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Old 12-07-2015, 08:08 PM   #1
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Increasing fuel economy-Gear Vendor

I would like to increase the fuel economy of my 1986 Vogue 2, that has a 454, TH400 auto and a 4.88 rear end. Short of replacing the motor what would and Gear Vendor OD unit do for millage? Over all getting around and up hills would this type unit help? Thanks Philip

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Old 12-07-2015, 08:10 PM   #2
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We added a GV OD unit to our '88 Okanagan 17' Type B MH with 460 and TT towing package. Made cruising much more pleasant but we never did get up to or over 10 mpg even so. In fact I would hazard to say that there was no increase in mileage, just quieter running.

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Old 12-07-2015, 09:40 PM   #3
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Mine came from the factory with gear vendors overdrive. I really like it and always use it. I can't say for sure if it saves money, but it reduces rpm at cruise by about 500, which I assume is saving some fuel. I hear they're pretty pricey to purchase and have installed. It would take a long time to recoup the investment.
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Old 12-08-2015, 07:05 AM   #4
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Based on my experience with vintage vehicles that have the 3 speed transmissions, the Gear Vendor does lower the RPM's and makes the drive a much more pleasant experience since the vehicle isn't screaming down the road but does little for MPG's. The price of those gear splitters are high and you most likely will not recoup the costs. Most folks do it for the better driving experience vs. fuel savings.
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Old 12-08-2015, 07:26 AM   #5
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I looked at gear vendor site many years ago on the first page it said if you are looking for better mpg SLOW DOWN I guess that guy got fired I see it no longer posted.
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Old 12-08-2015, 07:29 AM   #6
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Getoutdigin, we had a 1985 Country Coach 35 ft 454 w/tag axle. Had the gear splitter added for the reasons you state and did absolutely nothing for fuel mileage. The best money we spent was to have Doug Thorley headers installed. They are really thick tubed headers, not the cheap kind like kids put on their street cars. The stock 454 exhaust manifold from that era was very flow restrictive. That added performance and I'm sure helped the fuel economy some as well. Never could get over 6ish mpg., but at least the engine was breathing better.
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Old 12-08-2015, 07:39 AM   #7
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Increasing fuel economy-Gear Vendor

I would rather upgrade the transmission to a newer model, with 4 or more forward gears, than install an overdrive gearbox. For a vehicle of this vintage, the transmission (with no electronic communication with the engine ECU) should be a simple swap.

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Old 12-12-2015, 10:18 AM   #8
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Years ago I worked for a school bus contractor. In the fleet at that time the bus that got the best fuel economy was a 78 passenger class D unit that had a 250 hp DT466 navistar engine. Think it was around 7.6 average. The worst unit was a 35 passenger unit class C unit also DT466 but only rated at 180 hp. Think it was around 7.0. I do not recall what the rear end ratios were as this was 20 years ago. When you think about it your pushing a big barn door through the air which is what we also are doing with our RV's. I think the big difference between those 2 buses was the fact you could back out of the throttle a little sooner with the increased hp. I would guess the weight to hp ratio was better in the larger bus. Not been around one but I would venture the new RV units with all the electronics are not getting much better fuel economy than the 76 Dodge 440 that I am driving which runs right at 7. I know the new buses still get in the same mileage range and they have all the latest in electronics. It has more to due with frontal area that we have to push over length or weight. Talk to anyone that drives a class 8 truck. They don't change that much from empty to full load either because they still have to push the same amount of frontal area through the air. With the trucks if they can pick up a few tenths of a mile per gallon with all the skirting etc that they can add it will pay back over the life of the unit. But how many of use are going to put 750k to 1 mill miles on our RV before we move to a new one? I hate paying for the fuel too but I think the amount of money spent doing transmission swaps or gear upgrades is just as well spent at the pump. I find that if I keep the speed at around 50 mph that my fuel economy is slightly better. Best of luck to you no matter what route you go.
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Old 12-13-2015, 07:59 AM   #9
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I looked into this same thing when I had my P30 MH and found that to get the most for my money, I need to change the transmission. I was told to get a transmission that had an overdrive and a locking torque converter, in the end it was not worth the cost.
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Old 12-13-2015, 08:13 AM   #10
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I put a US Gear overdrive on a 1983 P30 with a 454 engine in the early 90's.
At the same time had a Banks header exhaust system put on.

Next day I went on a 2 week trip out West. Gain in MPG was 0.
It did help some splitting the gears on 6% hills.

I wouldn't do it again. Money spent would been better used to buy gas for that no better then 6 MPG MH.
Traded it off for a DP that gets 10 + MPG. And much better at climbing 6% hills.
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Old 12-15-2015, 07:51 AM   #11
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Larger hp engine will get better mpg when larger hp is needed.

Past life the service trucks would have the 302 as smaller engine should be better on gas...The 351 got far better mpg and fewer troubles as well as it was not working as hard.

Focus on things that net more torque or power from the engine as these will allow it to work better at much better cost.

Simple things like a slightly smaller diameter tire could help just a bit as long as it is still proper capacity.

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