Anyone running a 904 behind a 340?

Transmission and Drivetrain Tech

  1. dibbons

    dibbons Well-Known Member

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    Just wondering how it might hold up, must be some "over-engineering" from the factory in these smaller Torqueflites.
     
  2. 70aarcuda

    70aarcuda Master Hoader of SBM FABO Gold Member

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    skip the 340...got 904s behind 360s....
     
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    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      I have an A&A style 904 with an 8 inch Turbo Action converter for my 340. Cope Racing Tarnsmissioms is who I got all the tranny parts to beef it up from.
       
    • dibbons

      dibbons Well-Known Member

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      I'm sorry, not familiar with what was referred to as "A&A style" in the post above.
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      A&A transmission makes the internal spring kit that you need to replace the factory reverse wound spring. I like working with John cope with cope racing Transmissions that's why I bought the parts from him rather than from a&a that seems to be operated by a butthead.
       
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      • 70aarcuda

        70aarcuda Master Hoader of SBM FABO Gold Member

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        ati make a less expensive alternative to the 24 spring kit....looks just like the stock spring but is wound the opposite direction...20 bucks
         
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        • Jadaharabi

          Jadaharabi FABO Gold Member FABO Gold Member

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          KOOL.

          I'll get one for my backup trans.

          Thanks for info
           
        • cannucky

          cannucky The Guy With No Birthday

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          got one behind a 520 hp 410
           
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          • fishy68

            fishy68 Tyr Fryr's Inc.

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            Running one behind a very torquey 408 with a 4000 stall converter. Holding up fine in a 3470 lb car
             
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            • MoparLeo

              MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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              I guess Mopar wasted a lot of money engineering the 727-A. Here is some reading to educate those out there who would like to understand some of the "buzz words" out there. Really some good facts for anyone who takes the time to read it. BTW why not save it to your transmission file. You have one don't you ?
              Tom Hand's guide to the Chrysler torqueflite automatic transmission
               
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              • abodyjoe

                abodyjoe Well-Known Member

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                with quality parts and someone who knows what they are doing assembling it the 904 is the way to go..
                 
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                • Toluene56

                  Toluene56 Well-Known Member

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                  904's are good.. have one behind my 410.
                   
                • fishy68

                  fishy68 Tyr Fryr's Inc.

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                  Yes and no. Back when they were made the friction materials weren't as good as today's stock replacement clutch plates and bands. Also given the fact that the factory tolerances were all over the board made the design of the 727 the fool proof one to go too behind a high perf engine. Were lucky today to have the benefit of much better friction materials and have figured out what clearances work best so we can make a 904 live behind something making twice the power it would originally handle.
                   
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                  • MoparLeo

                    MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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                    So if you are looking to put a 904 behind a 340-360 HP motor, you should first have the trans built with modern parts. Yes ?
                     
                  • Demonracer

                    Demonracer 71 Demon 00 Ram 16 Chrysler 300S 05 Caravan FABO Gold Member

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                    I have a 904 behind a 620 HP 416 stroker in a 2600lb car, no problems. Less weight, less reciprocating mass, good launches, 1.50ish 60' times, 9.40 1/4 times, what else can I say...
                     
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                    • crackedback

                      crackedback FABO Gold Member FABO Gold Member

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                      The old parts still work at that level with good tolerance control. The new frictions are tons better and the tweaks available make 904's even better.

                      I'm not a fan of the 727 bombblast front drum. No such issue with a 904.
                       
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                      • 70aarcuda

                        70aarcuda Master Hoader of SBM FABO Gold Member

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                        I would hope after 40 yrs or so that all the old parts are sold...LOL

                        Should be firing up a 410 small block in a couple of days with a 904 behind it...I think I got 5 904s in use...sometimes I lose count...getting old..but my parts still work...LOL
                         
                      • dibbons

                        dibbons Well-Known Member

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                        Well, I recently had the 904 I have rebuilt (Fresno) and asked the owner of the trans shop to install a shift kit. He said he does that anyway, so I just got his "regular" rebuild. It seems to shift very smoothly and very quickly, which I like. The strange thing about the rebuild is the shop gives 3 years or 50,000 mile warranty, which for me is unheard of (i expected something like a 6 month warranty).

                        Anyway, when I put together the "stockish" 340 I need to rebuild, it will replace the stock '72 318 which is in the car now with the 904. I guess the 340 will go in just the same as the 318, except for one of the motor mount brackets and one of the transmission to engine braces.
                         
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                        • Duane

                          Duane Well-Known Member

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                          Are you only referring to clutch pack clearances. A friend of mine locally runs a 69 dart 11:20,s with Griner brake which he claims has low band apply. Launches wheels up every pass. He just destroyed his roller clutch. Cannot get the drum out of the case. Claims to have an aftermarket reverse servo. Drum,band,and servo all in good working order. Anyone care to explain this failure. He thinks he needs the new better aftermarket roller clutch. He says the trans is late 1960,s model. This motor is a 360 cubic inch with j heads.
                           
                        • dibbons

                          dibbons Well-Known Member

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                          While we are on this topic, what flexplate are you all using with this 904 setup? Factory or aftermarket? Part number? Thank you.
                           
                        • fishy68

                          fishy68 Tyr Fryr's Inc.

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                          the clutch plate clearances and the end play setting
                           
                        • MoparLeo

                          MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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                          We always hear the stories of " I use behind bla, bla, bla and never a problem." My dog is bigger, what ever... There are pros and cons to every application. True the 904 has less reciprocating weight, lighter bla,bla,bla...OK The 727 are in normal applications, bullet proof. Most applications. Lets try to talk about what Joe Mopar should expect in stock condition on his application. Yes you can have anything built to withstand anything, but not everybody uses them for racing. A race car is a race car, a street car is a street car. Not the same. A race car only has to do its thing for a very limited amount of time. A street car has to live for a much longer time in many different driving conditions. Not on a track. Either trans will live for a long time in 90% of the typical applications our members will encounter.
                           
                        • Demonracer

                          Demonracer 71 Demon 00 Ram 16 Chrysler 300S 05 Caravan FABO Gold Member

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                          I run SFI flex plates, but my application is race only. When I had street cars, I ran OEM flex plates but they were thoroughly inspected for cracking.
                           
                        • rumblefish360

                          rumblefish360 So close, yet so far away FABO Gold Member

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                          That is one of the craziest statements I have ever read here. It’s gotta be satire! Otherwise, how do you figure that! The 727 came out a good bit before the 904 and has won awards on a few fronts.

                          Read below.
                          THIS ^^^^^^^^^^^

                          The factory flexplate is fine for most cases of upgraded engines and such. The SFI parts, while much stronger & capable, are really not required on most street driven vehicles. If you don’t have one or it makes you feel safer to use one, then use it. There is no real downside. Except cost.

                          I normally pick up a B&M flexplate if I don’t have a factory unit.
                           
                        • CudaFactHackJob

                          CudaFactHackJob FABO Gold Member FABO Gold Member

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                          Duane, the springs in the sprag are over fifty years old. They crack and split apart. Then the rollers fall over 90 degrees and get jammed up. The drum is probably undamaged. But the riveted in sprag has to go, so drill out the rivets from the back and the drum will pull out with the sprag.
                           
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