how are the 833 overdrives???

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I have one behind the 360 in my 68 Barracuda with 3.55 gears. I have no issues at all with it at all. The 360 pulls the wide gear spacing with no problem (I have run a best of 13.7 @ 102 with a very traction limited 2.2 60').

It may not be the best choice for a drag car but for street driving it's a good choice. I get 17-18 mpg around town and 21-22 on the hiway. I am turning just a tick over 2000 rpm at 70 mph.
 
I have one in my '72 Duster w/ 318 and a 3.23 7 1/4. The 3.23 is a little high for the OD at 60mph so I have plans to change them out with a 3.91 8 3/4 as soon as the 7 1/4 gave up which happened last week. It isn't all that bad gear spacing wise. It is really no different gear spacing wise than running a three speed but will an added gear for the freeway.


Chuck
 
I have one in my 74 duster with a 340 and 3:92 gears. Highway driving is fine, but in town there seems to be too much spacing between gears. There never seems to be the right gear to cruise in. Next summer I will try one of my regular 4 speeds to compare.

The good part is...it is a cheap alternative to the aftermarket 5 speeds. Still allows resonable around town driving and keeps the rpm down on the highway.
 
The short tail shaft versions were in the mid 70's A-bodies and after that in F-bodies. The long tail shaft version was in light duty pick-ups and vans.

You can use a long tail shaft version in an A-body with very little extra fabrication. I have one in my 68 Barracuda. I had to fabricate a bracket that would position the shifter forward from the rear mount to the A-body position and you need to shorten the drive shaft. BIGBLOCKDART.COM has a nice diagram for the bracket.

340duster, I am surprised you aren't happy with the around town cruising. I know I have 3.55 gears but if I am above 40mph it's in 4th and below that down to crawling speeds it's in 3rd. I only find a need to use 2nd if I need to make rapid acceleration and 1s is only used to pull away from a stop.
 
I see. I'm not really farmiliar with them at all. I'll probably just end up keeping mine an auto anyway.
 
also when comparing the a-833O.D. you must consiter the alum. case with the iron case powerwise I would not really trust an alum case behind a high power engine. personally I think the alum case would be good behind a slant six that the owner wants to get good MPG with.
 
71DartGuy said:
What kind of vehicles can you find those in?
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mostly in the dart light's and the feather dusters (for the A-body short case) but they were in anything that had a 4 speed option (pickups, vans) Also I think the f body cases were short but it has been awile sine iv seen an f body with a 4 speed. And I dont really belive it but star parts also lists them for early jeep cherokee's and wranglers. but iv never seen them with one, just the t-4,t-5,& the asian warner's
 
I got mine out of a '75 Scamp that I purchased complete for parts. It is the cast iron version. I originally thought it was a standard one because it is iron but learned that there were iron OD's in '75 only.


Chuck
 
The 833 OD trans was created by putting an overdrive gear ratio in the 3rd gear position. Then the lever on the side of the trans was flipped upside down. This causes the shifter to shift the trans in this order: 1,2,4,3, Since 4th gear was a 1 to 1 ratio, the 3rd gear (shifter position) is now 1 to 1 & the 4th is now an overdrive ratio (.73 to 1). With a normal transmission, 4th gear power would go straight through the mainshaft to the output shaft, while in the OD trans 4th gear (the overdrive ratio) is mounted in the 3rd gear position and the power in high gear is going through the countershaft & then back to to the output shaft. It's my understanding that the biggest weakness of this design is that since 4th gear power goes through the countershaft there is a high side load on the countershaft & trans case while in 4th, which is where the trans is the majority of the time. The powertrain also has the most load because this is where the total gear reduction is the least advantageous. Chrysler increased the size of the input bearing to help prevent wear because of this. I've also read somewhere that the aluminum cases tend to wear out where the countershaft is inserted into the front of the case. I think this can be fixed by bushing the hole. These transmissions also have a larger diameter input bearing retainer, (5.125") so they normally need the corresponding bellhousing. Some of the other transmissions used the same bearing & had a smaller diameter (4.8") retainer, so swapping the smaller retainer will allow use with a bellhousing with a 4.8" hole in the back. Supposedly these transmissions were not designed for high performance but I know I've seen at least one magazine article where somebody was using one in a Superbird.


