Hello,
Right now I have an aluminum cased A833 overdrive in my 72 Duster with a 318 and 3:91 sure grip 8 3/4. I'm going to look at a 360/4 speed setup that was in a 71 Dart and is soposed to have an iron case A833, dont know if its OD or not. My current trans workes perfectly but this one is also soposed to be in good shape.

Whats the better unit to use, the aluminum or the iron? I'm looking at building up the 360 to around 400HP (crank), I figure the aluminum must be alot lighter but would the iron unit be stronger? Need some sugestions. I'll know more when I take a look at it but I'm 98% sure I'm getting it in any case, figure I'll just sell whichever trans I dont use.

Any opinions?

Butch

We've used the al. 833 ODs a lot, even behind big blocks. They do okay. But they will not take a pounding. If you plan to beat on the thing, don't go with the aluminum case.

Usually the OD trans are cheap and about half the price of a iron one. The od units can be run behind a good strong motor for awhile , but its good to have spare to replace it with once it goes. The iron version is better because of long term strength and parts availability in my opionion.

The issue with the aluminum case is the trans shafts float in the aluminum case. What this means is there's a hole in the trans case and the tip of the shaft rides in this hole. What happens over time is that hole gets worn open because the aluminum is too soft. Eventually this results in poor gear meshing giving you a crappy shift and eventual transmission death. The iron case is the better case, unless you have bushings installed into the aluminum case to solve the problem, but it is a precision operation to install the bushings.

As for the strength of the guts, it's said the overdrive gear in the OD833's is weak and not suited for WOT action, just cruising, but the 1-3 gears are not any weaker than the 1-4 gears in any other 23spline 833 with the 3.09 1st gear.

Thanks for all the info guys. Maybe I'll just keep both, use the od for now and if it dies swap out to the iron.

Butch

I picked up the motor and tranny, its an iron case trans with thes numbers...

C-99386 on the cover
C-99129 on the side of the case
C-99126-1 on the tail shaft


Can anyone id this trans, it also apears to have a 4 3/8" bearing retainer. Any idea if its OD or not, if not what kind of gears did these have?

Butch

We have an aluminum case unit in the shop going behind a 427 inch small block. This is for a road race/track car.

Stock, the OD trans only had a 5.125" retainer.

Ok the best I can tell the numbers on the ID pad are as follows...

4B297511
PP83 4575

Does that help any? So it looks like its a non OD tranny which sounds like its good if I build a motor with some serious power, but maybe better off with the OD for a 400-under 360 street motor with 3.91's

Butch

Looks like a 1974 transmission. This is the close ratio unit made from 71 to 74. Best for winding road driving.

If you don't want it ........

Bob

Looks like you have a few 4 speed cars!!! What is the first # the year?

So would this tranny be better for street perfomance than the OD? Dont really get over 60MPH much, just cruising around town, like to get from 0-60 as fast as posible .


Butch

Here is a shot of a Passon aluminum cased four speed behind a 427 inch small block. This tranny was 40 lbs lighter once all the goodies were installed.