A833 390 stroker what do I need to hold 400+ hp

Manual Transmission & Clutch Discussions

  1. cawcislo

    cawcislo Well-Known Member

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    Hello. I’ve got a 70 duster which someone converted to manual before I bought it. I have not owned the car very long and decided to upgrade the motor. Recently I turned the 318 into a 390 stroker and the stock used clutch was not up to the task. I just pulled the trans to change the Clutch and realized the aluminum A833 trans is likely an overdrive unit which is not what I want as I plan to drive the car hard and do some drag racing with it.

    I’m assuming I can keep the bell housing, Clutch fork, z bar, shifter, etc and I just need to find a regular 23 spline A833 (I’m assuming in a steel case). So long as it has the shorter a body tailhousing. Will something like that be capable of holding 400+hp at the drag strip? Any Tips on what I should be looking for and other upgrades I should do while I hunt for a trans.

    for now I’ll finish my clutch swap and take it easy on the aluminum overdrive unit. Thanks for the help.
     
  2. RustyRatRod

    RustyRatRod Lemmie see your b00bs. FABO Gold Member

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    Yup. A standard non-OD transmission will hold up fine at that level.
     
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    • inertia

      inertia Well-Known Member

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      • j par

        j par Well-hung Member

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        You shouldn't have to take it to easy except for overdrive or 4th gear or whatever you want to call it. First second and third should be good to go.
         
      • yellow rose

        yellow rose Overnight Sensation FABO Gold Member

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        The clutch will break more parts than the engine.
         
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        • Kendog 170

          Kendog 170 Let the boy go !

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          I've put the 833 guts in the Alumium OD trans before. You then have a Big front bearing and a lighter trans.
           
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          • dodgedifferent2

            dodgedifferent2 Well-Known Member

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            Exactly. Never assume it's an OD box. I run a steel passon hemi overdrive 4 speed.
             
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            • cawcislo

              cawcislo Well-Known Member

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              will it be strong? If so can I buy the gears/shafts etc to make the upgrade? Or should I be looking for a regular a833 as a parts donor for all I need?
               
            • cawcislo

              cawcislo Well-Known Member

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              One more question... my output shaft has 26 splines, is the regular a833 with 30 splines Output stronger/beefier then the 26 spline output of the overdrive?
               
            • Kendog 170

              Kendog 170 Let the boy go !

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              I had a complete Iron 833. I just swapped everything over. If I remember correctly I just changed the front output bearing to the larger size bearing. I can't comment on strength as I don't know. It was in a Dart (street driven) and I never had any issues.I still have the whole setup.Saving it for another build someday I'd like to Stroke my 1974 LA 360
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              Yur in trouble; that small-shaft came in the A/F bodies with slanties.
              If you see one lever up and one lever down then you have a boat-anchor,as regards your stroker.
              The overdrive is nice, but with a big cam, your cruise speed may put your engine into a low-efficiency rpm, and if that happens you won't save any gas money; but the reduced rpm will still be worth something, in terms of comfort.

              With an upgraded clutch, Ima thinking a scattershield is in order. The CFII for instance is so grippy that my 367 used to chirp the tires going into third gear at 85 mph. That CF PP has destroyed 3 factory 340 discs so far and the fourth is vibrating again. It busts the spring-carrier and spits out the springs.

              You will need 1350 yokes anyway and I doubt you can get them for that wiener-shaft; so that small-shaft has got to go. The larger shaft is a straight swap-in.

              Your stroker with half-decent tires, will snap 7260 U-joints. If you have to run them; I highly recommend U-bolts on the rear yoke and a driveshaft loop up front. When you buy new joints, take them apart and wash out the assembly grease, then reassemble with black moly-grease. Make sure you check and adjust your rear pinion angle to keep the U-joints scrubbing the grease around.

              If you stick with the overdrive, you gotta remember that it is NOT a 4-speed. It is a 3plus1. Take it very very easy going into od. If you forget, then you will shatter that tiny gear, and when that happens, nobody knows where the parts will go. If they end up going between other gears, well it will make a mess in a heartbeat. I blew up three of those with my 367, only one with the CFII disc.

              With a stroker,and a clutch, on the street,the thing is; you really don't need a big cam, nor a big rear gear. But the bigger the cam, the bigger the rear gear will want to be, else you end up putting the 2-3 shift rpm outtasight.
              Like with 3.23s; 6000 is about 78mph with a regular A833 (1.92ratio) but is 90mph with the od-box(1.67ratio). There is no way to get that down to 60mph , except with 4.88s.... and then you have a useless first gear starter of 15.08. And a cruiser equivalent to 3.55s. I'm just saying. You can move the shift road speeds around with the gears but with the od-box it's hard to match to a big cam; that 1.67 second gear is a real tough nut to crack.
              FYI;
              My 367 with a 223*@.050 cam, pulled anything I threw at it right down to 2.73s. I went to 3.55s because 60 was 5100, right where the power peak was. So the zero to 60 is a lotta fun.

              If you don't know it here are the ratios;
              .....2.66-1.92-1.40-1.00 regular A833 1966up
              3.09......1.92-1.40-1.00 64/65 Commando
              3.09......... 1.67-... 1.00-.73od That 1.67 is smack-dab inbetween 1.92/140
               
              Last edited: Oct 5, 2020
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