‘73 dart swinger 3 speed manual trans convert to 4 speed

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nickcimer

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hey all!
I am looking into swapping the original 3 speed manual(floor shifted) transmission out of my 1973 dart swinger special for a 4 speed(a833). I was wondering if there is a specific version of the A833 I will need to find to fit into my A body, or if they all fit universally. The car currently has a late 70s 360 cu. in. Motor. I plan on keeping it small block powered, whether it be in 340 or built 318 flavor(depending on the cash situation). The rearend is currently an 8 1/4 inch open diff. Which I plan on either building up with posi Trac or swapping for and 8 3/4”. And information would be appreciated! Thanks.
 
They will all fit, but shifter mounting bosses are different between platforms A vs B,E,C.
You want an A833 'a body' or 'short tail'
and youll need a 727 yoke unless you end up with those funny mid year ones with a 904 tail shaft. I f you can't find one, you can use the long, or '727 length" e body rearest mounting location with the help of a fabricated plate that would move the shifter into the correct A body location. For instance I couldn't find one at the time and so I use one like in the pic below, dual mounting boss b/e 833. Though I've found 7 or 8 a body 833's since...i don't bother changing it because with it...my cars cross weight ratio is like 49%.

20180328_181427.jpg
 
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MOPAROFFICIAL said:
They will all fit, but shifter mounting bosses are different between platforms A vs B,E,C.
You want an A833 'a body' or 'short tail'
and youll need a 727 yoke unless you end up with those funny mid year ones with a 904 tail shaft. I f you can't find one, you can use the long, or '727 length" e body rearest mounting location with the help of a fabricated plate that would move the shifter into the correct A body location. For instance I couldn't find one at the time and so I use one like in the pic below, dual mounting boss b/e 833. Though I've found 7 or 8 a body 833's since...i don't bother changing it because with it...my cars cross weight ratio is like 49%.

View attachment 1715158577
Click to expand...
MOPAROFFICIAL said:
They will all fit, but shifter mounting bosses are different between platforms A vs B,E,C.
You want an A833 'a body' or 'short tail'
and youll need a 727 yoke unless you end up with those funny mid year ones with a 904 tail shaft. I f you can't find one, you can use the long, or '727 length" e body rearest mounting location with the help of a fabricated plate that would move the shifter into the correct A body location. For instance I couldn't find one at the time and so I use one like in the pic below, dual mounting boss b/e 833. Though I've found 7 or 8 a body 833's since...i don't bother changing it because with it...my cars cross weight ratio is like 49%.

View attachment 1715158577
Click to expand...
Do you by chance have a picture with the fab plates?
 
I really like the 3.09 low model. But AFAIK that ratio only came in the Early As with the trunion drive shaft. So then you have to convert it to a slip-yoke type at extra cost.
Or you buy a burned up overdrive box and a standard mainshaft,and then shove all the early gears in there. Then you end up with a lightweight box,all aluminum, with ratios of 3.09-1.92-1.40-1.00 and splits of .62-.73-.71, and a bunch of junk parts. It weighs about 85 pounds now.

If the 360 is a lo-po, then you also have the overdrive option. And that goes well with your rear-end swap idea. But this trans is not really suited to a high-reving engine. It will be very similar to your A230, but with the added overdrive. It works very nicely with a 3.55 or 3.73. The ratios are 3.09-1.67-1.00-.73od and splits of .54-.60-73 You can see how far apart the gears are by the rather large splits.

Typically a guy would use the standard box with 2.66-1.91-1.39-1.00 with up to 3.91s for a really snappy city combo. But if hiway travel is important, than 3.55s would be the minimum.
So lets see what the roadgears would be with 3.73s, a middle-ground ratio, and the standard box.Multiplying it out I get
9.92-7.12-5.18-3.73 and this is a pretty good combo for a mid-level 360.If the cam is too big in the 360 for it's compression, then the bottom end will be soggy. This is where the 3.09 low would come in at 11.53 for 16% better take off.
So what would be the equivalent rear gear for the od box? Well that depends on where you hinge it.I like a minimum second gear in my 360 of 6.8ish; so that requires a 3.55 gear. Using that as the hinge point, I get 4.10s for the od box. And that will get you roadgears of
12.67-6.85-4.10-2.99od .. now compare that to the earlier standard 4-speed
9.92-7.12-5.18-3.73 or the deep low model
11.53-7.12-5.18-3.73

