A-833 2.47 1st gear change to 3.09

-
go-fish

go-fish

FABO Gold Member
FABO Gold Member
Joined
May 20, 2010
Messages
3,252
Reaction score
5,260
Location
74801
I am convinced, by reading @AJ/FormS experience and explanation, that I would benefit greatly from having a 3.09 1st gear and possibly a 1964 - 1965 gear set of 3.08, 1.92, 1.40, 1.

First off, I have looked at Passon's website and read his book but I am not quite finding what I need or not understanding. I'll list my current specs, the issues, options, and then desired effect.

1973 340 Duster, low compression 340, A-833, 3.21 (8.25). Numbers matching car so believed to be the stock gearing of 2.47, 1.77, 1.34, 1. The engine is a standard bore, stock piston, LD340, with a SFT 224/224 @.050, .470 lift, manifolds soon to be TTi steps.

The car is slow to get off the line and can't crawl. Its starting gear is 7.9 (2.47x3.21). I had mistakenly been thinking mine was a 2.66 1st gear with a 8.5 starter gear. I thought a jump to 3.09 x 3.21 = 9.9 starter gear would be pretty good. Now I know my '73 has a 2.47 1st the difference kinda makes it all that much more, almost, mandatory. 7.9 to a 9.9!

My cam is great. I love it and I'm not blaming the sluggishness on the cam. I believe this change will allow the cam to serve me in it's peak performance. I currently have a 3.21 SG 8.25 rear which is factory equipment BUT I do have a 8.75 housing coming together with a 2.94 Eaton True Trac diff and a core 3rd member for a 3.23. Switching to 2.94 isn't a huge problem for the payoff as I do intend to drive on multi-day cross country trips BUT I will also be able to put the 3.23 together for normal use and be close to my current 3.21 gear.

I would like to do the transmission gearing change ahead of a rear gear change so I will know how 3.2X feels with a 3.09 1st gear.

Is it possible to convert my VIN stamped case and put 3.08, 1.92, 1.40, 1.00 gears in place of the 1973 OEM gears? Is this limited to swapping 1st? What parts? Cluster Gear ?

So, I like a 3.XX gear for my area, farmland, 45-55 mph flat roads (3rd), 65 mph limit on state highways (4th), driving in parking lots slower would be nice. I like the economy of a 3.21 and 2500 rpm. Now, it does suck going 65 (2600rpm) in the 70-75 Interstate traffic. I am looking forward to using a 2.94 and going 70mph (2550 rpm).

No cam swap, no other cases or 5/6 speeds. I want to keep my VIN stamped case. I do also want to swap to the ball and detent side cover during the change out too. I'll be looking at the hydraulic Malwood setup as I have a disability in my clutch foot.

What do I need to do here? Just 1st gear available or can I convert the whole shebang to the early gear set? Let me know if I left anything out.
 
Last edited:
I would change the rear gear, or figure out why the engine won't pull off the line. Here's an example. In the 70's I swapped a bone stock 71 (high compression) low miles 340 into what was my 70 440-6 RoadRunner. You are talking about a fairly heavy car, the "hemi" 18 spline box with a taller 1st gear, and 3.54 Dana. I had pretty tall rear tires, and it ran about 3000 at near 70 mph. I never had any trouble pulling away from a stop and as I was in the Navy for part of that, I ALWAYS had two heavy tool boxes and other junk in the trunk. And even though it WAS a bit of a clutch slippin' operation, I pulled a trailer with a 70 Cuda on it and full of spare parts, when I got out of the Navy, from San Diego to the N end of Idaho.

Maybe the cam isn't timed optimally? Carb jetting/ ignition curve? Makes a lot of difference

I've always figured the 3.0 first gear is a weak sister. If I remember, the main shaft is smaller
 
3.09 gearset will swap into your cases without any other modifications. I run this gearset in my 72 Demon, with 3.23 axle and 27" tire. Bumpy cam in a very mild 360 SB, and it drives really well. I can easily maneuver the car at idle. I have plans to either put a 2.94 gear in the car or get the tire height up to 28".
 
I think you are about to spend a bunch of money and effort on something that is not only not worth it, but going away from a performance driving experience.

The transmission you have is the closest ratio trans they put in an A Body. It’s a great box with an excellent gear spread. I’d change out the rear gears before doing transmission surgery.

To be honest with you, it sounds like your tune up is **** or your motor is tired. My 273 with 3.23 gears will crawl at idle and fuckin ROAST the tires off the line….and it’s an Automatic car…87,000 original miles on the motor completely stock.
 
