Teach me about manual transmissions

Not how to drive them, or install them, or break them. I know all that.

I have a GM specific NP A-833. For the background, it used to be the Hemi four speed. In the 70s, Dodge had NP add an OD for a 1-2-3-OD for the featherduster. It was a neat setup. For whatever reason, GM bought the thing and made a bell for a traditional bowtie V8 pattern and put them behind Diesel trucks in the 80s. I have that transmission which I have swapped in my 72 GMC.

It's an AWESOME transmission. I love 1-2-3-OD. It looks and acts like a four speed, the bigger gear ratio spread doesn't seem to bother it, and I can run 3.73 gears with a good cruising RPM.

But.

It was a cast off unit. The input bearing is trashed. It whirrs. It's not the throwout bearing. It also needs at least a second gear synchro. I have a full rebuilt kit with all synchros and stuff. I don't know how to use it.

I fundamentally get how it works, and I touch the parts and understand where they go and whatnot, but I do not know how to rebuild a transmission.

Anything to read? Books to get? Videos to watch? Life lessons to apply?

Additionally, it had a Hurst shifter (stock) that is worn out. It is a bayonet style, and I can find nearly zero aftermarket. Hurst will still rebuild them for you for $100. is that the best option?

Thanks guys

go to moparchat.com theyve got a lot of guys running them over there. just

list it as an a833od, not the chevy version.

passion and brewers both have TONS of info on these things, and should have any parts you could possibly need.

ive rebuilt a non od a833 a couple of times. theyre not hard to work on. dont know about the od version.

Find an ancient service manual on line and follow it. The thing with any manual is knowing the sequence of disassembly/assembly, and figuring out how to get bearings off without special tools. Often to get the main shaft out, you will need to remove the front or rear bearing, and there is often a special puller involved. Most often it can be repaced with an appropriate hammer and punch, particularly if you intend to change the bearings anyway.

And have a high quality set of snapring pliers around.

Michael,

Good recommendation, that site netted me this free step-by-step:

http://www.moparmusclemagazine.com/techarticles/drivetrain/mopp_0403_rebuilding_the_a_833_four_speed_tranny/

Streetwise: Yeah, the special tools thing is going to kill me as I am on a no-spend mandate. I'll have to borrow some snap ring pliers. I don't own any and the good ones are very pricy.

Not a pricey as paying somebody to do it, or screwing something up by using the wrong tool...

Try to find a ratcheting set of snap ring pliers. They are really helpful so you don't have to hold tension while maneuvering the pliers.

I have half a dozen Chrysler ones if you find yourself needing something.

Dusterbd13 wrote: ive rebuilt a non od a833 a couple of times. theyre not hard to work on. dont know about the od version.

Fairly sure that it is identical internally, it is just that "3rd" gear is an overdrive ratio and the 3-4 shift arm is installed upside-down.

OK, a month from this and I am ready to pull the tranny out next week. I still have not found a decent manual for it. Can anyone show me where to find a good shop manual for a rebuild for this bad boy?

Thanks

Besides the old service manual, I don't find anything with my normal lookups.

Manual transmission rebuilds are the reason I love automatics.

Ranger50 wrote: Besides the old service manual, I don't find anything with my normal lookups. Manual transmission rebuilds are the reason I love automatics.

What does "the old service manual" mean? Ebay perhaps?

An actual GM service manual unless you can find one of the green cover Chiltons.

Brian: I have a complete tyree on the floor with bellhousing flywheel and clutch and shifter I just pulled from an 81 chevy truck. Worked perfectly. Free for you if you want it before i throw it on craigslist.

No thanks, Michael, I really like this transmission, I just would like a bit more in the way of a manual before tearing into it. I can make do without if needbe.

Ranger50 wrote: An actual GM service manual unless you can find one of the green cover Chiltons.

What year model are you looking for? I once had one of those Chiltons...... somewhere (off to the archives)

I found this thread on an A833 o/d box rebuild:

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Board=QuestionAnswer&Number=7424811&Searchpage=1&Main=7424465&Words=+'84+D150+Shorty&topic=&Search=true

I bet your problem is the input, or first motion shaft, bearing, they are the hardest working one and will 'whir' when they get worn.

Manuals are really pretty instinctive, or at least the old ones are. The things to watch out for are 'brinneling' of the needle bearing races and rounded teeth on the synchro hubs.

Disassembly of any of the older units starts with removal of the outer side cover then the input and tailshaft housings. Next the countershaft shaft is tapped out, allowing the countershaft to drop into the bottom of the case. Then the input shaft is wiggled and pulled out, then the rear shaft carrying all the gears can be pulled.

Putting it together is no biggie: use grease to hold the needle bearings in the countershaft then set it in the bottom of the case. Slide the assembled main output shaft in from the rear, then slide the input shaft in from the front. Once they are in, flip the trans upside down, use your fingers to align the countershaft gear with the holes and slide the countershaft shaft back in. Bolt up the outer covers etc and you are done.

Be aware that on older manual boxes getting rid of gear whine can be VERY expensive (replacing gears etc) and they will go like forever with a whine.

It was used 81-87 chevy diesels...

Curmudgeon, thanks for that link. I think you are right and this is going to have to be one of those 'just stop being a Bob Costas and dive in' things. I measured the driveshaft angles tonight and painted the bed floor bottom, so I am only a few days away from getting it out at this point.