Notice the od box is lagging 4% in second and 21% in third,but gaining 28% in first over the standard box. Overdrive is strictly a cruiser gear, as I have found them to be easily broken.
Now how does this play out in real life?
Well the 12.67 low gear is more race-oriented, but to get the minimum second gear, you are stuck with it. Second gear is very nice. It will get you about 3000rpm@35mph, and if your 360 is close to stock, it will really peal-out. But if you put a big cam in the stock engine, the bottom will be soft and 6.85 will be a bit of a disappointment. But you are maxed out with the 4.10s on account of the granny low. So it becomes very important to not over-cam the 360. But that 6.85 second will get you 60mph at about 5100, which is why I call it the minimum gear. Hitting Third gear this early, with just 4.10 as your next road- gear will kindof suck. Say you took second out to 5500/66mph Well at the shift into third,the Rs will fall to 3360 and your race is over. This is why I call this a low-performance box. It's only good for two gears, and the 65=2420 is kindof nice, but third gear sucks.
I am very partial to the deep-low box and 3.55s.The roadgears are 10.97-6.82-4.97-3.55... It takes off like the standard box would with 4.12s, so first gear is a dump it and go deal. the 6.82 is a strong second, and third is close behind. With a hi-po engine now, the shift rpm might be say 6400, and the Rs will drop to 4600 NOT to 3360/lol, and she is staying on the pipe! But 65=2870 now,in top-gear, so that doesn't go over very well on long trips. So I got me a GVOD to drop it down to 2240.
Whatever you do; if you want a decent take off with 3.55s say, then stay away from the T/A box, with ratios of 2.47-1.77-1.34-1.00.. This is an excellent spread for it's intended application, but the 8.77 is a fairly soggy gear in anything but a stock 360, or a hi-compression small-cammed 360.
The lesson here is to match the trans to your intended useage. Or
Build the engine powerband to work with the trans.
Happy HotRodding
 
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AJ/FormS said:
I really like the 3.09 low model. But AFAIK that ratio only came in the Early As with the trunion drive shaft. So then you have to convert it to a slip-yoke type at extra cost.
Or you buy a burned up overdrive box and a standard mainshaft,and then shove all the early gears in there. Then you end up with a lightweight box,all aluminum, with ratios of 3.09-1.92-1.40-1.00 and splits of .62-.73-.71, and a bunch of junk parts. It weighs about 85 pounds now.

If the 360 is a lo-po, then you also have the overdrive option. And that goes well with your rear-end swap idea. But this trans is not really suited to a high-reving engine. It will be very similar to your A230, but with the added overdrive. It works very nicely with a 3.55 or 3.73. The ratios are 3.09-1.67-1.00-.73od and splits of .54-.60-73 You can see how far apart the gears are by the rather large splits.

Typically a guy would use the standard box with 2.66-1.91-1.39-1.00 with up to 3.91s for a really snappy city combo. But if hiway travel is important, than 3.55s would be the minimum.
So lets see what the roadgears would be with 3.73s, a middle-ground ratio, and the standard box.Multiplying it out I get
9.92-7.12-5.18-3.73 and this is a pretty good combo for a mid-level 360.If the cam is too big in the 360 for it's compression, then the bottom end will be soggy. This is where the 3.09 low would come in at 11.53 for 16% better take off.
So what would be the equivalent rear gear for the od box? Well that depends on where you hinge it.I like a minimum second gear in my 360 of 6.8ish; so that requires a 3.55 gear. Using that as the hinge point, I get 4.10s for the od box. And that will get you roadgears of
12.67-6.85-4.10-2.99od .. now compare that to the earlier standard 4-speed
9.92-7.12-5.18-3.73 or the deep low model
11.53-7.12-5.18-3.73

Notice the od box is lagging 4% in second and 21% in third,but gaining 28% in first over the standard box. Overdrive is strictly a cruiser gear, as I have found them to be easily broken.
Now how does this play out in real life?
Well the 12.67 low gear is more race-oriented, but to get the minimum second gear, you are stuck with it. Second gear is very nice. It will get you about 3000rpm@35mph, and if your 360 is close to stock, it will really peal-out. But if you put a big cam in the stock engine, the bottom will be soft and 6.85 will be a bit of a disappointment. But you are maxed out with the 4.10s on account of the granny low. So it becomes very important to not over-cam the 360. But that 6.85 second will get you 60mph at about 5100, which is why I call it the minimum gear. Hitting Third gear this early, with just 4.10 as your next road- gear will kindof suck. Say you took second out to 5500/66mph Well at the shift into third,the Rs will fall to 3360 and your race is over. This is why I call this a low-performance box. It's only good for two gears, and the 65=2420 is kindof nice, but third gear sucks.
I am very partial to the deep-low box and 3.55s.The roadgears are 10.97-6.82-4.97-3.55... It takes off like the standard box would with 4.12s, so first gear is a dump it and go deal. the 6.82 is a strong second, and third is close behind. With a hi-po engine now, the shift rpm might be say 6400, and the Rs will drop to 4600 NOT to 3360/lol, and she is staying on the pipe! But 65=2870 now,in top-gear, so that doesn't go over very well on long trips. So I got me a GVOD to drop it down to 2240.
Whatever you do; if you want a decent take off with 3.55s say, then stay away from the T/A box, with ratios of 2.47-1.77-1.34-1.00.. This is an excellent spread for it's intended application, but the 8.77 is a fairly soggy gear in anything but a stock 360, or a hi-compression small-cammed 360.
The lesson here is to match the trans to your intended useage. Or
Build the engine powerband to work with the trans.
Happy HotRodding
Click to expand...
Very informative! Glad I asked! Thanks!
 