67Dart273 said:
I would change the rear gear, or figure out why the engine won't pull off the line.
Click to expand...
Not going there. This isn’t engine diagnosis time. My engine is tuned well and runs well. It’s obvious doing the math that a change to 3.09 will give me more advantage than a 2.47 1st gear. My cam and rear gearing is beautiful for my cruising patterns. Just a discussion about gearing the trans, only.
 
MidnightSwinger said:
I think you are about to spend a bunch of money and effort on something that is not only not worth it, but going away from a performance driving experience.

The transmission you have is the closest ratio trans they put in an A Body. It’s a great box with an excellent gear spread. I’d change out the rear gears before doing transmission surgery.

To be honest with you, it sounds like your tune up is **** or your motor is tired. My 273 with 3.23 gears will crawl at idle and fuckin ROAST the tires off the line….and it’s an Automatic car…87,000 original miles on the motor completely stock.
Click to expand...
Automatic is a completely different animal even with the same 1st gear ratio. My Demon had the 2.47 R in there when I bought the car, and I have no regrets swapping to the 3.09. It drives so much better.
 
It's all in the combo of parts and it depends on what you're comfortable with, I put 8 3/4 in my vehicles and have different ratios of 3rd members to choose from, you would love 3.91's, just let the RPM's sing most of the time and when you want to go on a long trip 2.94's, it only takes 60 minutes to swap 3rd members.
 
Dan Brewer said:
Automatic is a completely different animal even with the same 1st gear ratio. My Demon had the 2.47 R in there when I bought the car, and I have no regrets swapping to the 3.09. It drives so much better.
Click to expand...
I definitely won’t argue with you Dan, but my point was he has some problems if he can’t get an aggressive launch with a 340 and a 4 speed.

I have driven that exact combo(73 A833/3.23) but with a slant six and it would crawl out of first and do burn outs.
 
MidnightSwinger said:
To be honest with you, it sounds like your tune up is **** or your motor is tired.
Click to expand...
This isn’t engine diagnosis. This is in the Manual Trans section.
I apologize for leading two of you to believe I’m trying to cure poor engine performance. It runs very well but letting off the clutch in first it wants to Gallup instead of walk.
Whatever I said about it not performing like I wanted it to at low speeds and acceleration is easily explained in the MATH that I point to. I’m not smart but I’m not a retard either. 3.09 would be an excellent 1st gear over the 2.47 for my situation and seemingly DannBrewer and @AJ/FormS agree.
 
Last edited:
I'm no expert, but pretty sure you should be able to find an early companion flange 4 speed and swap the gears into your case without problem. Might need to swap the bearings, but I doubt it. And I would guess the side cover swap would require different forks, but nothing else (besides the cover).

The 3.09:1/1:1 gear set is functionally the same or close to the same gear splits as the Passon OD setup and people love those.

Pretty sure the '75 318 4 speed cars used a 3.09:1/1:1 gearset, too. So even the factory went that way.
 
moparlvr166 said:
It's all in the combo of parts and it depends on what you're comfortable with, I put 8 3/4 in my vehicles and have different ratios of 3rd members to choose from, you would love 3.91's, just let the RPM's sing most of the time and when you want to go on a long trip 2.94's, it only takes 60 minutes to swap 3rd members.
Click to expand...
Exactly. And for my combo of parts I’m pretty happy with the way it drives just need to tweak it. I am currently putting together a 8-3/4 and have 2.94 3rd waiting to go as soon as I get BBP axles and my 11” drums bought/.put together. Depending on how I like 3.09 1st gear will dictate how what gears I put in my second pumpkin 3.23/3.55).
 
Last edited:
MidnightSwinger said:
I have driven that exact combo(73 A833/3.23) but with a slant six and it would crawl out of first and do burn outs.
Click to expand...
Not trying to be argumentive but earlier you said you drove a 340 with 3.23’s in an auto. This is a manual trans discussion but feel free to give your stall and the gearing in the 904 or 727 or whatever automatic you used so we can compare those oranges to these apples.

You also drove a 73, 833, 3.23. Different car? Weight? Mix match of parts being it had a 3.23 in 1973. Should be a 3.21 so that’s Beggs the question, if it had a rearend swap did it have a 1973 gear set in the 833? Perhaps it was an early 3.09 gear set? Wasn’t the same as my factory 2.47.
With a 2.47 first ands 4.10 rear gear would get a starting gear of 10. A 3.09 and a 3.23 has a starting gear of 9.9. My 2.47 x 3.23 is 7.9.




MidnightSwinger said:
he has some problems if he can’t get an aggressive launch with a 340 and a 4 speed.
Click to expand...
The car does launch well for being geared the way it is. Geared the way it is isn't the best. My definitions of how it accelerates shouldn’t have implied the problem was with the engine.
 
