A833 gear interchangeable?

[mc707]

I have a close ratio a833 that I would like to swap gears.i can get my hands on a 64-65 flange style a833.would the gears be interchangeable?

 

[413]

All the gears yes, but not each one individually. Different tooth counts.

 

[65 Cuda 340]

The original gears in my 65 Barracuda are in a later trans (69 I think, can't remember for sure) with a conventional style u-joint. So, yes, the early gearset fits into a later 4-speed.

 

[mbaird]

I have a close ratio a833 that I would like to swap gears.i can get my hands on a 64-65 flange style a833.would the gears be interchangeable?

Just get a u-joint adapter for the early one and sell the close ratio … ( T/A or AAR trany ? )

 

[Inertia]

You basically change the output shaft/tail-housing, but all gearsets must stay together, they are different ratios, and a "matched set".
The gearset in the flanged trans have the ultra-low, 3:09 first gear. Stump puller.

 

[mbaird]

I would rather have the 3.09 1st of the early trany myself . That way you can run 3.55s or 3.23s and have both a low 1st and hiway cruising speeds .

 

[mc707]

it’s the 2.47 gear set . I’m running 3.73 at the moment .

 

[mc707]

it’s the 2.47 gear set . I’m running 3.73 at the moment .would the bearing retainer from the early a833 match the bell housing i currently have

 

[Inertia]

I'd spend some time "search"ing "3:09 AJForms" posts, he's very well experienced in all gears and trans gears combination.
He has posted the "best" combos.
The main thing is hitting the right ratio cuz the jump from 1st to 2nd is a substantial rpm loss, - with the wrong gearset . . . You may be disappointed.
I tagged him, he's usually not far away.
He may also have just the tailshaft and housing you need to convert.
I got a of few flange pieces from those I have converted to slipjoint.
@AJ/FormS

Good luck

 

[65 Cuda 340]

I have 3.23 rear gears in my 65 Barracuda. With the 3.09 low gear I had originally and now have in the later case, the overall low gear ratio is 9.98 to one (3.23 x 3.09). When I first put the later trans in back in the seventies (the original mainshaft had a groove worn in it and at the time I could not find a replacement early style mainshaft) my overall low gear ratio with its 2.66 low gear and 3.23 rear gears was 8.59 to one. That low gear ratio was essentially equivalent to running 2.76 gears behind a 3.09 low gear. HUGE difference off the line. Turned a good running 340 into a dog. Had to put up with that for a couple of years, until I learned the original gears would fit in the later case. Fortunately, I had saved the original gearset.

By the way, with a 2.47 low gear and 3.73 rear gears, the overall low gear ratio is 9.21 - taller than the overall low gear ratio with 3.23 gears and a 3.09 low gear.

I never had a problem with the rpm drop from first to second. Just wind it a little tighter in low. I run it out to 6500 in low gear, 6,000 in the top three gears.

The worst transmission gear set for any kind of street gears was the old GM close ratio 4-speed with its 2.20 low gear. To get an overall low gear ratio equivalent to my 65 Barracuda with the GM low gear, you'll need 4.56 rear gears.

Back in the (recent for me) day, those 5 liter Mustangs were quick off the line because they had something like a 3.35 low gear. Gave them an overall low gear ratio of better than 9 to one even with 2.73 rear gears.

 

[mc707]

So if I were to just run the close ratio the way it is, it wouldn’t be the worst thing ? The car is currently automatic. I personally have nothing to go by.Just what I’ve been reading.

 

[65 Cuda 340]

So if I were to just run the close ratio the way it is, it wouldn’t be the worst thing ? The car is currently automatic. I personally have nothing to go by.Just what I’ve been reading.

If you're keeping the 3.73 rear gears, I think it would be fine.

 

[mbaird]

So if I were to just run the close ratio the way it is, it wouldn’t be the worst thing ? The car is currently automatic. I personally have nothing to go by.Just what I’ve been reading.