64 and 65. (I wouldn't even go there if I were you) @AJ/FormS , don't most 833/od trannys have the same or similar ratios as the 3 speed he already has?
 
nickcimer said:
Would a 63 thru 66 model have a trunion shaft?
Click to expand...
Up to 65 was trunion for sure, 66 I can't recall, 67 was slip yoke but no more 3.09 low.
________________________________________________________________
I got my stuff from Passon Performance; the gear set, his aluminum box and cover, and the M/S. Then I slammed it all together, BEST gearset I've ever had, and I've had them all! Works great with a 230/110 cam and 10.9Scr with aluminum heads, and 3.55s.
Worked just as good with a 223/110 cam, and that one could easily pull 3.23s.
I did not yet have it with my 292/108 cam, but I think it would have been dynomite. As it was that combo liked a starter gear of about 11 or 12, which was 4.30 gear with the standard ratio.
If I would have had the 3.09 with that one, the rear gear coulda been 3.73s.
These were all for hi-perf street duty.
My opinion is tho, to have a second gear that is reved right out with your combo, at about 60/65 mph.
With a 230* cam peaking at about 5300, the shift rpm in my combo is about 5800. With 27" tires, this calls for a second gear road-ratio of 7.53. Working the math in reverse, this calls for one of the following second/differential combos;
B) 1.67x4.51 ,rounds to 4.56s, comes in the Overdrive box
C) 1.77x4.25, rounds to 4.30s, comes in the T/A box
A) 1.92x3.92, rounds to 3.91s, comes in the 2.66/3.09box
If you had a different combo with less power at a lower rpm than my engine makes, then you might choose to sync 60/65 with say 5250rpm, and that would require 5250/5800= .905 as much gear, or 3.55s, with the A combo. See how that works? There's no sense in running much over 3.55s with that combo, because; A) first gear will just go up in smoke, and B) to get to 60/65mph, you will be out of the powerband in second gear, and it will want to be shifted early, and you lose, and C) of these rear gears;which are you gonna want to cruise with?
Again this is for a streeter.

But you could work the formulas backwards from say 62.5 mph. Say you wanted 3.55s to be your maximum rear-gear. What cam would be best for low-ET at 62.5mph? Well 62.5 calls for 5300rpm in 1.92 second gear with a 27" tire, and those 3.55s. So now you just build a motor with as much power as you need to satisfy your personal ET requirement at 5300 rpm. To put a lil more average power down, you might put the powerpeak at 5000 rpm.

But say you had that overdrive trans with a 1.67 second gear. 62.5 now calls for a power peak at 4600, with those 3.55s. And yer gonna need more than a 360 to make a good showing at 4600rpm. See how that Works?

But say you wanted to be even quicker, so you sacrifice hiway mileage and opt for 3.91s. To make this work, the powerpeak now needs to be 5800 with the 1.92 second gear, or 5100 with the 1.67 second/overdrive box.
__________________________________________________
Now,just to piss you off,
my second roadgear is 8.56, which calls for a powerpeak of 6650.lol. I actually don't care about low-ET at 62.5mph.... because...... it's still spinning those crappy 295/50-15 Cooper Cobras......... or the 325/50-15 BFG DragRadials for that matter.
Happy HotRodding

I bet you're wondering about how I get a second gear of 8.56.lol. Well that is actually first over with a GVOD, or 3.55x3.09x.78=8.56 the next ratio I use is 3.55x1.92=6.82. Then 3.55x1.92x.78=5.32,again a split gear, which gets me 93mph @6150,which is what the combo does in the 1/8th mile. Yeah that's waaay past the powerpeak. Did I mention that I don't care? No really I don't. That was a one-time deal. I'm a streeter.
lol.
 
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