I was going to use a somewhat built slant and regular 833 in my 65 Dart wagon and use a 3.23SG ratio in my 8.75 (or 3.21SG in an 8.25). I have obtained an A Body 833OD that I'm contemplating on using instead of the regular 833. I figure I ought to be using at least a 3.55 or even 3.91 with the 15 in tires I'll be running and the OD. Comments pro or con?

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

Well dont know for sure what the gearing is on the 833, but i had posed some gearing questions on another forum and was given these as the ratio's of the 833od:
1st- 3.09:1
2nd-1.67:1
3rd-1:1
4th-0.73:1

That being said, a 3.23=2.36 on OD... so its pretty long winded in OD.

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MRO....

Cheap, Fast, Reliable.... Pick 2...

I'm running a somewhat built slant with the OD box in my '76 Dart. Currently there is a 2.76 geared 7.25 axle under the car! It takes a bit of throttle to get it moving, but sure idles down the freeway real nice. I'm fixing to stab my 3.23SG 8.75 under it soon. I don't think it will affect my mileage at all, and should make the car nicer to drive in town. It's not under the car yet though, so I can't tell you for certain.

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The OD in my car is .73 or so . When I had the 3.23 in the car it was a little too high a gear with the stronger motor.....so I went 3.55 and was much happier. I would go 3.73 except 1st would be too low. (5 speed)

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Yeah....Im the one who destroyed this rare, vintage automobile.....

had 3.55 gears in two trucks ...was abit tall....put 4.10 in and was very happy with it...still have 4.10 and limitedslip diff for 8 1/4

It's the granny 1st gear that makes things less fun...

3.55 with the OD will put you at 2.56 or so in OD on the highway...a little low on the rpm/mph scale but it will cruise fine (did this with my '76 Feather Duster which should have about 500-600 lbs + driver on your dart). Good cruise and mpg with this combo, easier to get off the line in 1st...

I think the 3.91 ratio or the 4.11 ratios are about right for OD (final ratios being about 2.85 and 2.99 respectively...is about like having a 2.94 rear and a 3 spd).

Said duster now has 4.56SG and OD...1st gear takes no pedal to get it off the line (you can go from 0-15 mph in the carb idle circuit), ratio is kind enough that even one dead cylinder in your block will allow you to drive back and forth to work with a "miss"...but on the top end with a 3.31 final ratio it is somewhat "limited" compared to the others since my rpms are higher at highway speeds and on the track it seems to get back up to the needed rpm sooner than the 3.55's but tops out quicker...next rear end will be either the 3.91 or the 4.11...

-D.Idiot

According to my 65 Data manual the regular 833 ratios for both the 225 and 273 are
1st - 3.09:1
2nd - 1.92:1
3rd - 1.40:1
4th - 1.00:1
The engine and trans (flanged for the B & T) came out of a 65 Valiant.

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

I ran this transmission in front of a 2.45 geared axle in a '65 Dart, and it worked OK. Freeway driving was fine, I could run around town in 4th without to much problem. You really had to slip the clutch when starting out on steep hills.

You would not win a drag race and I would not run that axle in front of an automatic.

With a longer duration cam I think you're going to be happier with the closer ratios of the standard A833. The RPM drop between shift with the OD box is pretty severe and not much fun without a lot of low RPM torque.

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Joshua

I was told 3:91's would be 3:21

Not true?

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

3.23/.73=4.42
2.94/.73=4.03
or
3.91x.73=2.85

I can also do the math for the RPM drop on gear changes. Just give me the up-shift RPM. I even have a spreadsheet for that job.

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Joshua

Yes you are probably correct on the gear ratio's for the 833, My posting was for the 833OD (actually a 3sp w/OD)

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MRO....

Cheap, Fast, Reliable.... Pick 2...

My #2 Van has an A833 OD, with a 3.21 rear. Since I have an older 1 ton van for towing, I've left the 3:21s in the newer van. If I was to tow with the newer van, I'd probably find a set of 3.55s or 3.90s. With the 3:21s you dont even think about getting into 4th in town.
That being said. The newer van (an 87 3/4 ton Maxi) gets great mileage for a full size truck on the freeway, typicaly better that 20 MPG if I keep it below 70 on the hiway.
To your question. As a ball park figure. 3.23 with a .73 overdrive would take 4.42 would give you the same effective top gear. I'm thinking that 3.90s or 4.10s would let you have yor cake and eat it to. Much better launch, and a bit better top end.

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66 Valiant, 225.
84 Van, 225.
71 Maxi-Van, 318
60 Valiant wagon, 225
87 Maxi-Van, 318 4spd

No, it's a 4-speed with overdrive 4th gear.

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Too many people who were born on third base actually believe they've hit a triple.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick