Change from 4-speed to 3w/OD

Manual Transmission & Clutch Discussions

  1. Kelster

    Kelster Member

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    I have a 63 dart wagon with a 360 and 4 speed trans that I want to change to a 3 speed with OD. I run 70 mph's at 3000 rpm's and I just don't want to ware out my motor. What are your thoughts and where do I look for this transmission?
     
  2. hemi446

    hemi446 Well-Known Member

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    Look for 75-82 maybe pickups or F bodies that is all I know of that came with that overdrive transmission.
     
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    • RustyRatRod

      RustyRatRod Bla de blizhibliz de blatde blizi bla bla

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      No, you want to change from a four speed to a four speed OD. The Chrysler four speed OD transmissions still carry the A833 designation. That means they are a four speed, not a three speed. If it has four forward gear, it's a four speed. I never understood why people incorrectly call them 3 speed over drives. There were three speed over drives made, with ONLY three forward gears and high was OD. But the A833 tranmissions are ALL four speeds.

      You will need a different bellhousing or you can have yours possibly machined to fit the larger 5.125"bearing retainer in the OD transmission.
       
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      • dodge71demon

        dodge71demon Well-Known Member

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        If you do this you will notice a big change in your car and not for the better very low 1st meaning shifting soon but need to build rpm's for the big drop into 2nd third is 1-1 then the OD stay with the 4 speed and slow down what rear gears do you have -- maybe change them to a high 2's or low 3's
         
      • dodge71demon

        dodge71demon Well-Known Member

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        From Allpar
        Chrysler described the change as “an A-833 four-speed transmission, converted over to a three speed manual transmission with an overdrive gear ratio.” It was used with both the 318 V8 and 225 slant six. After the 1975 run, Chrysler switched to a finer-pitched gear tooth design to reduce the noise of the 1975 models, and changed the overdrive from 0.73:1 to 0.71:1. It used a steel housing except on the Feather Duster and Dart Lite, where it had an aluminum case and extension housing.
         
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        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          Except, there's all kinds of inaccuracies right in that statement. For example, sometime after '75, maybe '76, ALL of them had aluminum cases. Only the '75 A body 833OD's were all iron case, and at some point they switched to aluminum main cases with iron extension housings, then all aluminum. There are tons of later truck 833OD's with the long b/e style extension housing that are all aluminum. The gear ratio change wasn't by year per say either, it was by application. Trucks got the .71 overdrive, cars kept the .73 overdrive. They kept the 833OD around longer for trucks, so again at some point all the 833OD's transitioned to the .71 overdrive, but it wasn't right after '75.

          Allpar is nice, but it's not a "written in stone", 100% accurate source for everything.

          Better info on the 833's and 833OD's here 4 Speed Transmissions transmission

          As far as what to call it, do you call 5 speed transmissions 4 speeds with overdrive? How about a 6 speed like the T56? Is that a 4 speed with dual overdrive? Nope.
           
          Last edited: Jan 31, 2018
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          • Chained_360

            Chained_360 Delusional Member

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            I call my A833OD a three speed with an overdrive because only the first three gears are useful for going fast. If you try to put 300 lb-ft of torque through the overdrive gear, you're probably gonna strip all the teeth off of it. Therefore, it has three speeds for full throttle, and one speed for cruising. Just my 2 cents, because you are technically correct.
             
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            • ConValiant64

              ConValiant64 Well-Known Member

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              I have to respectfully disagree with RustyRatRod. I agree that forward gears should be counted, but only until you get to a 1:1 gear ratio which, in the case of the A833 OD tranny, is 3rd gear. '4th' gear is an overdrive ratio, thus, it truly is a 3-speed overdrive. Hate how tight 1st gear is to 2nd. It's like the Power Glide of manual transmissions.
               
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              • 72bluNblu

                72bluNblu FABO Gold Member FABO Gold Member

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                So, like I said above, a T56 is a 4 speed with dual overdrive then?

                No, it's a 6 speed.

                And actually, in the 833OD the gear that's the OD gear is actually 3rd gear in the box. It's 4th that's still 1:1. That's why the shift lever is flipped on the 833OD boxes.
                 
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                • Chained_360

                  Chained_360 Delusional Member

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                  Again, you are technically correct. But a T56 won't grenade itself at WOT in 6th gear.
                   
                • ConValiant64

                  ConValiant64 Well-Known Member

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                  My bad-meant 3rd gear.
                   
