Best overdrive options?

1971 - 1974 Mopars

  1. KramerSwinger

    KramerSwinger Well-Known Member

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    So I have a 73 Charger. The car is being "built up" as a daily driver/cruiser. The original 400ci big block is currently being warmed over with an aluminum top end and Holley EFI. 325hp is the target.

    I know that the 73-74 had major shifts in the suspension/chassis dept. Anyway, I was wanting to, down the road, install a GearVendors unit. Better mpg, easier on the motor, so on. But recently I was speaking to a 74 owner who apparently looked into it and found that the GV is not a relatively easy install in these models. Crap!

    I've heard of the a518 swap, but that also requires serious trans tunnel mods that I'd like to steer clear of. I've also heard of some kind of 4l60e style transmission, but that seems risky as now I'd be mixing in Chevy stuff. Frankendodge seems foolish.

    So the stupid question of the day is this: Are there any other good options for an overdrive? Or must I cut into my floor for it?
     
  2. tmaleck

    tmaleck FBBO Gold Member FBBO Gold Member

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    First off, i have no connection with these guys. I am looking to to something like this for my 68. Silver State transmissions is big into the 4L60 into mopar stuff. They have a variety of kits including controllers. Kind of pricey, but may be worth looking at.
    Tim
     
    Last edited: Dec 22, 2017
  3. mmissile

    mmissile Well-Known Member

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    Nothing good, is easy. These old piles weren't designed for anything other than what they were built with. I'd probably go the easiest route, with your anticipated HP levels. With a solid build, I don't think you'll hurt any choice you go with. Good luck, and Merry Christmas.

    I'm finishing a GV setup, and have done a NAG1 in another. Neither was bolt-in...or cheap/easy.
     
  4. Dennis H

    Dennis H FBBO Gold Member FBBO Gold Member

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    69 Coronet here. The Tremec was put in about ten years ago. TKO 5. Keisler. Perfect gears for the freeway. 2150 @72 MPH w/3:54 Dana. It has always leaked. Everywhere. Google it. Also has 2-3 high rpm shift issue. 3rd is often missed as the gate jams between 3 and 5. Normal diving is no problem. If to do again, I would research Gear Vendors. Back then GV was thought of as a Chevy thing. Previous threads on this here too, so look around. Good luck.

    I just had a new rear seal put in the Tremec. Duralast from Autozone. Gonna steam clean underneath today. The trans fluid threw onto the driveshaft then the exhaust petty bad from the
    Los Angeles trip in October. Goddam mess. The newest component on the car leaks the most.
     
  5. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    mmmm as far I know these will fit on SB... No A500 or A518 trannies for BB, since they appeared long time after the BB was gone. Unless I'm missing something
     
    Last edited: Dec 16, 2017
  6. Dennis H

    Dennis H FBBO Gold Member FBBO Gold Member

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    Also, an A855 Passon may be available. Orders are running 4 years. Break in is tedious.
    Search prior threads on this as well.
     
  7. 451Mopar

    451Mopar Well-Known Member

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    Not so much the trans tunnel as the part of the T-bar support the runs inside the trans tunnel makes the tunnel really narrow at the rear support area. I used a plasma cutter and trimmed the support back for clearance (on the '69). I think maybe 3/8" to 1/2" from the tunnel floor on the sides, and to the inner cross member bolt holes. The height was OK at the top so I left the curved upper part. This allowed me to use straight pieces of 3/8" thick strap (the width of the cross member) to box weld back into the sides of the tunnel cross member. Likely I could have used thinner strap, but I had the 3/8" in the garage. This was for the Legend Gear & Transmission SS-700 5-speed, but should work with a 518 swap using a JW Performance UltraBell to convert to the big block bolt pattern. I'm not sure of the '73+ changes to the T-bar cross member area? With the manual trans, I did have to cut the floor sheet metal for the shifter. I think with the 518 auto, the floor sheet metal does not need to be modified?
    This old 1996 Hot rod article sort of shows the 518 swap and changes to the rear trans support area, but Use an JW Performance ultra bell, not the JVX adaptor as it pushes all the trans back another 1/2" making it even tighter to fit, and I think the ultra bell is less expensive then the JVX adaptor.
    http://www.hotrod.com/articles/43323-mopar-overdrive-transmission-swap/

    JW Performance Ultra bell:
    https://www.summitracing.com/parts/jpt-92457/overview/

    PACT has pressure switches to make a simple wiring setup for the overdrive/lockup wiring.
    PACT swap info:
    https://transmissioncenter.net/shop/727-to-518-transmission-swap-information/
     
  8. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    but how if the bellhousing is part of the case ? ?
     
  9. mopar 3 B

    mopar 3 B Well-Known Member

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    Trans adaptor plate fits between trans and engine block. One side bolts to LA trans other to BB-RB block. Uses a crank spacer to move the flex plate back.
     
  10. Nacho-RT74

    Nacho-RT74 FBBO Gold Member FBBO Gold Member

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    But the “bellhousing”?
     
  11. 451Mopar

    451Mopar Well-Known Member

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    The ultra bell replaces the stock bellhousing. You cut the original bell from the trans case and the new one bolts to the trans case at the pump with longer pump bolts. The JVX adaptor, you still have to cut the bellhousing case slightly fot the new starter location.
     
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