Last edited:
go-fish said:
This isn’t engine diagnosis. This is in the Manual Trans section.
I apologize for leading two of you to believe I’m trying to cure poor engine performance. It runs very well but letting off the clutch in first it wants to Gallup instead of walk.
Whatever I said about it not performing like I wanted it to at low speeds and acceleration is easily explained in the MATH that I point to. I’m not smart but I’m not a retard either. 3.09 would be an excellent 1st gear over the 2.79 for my situation and seemingly DannBrewer and AJ (aka. The Wizard).
Click to expand...
I apologize for trying. I won’t comment on another one of your posts. The next time you want to use the word retard, think about what that word means and who it affects. I’m sure your vocabulary is expansive enough to not slur neurodivergent people when you are trying to make a point.
 
go-fish said:
The car does launch well.
Not trying to be argumentive but earlier you said you drove a 340 with 3.23’s in an auto. This is a manual trans discussion but feel free to give your stall and the gearing in the 904 or 727 or whatever automatic you used so we can compare those oranges to these apples.

You also drove a 73, 833, 3.23. Different car? Weight? Mix match of parts being it had a 3.23 in 1973. Should be a 3.21 so that’s Beggs the question, if it had a rearend swap did it have a 1973 gear set in the 833? Perhaps it was an early 3.09 gear set?




I never said it didn’t launch well and my definitions of how it accelerates shouldn’t have implied the problem was with the engine.
Click to expand...
Your reading comprehension does not lend well to your claim of not being a retard.
 
go-fish said:
Is it possible to convert my VIN stamped case and put 3.08, 1.92, 1.40, 1.00 gears in place of the 1973 OEM gears? Is this limited to swapping 1st? What parts? Cluster Gear ?
Click to expand...

I would find a complete gearset and swap all gears and the cluster. This includes the reverse idler.

When I had my A833OD apart a couple of months ago, I thought about swapping the 1/2 slider with another one I had and after some limited reading decided that the one I had and the spare were potentially different. There are markings, notches in the points of the gears and such, that lead me to believe they were different. Because I couldn't verify the reverse gears and idler would mess fine, I left things alone.

Thus, I would keep everything together. You will have less chance of an issue doing it this way.
 
MidnightSwinger said:
Your reading comprehension does not lend well to your claim of not being a retard.
Click to expand...
Sorry for the language but your intent with your words are basically trying to call me a retard.
You need to understand this. We are talking about a manual. You are bringing up you experiences with automatics which just muddies everything up. Take into account that autos have completely different gearing options and these things called torque converters.
I never once said my engine sucked. It’s great and if you can do MATH you will see that the combo works great for my needs but this one weird trick would make first gear better.
Guys on the internet will always FIRST try to start solving an engine issue and SECOND tell you to give it more rear gear.
We’re not doing that here.
 
the 64 to 66 six cylinder trans has the 3.09 gear set. , it drops in, don't need to change reverse gear either, i had a friend , changed to a 3.09, from a 2.47 gear set, in 1/4 mile it was two tenths quicker, the 340 will pull the split on 1 -2 shift easy. i ran the same in my 340 car, go for it,just food for thought
 
From Passon’s SA Design book book.
Note 7 says these are all interchangeable.
I guess the crux of it all is the 64-65 complete main shaft swappable?
IMG_8880.jpeg

IMG_8881.jpeg
 
go-fish said:
From Passon’s SA Design book book.
Note 7 says these are all interchangeable.
I guess the crux of it all is the 64-65 complete main shaft swappable? View attachment 1716268441
View attachment 1716268442
Click to expand...

Based on that, I guess maybe you only need the input, 2nd and 3rd gear and the cluster.

In regards the the reverse idler, I'm not saying it absolutely has to be swapped. It was only a suggestion to make sure a problem doesn't happen and the trans has to come out again. Makes sense that the reverse idler wouldn't change, but I know the parts trans I have had a different slider/reverse gear than the one that was in my good trans. But both of those were OD trans, and the parts trans was a truck one to boot. So, just a thought.
 
DionR said:
Based on that, I guess maybe you only need the input, 2nd and 3rd gear and the cluster.
Click to expand...
Front bearing is the same and same retainer? What I need is a core to play with until I want to pull my trans.
 
@MidnightSwinger I truly am sorry for the inconsiderate use of the word I used. It seems personal to you and I want to respect the things you think are important.

No hard feelings on my part either. I’m just trying to fine tune my gearing. I’m happy with a 3.2X for the kind of driving I do but that is only 4th gear (1:1). There were three 1st gear options in the 23-spline 833 trans and I have the wimpiest one so I want to change that one aspect. Really just trying to dial the conversation in on this, hence the fact that I placed it in the Manual Trans and Clutch Discussions section.
 
You must log in or register to reply here.
-

Back
Top