does anyone have info on GearMasters Under/Overdri

Discussion in 'General RVing' started by tlary, Oct 2, 2002.

  1. tlary

    tlary New Member

    I am considering installing an GearMaster UNDER/OVERDRIVE on my F350 PowerStroke with a 6 Speed Stick, and was wondering if anyone has any experince with this unit. What type of fuel Mileage improvements can be expected. Any comments or recomendations would be appreciated. Considering the rather expensive price of this unit, it would seem that the payback on this unit would be rather lengthy. I don't tow my trailer (an 39' King of the Road) that much, but when I do it is usually in the NC Mountains. I have found the gap between 2nd and 3rd to be too much and thought that the underdrive feature would be very beneficial as well.
     
  2. C Nash

    C Nash Senior Member

    does anyone have info on GearMasters Under/Overdri

    Hi tlary, if you don't tow much I don't think I would go to the expense of the under/overdrive. It would take a lot of miles, if it ever did, to overcome the expense of the unit. Have a friend that had one installed on a gas burner and he was not satisfied. Might have better luck changing rear axle ratio and should be a lot cheaper (just a thought). Never had any personel experence with the units (AJMO)
     
  3. Butch

    Butch New Member

    does anyone have info on GearMasters Under/Overdri

    While I have never heard of a "GearMasters" unit, I have used a couple of other brands, one out of business but was identical to the GearVendors unit and it was fantastic. I also dropped the gear ratio from a 4.56 to a 4.88. This was on a 1974 unit with a Dodge chassis. The MPG went from 5 to about 8.3. In my "opinion", It more than paid for itself in performance while towing some pretty heavy boats up some pretty steep hills. U.S. Gear is another brand though it is a manual type where the GearVendors is electric / automatic. I would do it again under the same circumstances... I believe I paid $860 for the unit in 1974. Good luck. :)
     
  4. tlary

    tlary New Member

    does anyone have info on GearMasters Under/Overdri

    Thanks for the informati0n Butch. :)
    I had not found U.S.Gear and it sounds like the option that I should take. I have drive commercial trucks with two speed axels and was looking to see if that was an option for me. As I mentioned in my post, I drive 99% of the time with an unloaded truck. But when I need the diesel and the log gear, I really need it. The 4:10 gear means that I am turning about 3200 RPM at 65 MPH, which is where I spend most of my drive time. If I could cut that 20% then it only makes sense that I could save fuel and extend engine life. The 20% overdrive would give me about the same final drive ration as a 3.73 axle (whcih CNash recommended), but I can't tolerate the 3.73 axle trying to pull 16,000 lbs. up the mountains. I have plents of power for towing with my current configuration, I am just looking for something that gives me a better option for when I am not towing.

    Todd Lary
    F350 PowerStroke 6 Speed
    2002 King of the Road, Crown Royal
     
  5. C Nash

    C Nash Senior Member

    does anyone have info on GearMasters Under/Overdri

    Sorry Todd, miss understood your post :blackeye: . I thought you needed the extra between 2nd and 3rd while towing and yes,the over probably would help while not towing :approve: I would not recommend a 3.73 axle ratio for towing 16,000lbs.
     
  6. Larry

    Larry New Member

    does anyone have info on GearMasters Under/Overdri

    Todd,

    I have a Gear Vendors under/overdrive in a motorhome behind a TH 475 GM 3-speed automatic. This unit is 2speed auxillary transmission with a 1:1 direct and an 18% overdrive. I don't know where they get the underdrive part!

    I chose the Gear Vendors over the US Gear unit because I had 2 'must have' requirements. I wanted the overdrive for cruise and I also wanted a gear splitter to increase the gear selections. Both US gear and Gear Vendors provided both musts but the Gear Vendors provides the ability to shift between 'direct' and 'over' at full throttle while the US Gear requires 'lift throttle' to shift.

    Gear Vendors costs a little more but delivers a little more. I wouldn't be without it with my three speed. In your case, I don't think either unit will provide a small enough gear step to be a gear splitter on your 6 speed. All you will get is the overdrive. I would probably then choose the US GEAR.

    Larry
     

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