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Transmission rebuild

Transmission and Drivetrain

  1. Khuotakharma

    Khuotakharma Active Member

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    Hello e-buddies.
    I need a little help here. Have a 1973 Dodge Challenger. 340 cubic inch motor comma with an eight and three quarter inch rear end, 3:23 gears. Transmission is 727 torqflite.
    Gonna rebuild the motor and hoping to get 425+ horsepower out if it. Pulling the tranny soon to have it rebuilt. What are the specific upgrades I should request to improve the tranny for the engine upgrade? Also any specific parts or manufacturer? Don't know much about tranny's so I just want to know what I should be asking for. Appreciate any help.
    Thanks
     
  2. moparleo

    moparleo Well-Known Member

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    When you say that you are hoping to get 425+ hp, does that mean that you haven't figured out your engine parts combination yet ? You should pretty much know what the hp and torque output will be with a given combo of intake, exhaust, cam, etc... What is the plan? Also you really want Torque more than horsepower. Torque is what pulls you down the road. Just like you should check with engine builders about your expectations with a build you should also be checking with the major transmission builders who do Mopars as a specialty. If you just want to browse the catalogs, you can do that too. If you want the biggest bang for the buck, put on a set of quality headers and go with a lower gear ratio in the rear..something like a 3.90 will really get going quick. Just no top end.
     
  3. DetMatt1

    DetMatt1 Well-Known Member

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    Here's what I had done to mine, so far so good.

    Here are a few of the improvements made to my trans. I found a used late '90s 46RE on Craigslist as a doner for some of the mods. The valve body got a shift improver kit and the oem steel check balls were replaced with the composite ones from the 46RE as they don't beat up the separator plate like the steel ones.
    New TCI HP intermediate sprags.
    New style dimpled input bushing in pump housing for improved oiling.
    Replaced main output shaft bearing.
    Back planetary set was replaced from the oem 3 gear set to the 4 gear from the 46RE.
    Front clutch pack springs went from the 9 originals + 3 reds from the 46RE to = 12.
    Front clutch pack bushing replaced with new updated grooved style for improved oiling.
    Front clutch pack discs changed from 4 oem to 5 Alto-red .062 discs.
    Back clutch pack discs changed from 3 oem to 4 alto-red .062 discs.
    Kick down apply lever changed from 3.2 oem to 3.8.
    New front and rear bands, good ones.
    6 1/2" washers used as blocker in the low/reverse apply piston assembly.
    Removed casting flashings from case(one was dangerously close to falling off which would have been disasterous)
    This was all done by a close friend of mine whose a guru imo and I'm really looking forward to experiencing the performance of this trans.
     
  4. Khuotakharma

    Khuotakharma Active Member

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    Good morning......
    Thanks for the info. Any chance I might be able to contact your friend for some guidance on my build? Not planning on racing this thing but I do want to go fast, so I'm looking for some performance and durability.
     
  5. DetMatt1

    DetMatt1 Well-Known Member

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    I'll check with him to see if he'd be open to talking, he's retired and really busy in spite of it.
     
  6. Khuotakharma

    Khuotakharma Active Member

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    Ok. No pressure. I would just want to pick his brain a little.

    My name is Joe by the way.
    If he's open, I'll can provide my number so he can call at his convenience, if that helps.

    Thanks very much.
     
  7. Khuotakharma

    Khuotakharma Active Member

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    btw, did you choose the a518 transmission just for the overdrive? would it bolt right up to a 340? What about the a618 which is a heavier version of the a 518?
     
  8. DetMatt1

    DetMatt1 Well-Known Member

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    I just used that trans for the parts listed to rebuild the original 727. They're virtually the same internally but you get more clutch capacity, the additional gear in the back planetary, additional sprigs in front clutch pack, etc..