                • 72bluNblu

                  72bluNblu FABO Gold Member FABO Gold Member

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                  Only a matter of horsepower, you can grenade anything with enough juice. Put 1,000 hp in front of it and you can lunch a T56 too. Still a 6 speed, just like the 833OD is still a 4 speed. Has no effect on what you call it.
                   
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                  • ConValiant64

                    ConValiant64 Well-Known Member

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                    Makes sense to me. Let's call it what it is, people!
                     
                  • TF360

                    TF360 Well-Known Member

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                    Why don't you change your rear end gear ratio. I had a 360 Duster one time and I pulled the 8 1/4 rear end (3.23's) and put in a junk yard 8 1/4 with 2.43's. I cruised that 360 45 miles to work on the highway for a while.
                     
                  • 72bluNblu

                    72bluNblu FABO Gold Member FABO Gold Member

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                    That's fine for an engine with a small cam and an auto. If you don't make any power below 3k and have a 4 speed, you can't just toss in a set of 2.43's unless you like burning clutch.
                     
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                    • Marcohotrod

                      Marcohotrod Well-Known Member

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                      Kelster-what is your rear gear and tire size? 3000 at 70 is no big deal. change oil + filter more. go to a taller rear tire. the 1:1 gear in an overdrive, call it whatever is strong-the same as all a833 units-I ran 12s with around 450 torque, and the overdrive gear is strong too. call it a 4 gear. my buddy, seaweed the junkmaster , sold me this unit cheap, all aluminum with an iron sidecover and iron front bearing retainer, we turned down the front bearing retainer to 4.80", easier than enlarging the bellhouse (if u have a 4.35" house-not so) and 27 spline output, 308 front bearing, and I banged on it for a few years no problems DSCF0250.JPG
                       
                      Last edited: Jan 31, 2018
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                      • dirty white boy

                        dirty white boy 47 yr old Juvenal delinquent

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                        this!! AJ be by later and brake down the math on the rato's, he good at it!! its a great idea for your delima in theory but the rato's dont work out!
                         
                      • 67Dart273

                        67Dart273 FABO Gold Member FABO Gold Member

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                        You guys can call an A833 OD a "3 speed" all you want but all you will do is be incorrect an confuse others.

                        WHEN YOU BUY something like A Spicer 5 speed used in heavy trucks, some models of the gearbox are direct 5th and some are overdriven 5th. THEY ARE NOT KNOWN as a "4 speed with overdrive" they are known as a FIVE SPEED.

                        An A833 is a 4 speed, overdriven or direct.
                         
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                        • 67Dart273

                          67Dart273 FABO Gold Member FABO Gold Member

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                          THIS is an example of a 3 speed overdrive. It is a 3 speed gearbox

                          36047424f8b27e0bd1452bfddcb90680c703d9f.jpg
                           
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                          • yellow rose

                            yellow rose Overnight Sensation FABO Gold Member

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                            The OD box has the same first gear as the 3.09 box and I use the 3.09 box. I don't understand how the split bothers anyone.


                            BTW, those who say it's a 4 speed overdrive are correct. It has 4 forward gears and it happens that 4th is direct and 3rd is overdriven.

                            4 speed overdrive is what it is.
                             
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                            • Kelster

                              Kelster Member

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                              I'm kinda with you on this.
                               
                            • RustyRatRod

                              RustyRatRod Bla de blizhibliz de blatde blizi bla bla

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                              I aint the least bit interested in what Allpar says. The designation stamp begins "A833XXXX". That's a 4 speed designation. End of story.
                               
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                              • Kelster

                                Kelster Member

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                                Wow! I think I got more than I bargained for. I will copy all this info and share it with my mech. And thanks all of you for your participation
                                Bare with me I'm new at this. I think we should all agree that this is a 4-speed, if you want to say 3-peed plus OD that would be cool by me even if it ain't proper.
                                Rear gears 323, The back tire is much larger not sure the size, the issue is I want to go faster than 70 and I drive this car a lot and the speed limit where I drive 30 to 60 miles a day is 75 and you'll get runned over if your e not doing 80+, and I'd like to get better gas mileage
                                This is what I understand with out knowing all the science: 1st is shorter, second is longer, 4th is 1:1 but is now actually 3rd gear, the old third gear is now flipped around or something and is now the OD, I also understood this trans will bolt right up, shifter is the right place and everything.
                                 
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                                • RustyRatRod

                                  RustyRatRod Bla de blizhibliz de blatde blizi bla bla

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                                  Post up some pictures of your car. We'd love to see it.
                                   
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                                  • Kelster

                                    Kelster Member

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