It really depends on your engine build and intended use . If you have a big cam and want to street drive it the tall 1st gear of the close ratio trany will make it jumpy at low speeds . I run a 2.67 1st gear in my 69 Swinger with a 408 and 246/250 - 108 -.648 lift cam . With 3.55s I can feel the pulses from 900-1300ish rpms . I have an early 833 with a 3.09 1st but it’s a trunion trany . So my plans are to swap the current main shaft to the existing trany . That way I get the 1st gear driveability and can do freeway speeds at a reasonable rpm . Remember … getting the car moving from a standstill and 4th gear pulls require the most power . So best of all worlds! If my car was a dedicated drag or autocross car the close ratio would be a better choice.

 

[mbaird]

And I see you are in SF ( love SF !) so you have steep hills to contend with . A 20% change in gears will definitely be noticeable when you’re at a stoplight on one of those hills . Hint… line lock is for more than just racing .

 

[AJ/FormS]

it’s the 2.47 gear set . I’m running 3.73 at the moment .

Hey, how's going eh?

As others have said;
Application is everything.
This presentation will be for a small-cammed SBM, for street in say a 3400 pound car and driver, with occasional hiway blasts..

Hiway usage is key so lets start there.
Without an overdrive, your 3.73s will get you 65= 3020, with 27" tires. This is ok for short blasts say 30 minutes or so. I never loked cruising that high, because it wears out my expensive engine about 35% faster; plus, it's loud, and I felt sorry for her. You may not have the same feelings, I can't say.
Ok so, we have established that, 3.73s are correct for you, as the maximum hiway gear..
Next, in importance to me is where second gear is. I don't much care about first because I have a clutch.
Here are the A833 available gearsets.
247-1.77-1.34-1.00; splits of .717/.757/.746
2.66-1.92-1.39-1.00; splits of .722/.724/.719.
3.09-1.92-1.40-1.00; splits of .620/.729/.714
3.09-1.67-1.00-.73od; splits of .540/.599/.730

still talking about Second Gear, my 367 likes a minimum of 6.20 roadgear , cuz that will get me 65@ 5000, where I shut down. If you have a stock-cammed 318, this will be too high a rev for it, cuz they're done at 4400; so 5000 is quite a stretch.
If you have a 276/286/110 cam like I do, this is too low. So I run up to 7.20, for 65=5830.
So lets say you had a 340 with a stock cam, that peaks around 5000, and pulls pretty good to say 5500. As you can see above, there are 3 Second gears to choose from. The 340 will like a 6.79 roadgear, which divided by 3.73 rear gear, is a 1.82 Second.
Now look at the available Seconds. You got 1.77 and 1.92 , with 1.77 being the closer one, which will get you 65=5350..
> and now we come to First Gear.
I built my engine for gobs of low-rpm torque, so she'll pull just about any rear gear, and I have proved it. My go-to is 10 pounds per cubic inch, so at 3650/367, my first gear choice is 9.95, which, with 3.23s would be a 3.08 low gear. but with 3.73s would be 2.66. It's almost like the factory had it right.
But
in the beginning I specified a weight of 3400. Suppose you have a 318. Then, 3400/318= 10.69 starter gear, and with 3.73s, that is a 2.87 First gear. So, obviously, the 2.47 is way out in left field, about 16% low.
If yur 318 is a stock low-compression model, this is gunna suck. Yur gunna need to pump up the low-rpm torque, that same 16%, to get you back into the game.
To use that close ratio trans, and have fun, your choices are;
1) rev the engine up higher and slip the clutch out, or
2) get a trans with a 16% lower first gear, or
3) lose 16% weight off the combo, or
4) increase your low-rpm torque by that same 16%.
Let's talk about this option.
Say your pure stock 318 is currently pumping 133psi. The Wallace calculator estimates your V/P to be 110, which is really low. Yur gunna need to bring that up 16%, to 127.6 which will need an increase in compression pressure to 158psi, which, with a stock cam and heads, will require a compression-ratio increase to 10/1. and now, your 2.47 x 3.73=9.21 will take off just fine.

