover the cost in MPG. Think of how the new OD transmissions kick out of OD or want to be in Haul Mode. That tells you a GV unit won't let you do "double overdrive" very much of the time if at all.
What a GV WILL do, and several have testified to this, is give you a helpful spread in the lower gears. Steep grade, wound out in second, bogging in third. Just go to Second-Over with the GV and fall comfortably in between. This example is based on a four-speed automatic OD like Ford before TorqShift came out.
The Gear Vendors Over/Underdrive is best used with a tow vehicle. In other words it's beneficial when the vehicle is operated alternately with light and heavy loads. Doesn't really apply with a motorhome.
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