Gear vendor, under overdrive for 727, Anyone have one

Transmission and Drivetrain Tech

  1. mistreta

    mistreta Well-Known Member

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    Thinking about a Gear vendor under, overdrive for my 727 in my 408 Duster. OK around town
    355 not a long haul gear. Sounds like a good upgrade.
     
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    • HemiDenny

      HemiDenny HDK Suspension FABO Gold Member

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      I have a GV on my aluminum case 4-speed....and one in the box for the 727 that is going in my next project. It will split shift like the dump truck I drove in my twenties, but I like it for anytime over 55mph.....especially on the 4-lane doing 65-70 @ 2200-2400 rpm.
       
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      • HemiMark

        HemiMark Well-Known Member

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        I may have to look into one for the dart
         
      • HemiMark

        HemiMark Well-Known Member

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        If I'm not mistaken there is a floor modification needed?
         
      • dodgedifferent2

        dodgedifferent2 Well-Known Member

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        I debated the gv behind my 4 speed but can't justify the cost. So I keep cruising with the 3.55's
         
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        • jbc426

          jbc426 Well-Known Member

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          The ratio of overdrive gear vendors provide is not really worth it. I drove a buddies 727 with gear vendors and was disappointed with the rpm drop when it was engaged.

          If you really want to enjoy your 408, swap in a built 200R4 with a high stall lock-up torque converter. It's like having a 5 speed automatic. The 200r4's first gear is .25 lower than a 727's, and the overdrive is .67 to 1.

          There's a night and day difference between the two ways to add overdrive to your old Mopar. If you drove your car with each set-up installed, you wouldn't ever consider the gear vendors.
           
        • DesertRat

          DesertRat Well-Known Member

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          I have a GV unit in my Barracuda. My combo is commando+ 273 build with late model 904 based transmission W/custom lockup converter. I had my 8 1/4 shurgrip built with 3:73 ratio and will be running 245-60R-15 on 6"stock rally wheels. I expect to be running about 2400 rpm at 70 mph.
          Don't know if that is good or bad but those are the cards I chose to play.
           
        • HemiDenny

          HemiDenny HDK Suspension FABO Gold Member

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          Just for discussion....the GV reduction is .78.....takes my 4:30s down to 3.35.
          How much lower do you need in a hot rod?

          I bought my second one second hand / but still in the box....delivered to my door for $1500. There are used ones out there if you want to save some bucks.
           
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          • mistreta

            mistreta Well-Known Member

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            Interesting, Thank you for your input. The 200R4, what is that used in, is it a bolt in replacement for a 727?
            I would like to know more.
             
          • limegreen70

            limegreen70 Pokorny Enterprise's

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            What size rear tires do you have?
             
          • abodyjoe

            abodyjoe Well-Known Member

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            have a few friends with them,... all of them love it.. will turn those 3.55 gears in to what? 2.76 i think.. awesome for the highway
             
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            • Treblig

              Treblig Well-Known Member

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              The 2004R is Gm overdrive automatic. I have one in my '69 Barracuda. I absolutely love it!! It requires an adapter plate sold by numerous companies. It is not a bolt in replacement. It also requires minor trimming of the upper trans cross member and changes in driveshaft length. The TV cable connects to the carb (adapter bracket so you won't need the Mopar linkages.
              I installed mine complete for about $1800, I did all the labor.

              Treblig
               
            • ir3333

              ir3333 Well-Known Member

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              408...hmmm,You should be able to boil the hides with 3.23's, which are a nice cruz gear.
              Maybe try a 3.23 gear first...you might be happy right there.I know that doesn't answer your question about a GV,just a thought
               
              Last edited: Dec 1, 2016
            • mistreta

              mistreta Well-Known Member

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              Rear tires are 255/60
               
            • HemiDenny

              HemiDenny HDK Suspension FABO Gold Member

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              just a fuzz shy of 30" tall
               
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              • jbc426

                jbc426 Well-Known Member

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                More than that for my tastes. Heck, even 3.23 are pretty wrung out at 70 mph with a 28" tall rear tire. With 3.91's a .67 overdrive knocks the revs down nicely to an effective 2.62's ratio, and a lock-up converter adds a nice rpm drop too.
                 
              • jbc426

                jbc426 Well-Known Member

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                Or you can use a bellhousing and adapter to bolt it to your motor. The car does need some modifications, but the floor pan remains the same. US Cartool makes a crossmember kit for them now.

                200R4 3 (Large).jpg

                Heart (Medium).png
                 
              • HemiDenny

                HemiDenny HDK Suspension FABO Gold Member

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                That is a great option too......especially for hyway use.
                 
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                • DesertRat

                  DesertRat Well-Known Member

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                  Don't forget you have to cut down the tunnel support structure and reinforce it. I considered that transmission but my car was cut and buffed and too far down the road for that option. That mod is best done before paint.
                   
                • jbc426

                  jbc426 Well-Known Member

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                  I'm a believer in reinforcing the car as much as possible unless it is some kind of numbers matching car for sure. I welded in US Cartool subframe connectors and their full chassis stiffening kit in addition to welding the torsion bar crossmember solidly to the floor, thinning it out in cross section and reinforcing it with my own fabrication.

                  The shock towers on the late 60's A-Bodies are just hanging in the air with a few spot welds at the top to hold them to the inner fenders. I welded mine solidly to the inner fenders from the frame rail up, and have the under fender bracing welded in too. It makes the car feel WAY more solid on the road.

                  I painted my floor and trunk with that roll on bed liner for durability under the carpet. If you are interested in painting the floor and undercarriage body color, you sure would have to do the modifications before paint. I'll spray them all body color once I finally get the exterior paint done.
                   
                • branded209

                  branded209 Well-Known Member

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                  Nope at most a little dent
                   
                • DesertRat

                  DesertRat Well-Known Member

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                  I now have mine installed and tested. I had to lower the transmission crossmember 1 inch to clear properly. But with 3:73-1 gears and 275/60/15 on 8" wheels I am at 2300 RPM at 70 mph-with a lockup converter. It runs well there and the control is fantastic.
                   
                • RogerCox

                  RogerCox Well-Known Member

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                  I also have a 408 stroker (465 hp) and was thinking of either running 323 gears or getting a Gearvendor and going 391’s.

                  going to be running a 295 tire, if I can brake traction easily with the 408 and the 323 I’ll just save the 3k, not doing to much high way driving.

                  What do y’all think?
                   
                • RogerCox

                  RogerCox Well-Known Member

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                  am adding Gerst front K member and 4 link in rear (Dana 60). Should I look at getting level 1/2 frame stiffeners? Will also have a 8 pt roll cage.
                   
                • famous bob

                  famous bob mopar misfit

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                  Hey , how could .78 reduction ,take some thing down to .95 REDUCTION ---------------------------??
                   
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