Now, I'll go you one better.
If you had a 10/1 otherwise stock 318, have a gander at that overdrive trans.
The numbers I spit out, suggest that your minimum first roadgear is 9.21, which with the od trans requires a minimum 2.98 rear gear.
Second needs to be around 6.50, which is 3.89 rear gears.
Easy peasy right, just slam some 3.91s in there and call it done right?
Not so fast, your 10/1 318 won't need 3.91s for either First nor Second. and since you already have 3.73s, yur good to go right? and, your 10/1- 318 can easily pull that 54% 1-2 split .
And finally, 65=2200 with 27" tires. yahoo!!
What's not to like?
I'll tell you what's not to like.
32 mph in Second gear is 2485 rpm, and even this 158psi, 10:1, 318, is not gunna pull very hard. The thing is, the vast majority of your city miles are gunna be at 30 to 35 mph. Downshifting into first at 32 mph brings 4600rpm, and you'll only be in it for a second, and then yur outta revs. So then, 3.73s are the wrong gear for this circumstance. the Second roadgear is 1.67 x 3.73= 6.23, which is just too low, IMO, for this combo.
The only solutions for this dilemma are, a higher rear gear, or a bigger engine. This is why I chose a 360, for to work with this specific trans. And I started with 4.30s for 32mph =2860, and 65=2540
The 11/1, 360 instantly annihilates the tires from 2860 in Second gear.
My problem was remembering to ease into overdrive, and I kept blowing them up. After 35 years of banging 4 gears, every once in a while I'd forget.

Now, above, I have been talking mostly about 318s, and mostly about a 10/1 engine. If you have something different, the numbers would need to be slightly adjusted.

Next, I have run every one of those transmissions with every gear from 2.76 to 5.13s; except 3.73 and 4.56; and behind both my Summer engine, the HO367, and my winter-engine, a low-compression 318, and some behind hi-compression 340s.
I'm 72 and have been driving Mopar stick cars for almost the entire time. I know what I liked and what I didn't like. So now we come to, what's the best.

The best trans/rear gear combo, IMHO, is to run the Commando, and strap a GVod on the back of it, and run 3.55s at 10 pounds per cubic inch. You can go one gearsize in either direction, if you want or need a lil more pep, or a lil more fuel economy, or you have a different than 10/1 pounds per cid .
The straight up road gears are ;
10.97-6.82-4.97-3.55-2.77, and 65=2240rpm.
If you already have the 2.47 box,
then I would run it with the 3.73s for ;
9.21-6.60-5.00-3.73-(2.91od); 65=3020 in direct/2355 in od
IMHO, this would make an even better combo than mine, because of the better 3-4 split; and I would have a 2.47 box, except, my 1-2-3 is a touch better, and I never hit the 3-4 at WOT anyway.
If I was "stuck" with a 318, or any low-compression SBM;
the first thing I would do is,
get rid of that low cylinder pressure.
For a streeter, with a manual trans, that nominal 8/1 Scr is a real downer. Whatever you spend on getting the pressure up, will be regained in spades, every time you hit the go-pedal, by the ear-to-ear grins, as the tires beg for mercy.

This goes double for if yur not close to sealevel.

 

[mc707]

my head hurts now lol. Right now I’m running a 318, but it’s got some pep. Probably around 10-1 comp. I have a 408 going in soon.I think I’m just going to run it the way it sits and go from there. I’m thinking maybe it won’t be as bad as what i have been reading. Thank you guys for your knowledge and time!!

 

[AJ/FormS]

my head hurts now lol. Right now I’m running a 318, but it’s got some pep. Probably around 10-1 comp. I have a 408 going in soon.I think I’m just going to run it the way it sits and go from there. I’m thinking maybe it won’t be as bad as what i have been reading. Thank you guys for your knowledge and time!!

If yur going to a 408, on the street, in an A-body, yur not gunna like the close-ratio/3.73 combo for long.
Here is just one of the reasons;
Yur starter gear is 3.73 x 2.47= 9.21,
With an Idle speed that will not like to be much under 800, that means your slowest roadspeed will be 7 mph, in gear, if it will pull itself there without drama. This is about double, of what you need to parade with, so, no parading for you.
And honestly,
the 408 will be ripping thru those close-ratio gears like lightning. Even my 367 went thru those with the tires on fire, way too quickly.
Close-ratio gearing is for either small underpowered engines, like 318s, or for road-racing; in both cases, to keep them on the cam, and pulling hard.
Let us know how it turns out.

 

[65 Cuda 340]

my head hurts now lol.

My head hurts now, too.

 

[AJ/FormS]

com'on guys, it all boils down to one thing, How many footpounds you can bring to the party, and their staying power.
The 408 has both of those in spades.