:burnout:
 
Any gear but direct goes thru a counter gear shaft in any manual tranny. As stated it is the cluster gear shaft were it is mounted to the case on the aluminum ones that is the weak link.


Chuck
 
probably be good... the other problem is the big jump between gears.. the rpm will drop quite a bit. not great for performance.
 
I've got four myself. I've also hear that the cast iron is a little stronger. Don't know who I heard that from.
 
abodyjoe said:
probably be good... the other problem is the big jump between gears.. the rpm will drop quite a bit. not great for performance.
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I had the A833OD behind a \6 for about 3 years and 30k miles and the gear jump between 1/2 or 2/3 was not a big deal but 3/4 was. Now that i have it behind a stout 360 it's not a big deal period.

It may not be the best spacing for maximum acceleration but on the street it's fine. My car with that tranny and 3.55 gears has run a best of 13.7 at 102 mph. My problem with getting to the low 13's or high 12's is traction off the line, not the gear spacing. The best 60' time I have been able to achieve is 2.2 seconds.
 
dgc333 - the reason you are having traction problems (onther than tires) is the 3.09 first gear. It is significantely lower than the regular 3spds used in the early 70's behind 340s. As well the regular 4spd was a 2:66 first gear.

Saying the aluminum case is the weak link may be valid (or may not) and stems from some documentation is the old mopar chassis manual stating that this is a weak case. I think the real problem is that the countershaft is shorter and only engages half of the transmission case (the iron one has full engagement. An expansion plugs is used in the other part of the case presumably to reduce leakage. Having said all that I have not seen yet an OD case that is worn out.

Again IMHO, I would also like to state again that the spacing between gears is wide. A regular a-body 4spd is 2:66 1st gear and 1:1 for 4th. The OD unit is 3:09 1st gear and .73:1 4th gear. That is a huge difference. As I mentioned before my current driver has the OD 4spd and I really don't like it due to the gear spacing. The rpm drop is very noticable between gears, it seems like you have to rev it way up in every gear so it won't lug the engine in the next gear. It is definitely useable and drivable and is a good cheap way to have a car that has good acceleration and still have a car that can be driven on the highway. But it is far from perfect. If I could afford it a 5 speed would be the answer. Just ask anyone who has installed a 5spd, most are very happy with it and say that is the best modification for drivability they have done.
 
340duster said:
I have one in my 74 duster with a 340 and 3:92 gears. Highway driving is fine, but in town there seems to be too much spacing between gears. There never seems to be the right gear to cruise in. Next summer I will try one of my regular 4 speeds to compare.

The good part is...it is a cheap alternative to the aftermarket 5 speeds. Still allows resonable around town driving and keeps the rpm down on the highway.
Click to expand...

what rpm do you usually turn at 75 mph?
 
I'm going to put 3.91's in mine. With the .73 OD ratio is will be like having a 2.85 rear gear. At 75mph with a 26" tire it will be about 2800rpm in OD and 3.91's.

But this will also shorten your first gear. 3.91 + 3.09 = 7.0 first gear ratio. You will be grabbing 2nd gear probably before you clear the intersection.


Chuck
 
My 64 273 came from the factory with these transmission gears: 3.09, 1.92, 1.40, 1 to 1, & 3.23 gears in the back. I read an old magazine test article that said shifting to 2nd gear was like stepping off of a cliff.....there was nothing there, & I would have to agree with that. I later switched to 3.91s & found myself (as mentioned above) shifting almost before I cleared the intersection, & then still having a large drop in RPM as I went into 2nd. With the lower torque of the 273 I'm sure this was a lot more noticeable than it would be with a 360. I have a guy coming by with an A/F body OD trans for me to look at. I have a rebuilt trans with a 2.66, 1.91, 1.39, 1 to 1 gearset that I think I'm going to run behind my 360 most of the time, but I can always "stab the OD trans in there" if I need to make a long highway trip (sure, swapping transmissions is easy!). Now, if I had somebody who would swap transmissions for me I'd really have the best of both worlds!
 
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