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| Overdrive or no overdrive? https://slantsix.org/forum/viewtopic.php?t=17292 |
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| Author: | Luthastro [ Thu Apr 27, 2006 11:43 pm ] |
| Post subject: | Overdrive or no overdrive? |
First, I want to make sure I "get it." A regular 4 speed tranny from Slant 6 days still gives the same highway ratio as a 3 speed, right? Second, an A-833 with overdrive still has only 4 speeds, right? It's just that the ratios are different, so that it doesn't have an overdrive added to the 4? Third, this all means the only way to get mileage is with an overdrive ratio? Lastly, where can I find lots about rear end ratios relating to the Slant 6? |
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| Author: | Bohmer2 [ Fri Apr 28, 2006 7:01 am ] |
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There are overdrive and non-overdrive versions of the 833 4 speed transmission. The non-overdrive final gear is 1:1, the overdrive varies from 0.71:1 to 0.73:1. more information can be found here http://www.slantsix.org/articles/4-spee ... speed1.htm A-833 OD tranny is a four speed tranny (a 3 speed tranny with an OD gear.) For highway cruising you can get more mileage out of the od, but other factors play into town driving (rear end ratio, driving style etc.) there is information all of this forum on rear end ratios, what are you specifically looking for? |
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| Author: | Luthastro [ Sat Apr 29, 2006 5:21 pm ] |
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Quote: There are overdrive and non-overdrive versions of the 833 4 speed transmission. The non-overdrive final gear is 1:1, the overdrive varies from 0.71:1 to 0.73:1. more information can be found here http://www.slantsix.org/articles/4-spee ... speed1.htm Reading that article a day or two ago is what prompted my quest for confirmation of my understanding. My first question was to verify that I understood what is actually the old version of A-833, a straight 4 speed. I think it has the same highway ratio as a 3 speed - apparently 1:1, so that a 4 speed would be totally useless as a mileage getting device. Like I said I want to make sure I've got that right. That is, before I decide permanently never to waste time with a regular 4 speed on a transportation car. Quote: A-833 OD tranny is a four speed tranny (a 3 speed tranny with an OD gear.)
My second question, again, was to confirm my understanding about the newer 4 speed A-833 - w/overdrive. I specified a particular point - whether the overdrive added a gear or merely changed ratio spread - which latter I understand to be the case (maybe I'm wrong).I bought a new car once. I had the choice of getting with or without overdrive. The one without overdrive had 4 speeds. The one WITH overdrive had 4 speeds PLUS overdrive, which made it a 5 speed in actual fact.. I shifted through 4, then went up another gear. So my specific question, as stated, was whether I understand correctly that the A-833 has a total of 4 speeds whether or not it has overdrive. Putting it another way would be saying that the phrase "with overdrive" is technically correct because of the top ratio, but it is not 4 speeds plus overdrive. One could even say that it is 3 speeds plus overdrive. That is, practically speaking, if not "sales talk" speaking. Confirming these two points would show the real difference between the two transmissions as compared with a 3 speed. One would have 4 speeds with the low end extended. The other would have 4 speeds with the high end extended. That is, compared to a 3 speed, one has, in essence, an extra gear at low speeds. And the other has an extra gear at high speeds. Quote: rear ends . . . what are you specifically looking for?
Someone said I should get, as I recall without looking again, a 2.76 rear end for highway economy. I asked if there was something less drastic than that and got no reply, so I'm asking where I can puzzle it out for myself over a period of time.
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| Author: | sandy in BC [ Sat Apr 29, 2006 6:14 pm ] |
| Post subject: | |
The Overdrive four speed was a regular A-833 with an overdriven gear set installed in place of the regular third gear. The shift lever on the side cover was flipped over to "fool" the shifter into shifting from second to fourth and then back into third, which was the overdrive gear...... 4 gears total...one of which is OD. This information came from here: http://www.slantsix.org/articles/4-spee ... speed1.htm Stay with your 3.23 gears with a 833OD and 14" tires. |
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| Author: | emsvitil [ Sat Apr 29, 2006 9:34 pm ] |
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There's a 2.93 rear gear |
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| Author: | DusterIdiot [ Sun Apr 30, 2006 10:43 pm ] |
| Post subject: | Bent six in one, and half dozen in the other... |
Mopar's 7 1/4" rear ratios in the 'streetable' range were: 2.76 - usually found behind the A904 Automatic 2.94 -found in some 60's cars behind the automatic and in some manual cars and the 1976 A-833OD equipped Feather Duster (makes for a really tall final ratio) 3.23 - usually found in 3 spd manual cars, optional in automatics The A-833OD was called by Chrysler the 3spd+ Overdrive because the first three ratios closely mimc the A-230 3 speed box, then you also have an OD gear for the last ratio...The Chrysler A-833OD is like the A-833 in most respects except for: 1) It's a wide ratio tranny so expect rpm drops between the first three gears depending on your rear ratio. 2) The front shift toggle (3-4/OD-3) is flipped to fool the shifter back to the regular "h" pattern. 3) The tranny is 'unified' in direct or 3rd gear, but when in OD due to the physical positions of the gears the OD uses the countershaft to transmit the final drive, this can be a weak point and can cause some case wear (in aluminum boxes), and some whining. The 1975 A-833OD came in a cast iron box and is considered a bit stronger and heavier. I've even heard that you can swap the tight ratio gearset into the OD box, but not the OD set into the straight box (due to the gear sizing and the input bearing hole). If you're looking for a 'sweet spot' in mileage vs. performance you'll want to look over a ratio calculator like the one at moparts.com, it'll give you a hint as to where your shift points will change and whether you'll be in the powerband at certain speeds. With that said the 'tight ratio' normal A-833 might get you slightly better in town mileage in certain conditions, but the A-833OD would probably (under certain conditions) be much better for all highway mileage (compared to the A-230, mated to a similar rear ratio). My family primarily liked manual tranny slant cars, I personally like having 3spd+OD on the floor it gets nice highway mileage. I also really like the A-230 3spd box, it's short shift pattern makes for fun throwing the gears on the floor shift...you'll arrive at your decision through some calculations, some idea of what you want , and some 'intuitive feel'. -D.Idiot "Why the Heck did my buddy leave me a car with an automatic in it!?!??! Where's the other pedal?!?!?!?" |
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| Author: | Luthastro [ Mon May 01, 2006 11:47 am ] |
| Post subject: | |
Quote: There's a 2.93 rear gear
Thanks.
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