Gear Vendor

[Jack Wasmuth]

Any one have any experience with a Gear Vendor? Thinking about one for me 1976 Dodge 360 with TBI. I get 9.5-10 mpg now, hoping for more.

What are your thoughts?

[Jack Wasmuth]

I could change the rear end gears and get better fuel mileage.  With the Gear Vendor I can split gears and get about 20 % less rpm down the freeway.

I may have a problem with a taller rear end when I tow my car and go up some step grades so that is why I was thinking about the Gear Vendor.

[Lakota Wolf]

There are several manufacturers of a Gear Vendor unit. They have several models that fit onto the Back of the tranny, eliminating a carrier if you have one,, and a unit which is old school that mounts on the input shaft of the rear differential. Basically adding an additional gear,(think over drive gear). My Dodge Diesel had a 2 speed rear end, and all it was,,was an installed extra gear on the differential input,, leaving the original 4;10 axle ratio. Was great on the straight away having that *extra gear,, and can flip a switch on the shifter to drop it out of the *overdrive,per say for a steady incline... With an average rating of a 20% increase in economy,, if you keep the rig for a couple years, it actually pays for itself and it helps you keep up with the flow of traffic.

[Jack Wasmuth]

Do you know the name of the manufacturer?

[Lakota Wolf]

WWW.Drivetrain.com has some specs of their products, with newer and more efficient units.

My gear vendor unit was built by DANA corp..

[Lakota Wolf]

Pat is right, if you change the gear ratio to a higher gear ratio, you will end up LOADING up the engine, putting to much demand on it with low RPM's, resulting in you having to drop down a gear to get back into the power band to have the torque to pull. The only efficient method is adding an additional gear for a steady flat highway speed with lower RPM' without dropping so low as to load up the engine. Motor homes a.k.a.  3/4 and 1 ton chassis vehicles use the 4:10 / 4:11 gear ratio's. With the idea being that these heavy duty trucks usually cruise at or around 55 mph. Max.

[Jack Wasmuth]

I know that changing the gear ratio is not a good idea, I was looking at the idea of a two speed rear end but I think that I will stay with the gear vendor.

Thanks

[Rich Thomas]

Greetings Jack, A year or so ago I was in your position and was looking at adding an over drive unit to the Palace. I done some research but decided to leave well enough alone because of the cost and recovery; I didn't see it to be a good fit with my only using the Palace to travel around the state of Ohio and surrounding areas. I didn't think I could ever justify the cost.. Now for some one on the road a lot would be a different story. One option I found with Gear Vendors was a system that came in between transmission shifts.; tranny goes to first then GV comes on some where between first and second and so on. in essences making a four speed an eight speed. I didn't get way into this unit because it cost $2,700 or so according to the wright up I was reading. Then there is just the standard bolt on O.D. but you will still be paying out some green for that as well and for both you will have to replace the drive shaft. All the peripherals aren't cheep either. There is an other option you could toy with to some degree without re gearing or adding an OD unit and that is tire size. You can do this by comparing ratio's and doing the math without buying any thing. I know that when I went to my current tire ( 9.50 x 16.5) up from eight something. it made the Palace a lot better in ride quality and possibly even a little better on gas. I never have checked fuel millage on my Motor Home; if i did I would probably park it LOL. Any way you spin it, It's going to be expensive and you aren't really saving anything if you don't have a chance to recoup your investment. Your not saving anything if you don't at least do that.

[Jack Wasmuth]

Thanks Rich. That is the 64 thousand dollar question. How much will I use it to recoup my investment. Best laid plans of mice and man.

I do not believe that I would ever get my investment out of it but I may if I sell it. I have visions of keeping it for many years to come and I like to travel a lot.

I need to do a lot more thinking on the subject.

Thanks for your input. I value it greatly.

Jack

[Daniel Long]

I had a 1977 Dodge Tioga with a 360 and 3 speed. We got about 9-10 mpg and from all the folks I talked to that is the best you're getting unless some major weight and/or drag reduction is happening. That's actually not bad for a Class C that's 40 years old. I think that messing with it now will only reduce your mileage or any reasonable payback. I spent time updating stuff like the electrical generation, swapped to LED's everywhere and was planning solar until the LH1 bombed out in Florida. Now we have LH2 (Tiffin Allegro 1987) and am planning some new trips this year. Best of Luck.

[Jack Wasmuth]

Thank you Daniel. The more that I think about it the less that I want to do it. I have all of the power that I need and the mileage is good. I believe that it was a thought in passing and a little bit of boredom on my part. I have always had a saying "it it is not broken, don't fix it."

Jack 

[Ralph Javins]

Good morning, Jack; 

The Gear Vendor 3D0475 Over Drive bolt-onto-the-back of the 3L80 three speed automatic transmission is what I am working toward also.  The plan is to do the engine modifications first to make sure the engine can pull the 22% higher gearing on the level ground, and be able to drop back to standard 3rd for the grades and then 2nd-Over for the steeper climbs.  The calculations say that with this full package, I should be able to go up the West side of Steven's Pass in 2nd-Over at about 50 MPH or maybe 55 MPH instead of the 35-40 MPH that I can climb that hill now with the 15,000 pound weight that I normally run with the P37 motor home chassis. 

If the C-172 comes to an end this winter, and it is looking like it will, because I am not able to pay for the full MOH the O-300B engine is looking at right now, then completing the P37 engine-driveline conversion should be possible by this coming spring.  That will be nice. 

While there is hope for an improvement in fuel economy, my main goal is the use of the over-drive on 2nd and 3rd gears for climbing with 2nd, and hopefully flat land fuel economy with 3rd. 

One thing that I noticed is that I will need to recalibrate the speedometer, or somehow move the speed0meter-odometer cable off the transmission and back to the driveshaft where it will not change as gears are shifted.  One possible work-around I can do right now is to use the GPS box speed display for complying with the speed limits.  Besides, while the speedomoter is accurate, the odometer in my P37 is about 10% optimistic and makes it seem like the 454 in the P37 is getting much better fuel economy than it actually is.  Using the GPS box for a more accurate indication of actual miles traveled was disappointing when I first calculated the fuel economy that way.  It seems that the C-172 actually does get better mileage than the P37. 

Enjoy;  Ralph,   Latté Land, Washington