I am putting a street friendly, mildly built 340 in my 76 RR which was originally a 318 4 speed w/OD. I can put either the regular A-body A833 in or I can put a A833OD back in it. Which do you think would be more reliable and fun? I will be using this car as a fun cruiser.
Which is Better A833 or A833OD
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kkritsilas
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If you are going to be doing any long distance driving, the A833 OD. If it is just local/in town/city driving, probably the non-OD will be more fun. I don't know anything regarding the reliability between the two versions, but a mild 340 shouldn't preset a problem to either transmission, assuming that both are in good shape.
aspen77rt
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My pick is the OD if your not going to track the car. You can run better gearing and cruise like a dream for a street car.
AJ/FormS
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If you like spirited driving, the O/D unit is out! And here's why;The ratios are too far apart. The ratios are 3.09-1.67-1.00-.73.
-To run the 3.09low, 3.55 is about the deepest street gear you would want to use. Why? because 3.09 x 3.55 =10.97. This is a pretty deep starter gear. It is equal to 10.97/2.66 =4.12 rear with the regular M/T. Ok, so that sounds good,right? Let's look at the cruise gear; 3.55 x .73 =2.59.To run a 2.59 with 26inch tires and going 65mph, this makes; (65 x 1056 3.55 x.73)/26 x 3.1416 = 2177rpm. Sounds good right? Well, to run 2177 efficiently,the 340 will need to be cammed on the small side, or it may not get the type of fuel mileage you are hoping for. But not too bad,so far.
-Now lets look at the percent spits;54-60-73.This shows that at whatever you rev the engine to,the Rs will fall to those amounts in the next higher gear.
-So,let's look at at the 1-2 shift.If you wind your short-stroked 340 up to 6200 in first, the Rs will fall to 6200 x .54 =3348. Does your 340 have torque at 3348? Um, not much. Your power band will need to be 6200 less 3348 = 2852. Knowing that,the rpm of peak power will need to be centered between those two numbers or 4774. To make a good pull with the power peak at 4774, would take a small cam.But the small cam will be out of steam long before 6200.Pulling with a bigger cam will ask the 340 to pull from a part in the powerband that is pretty soft, and even the 3.55s will not help her.
-Lets look at second gear.Again reving to 6200, the Rs will drop to 60% this time, so 3720. Well that's a little better. The powerband is now 6200 less 3720 =2480, and the power peak thus 4960. Again this would be a smaller cam.
Ok,so that O/D is not the best idea for drag racing. But what about in regular driving?
Well,in relaxed driving, I like to shift at about 2800 with my 360,so the 1-2 shift will drop the Rs to 1512(20mph). So has your 340 got torque down there? Not so much,eh?So now you are doing 20mph in second at 1512 mph. And you will be pulling second gear to cruise around 35mph.That is a very long pull to 2682rpm(35mph). If your timing isn't just right the engine will be rattling all the way.
-Next, think about stomping the gas at 35mph. Well at 2682 in second, you will be going no where fast. So you will have to downshift into first. Now the engine will be doing 4963rpm.This is not gonna fool anybody.If you have the small cam matched to this tranny, you will be looking at shifting at something like a 268cam, you will be needing to wind it out to 6200ish(44mph). And then she drops into second at 3348rpm, which she will have to pull to the speed limit.........rra-therr slooowly.
-So by now you probably realize that this tranny was designed for an engine with a limited rpm band and a lot of torque. They work pretty good with a 225, or a teener, or even a very small cammed 360. But if you are gonna buzz to 5500plus rpm, you don't want this tranny.
-So here are the ratios for the non-O/D boxes. See if you can figure out which one best fits your intended useage.
The early box.....3.09-1.92-1.40-1.00 and %splits of 62-73-71
The regular box; 2.66-1.92-1.40-1.00 and %spits of 72-73-71
Trans Am box.....2.47-1.77-1.34-1.00 and %spits of 72-76-75
Compare O/D at 3.09-1.67-1.00-.73 and...%spits of 54-60-73
Each of these will require a different rearend to get a good starter gear between 10/1 and 11/1. Waitaminit;where did I come up with that starter gear? Experience. More than 11/1 makes the 1-2 shift come to early for me. Less than 10/1 makes getting off the line,with a big cam, a bit tricky. By 9/1 it's a struggle.
-Choosing wrongly will make hiway cruising a chore.
I have driven them all, and with many different rears,and My favorite for a streeter,is the early box with 3.55s,or,if you spend significant time on the freeway,then 3.23s.
-If you already have a 2.66box, I would slam that baby in there, and go have some F-U-N.You might need more than 3.55s tho. Do the math. Get the Rs in second gear to a meaty part of the torque curve,at your chosen cruise speed,and you will be grinning.
Here is the formula; (mphx 1056x Rix R2)/(TDx pi) =RPM
R1 is rear-gear,R2 is tranny gear,TD is tire diameter,pi is 3.1416,x is multiply
-Example; (35mphx 1056x 3.55x 1.92)/(26x 3.1416) =3084rpm
340 got torque at 3084? Not so much, but; A lot more than at 2682 with the O/D! Hmm what about ...........
Your turn
-To run the 3.09low, 3.55 is about the deepest street gear you would want to use. Why? because 3.09 x 3.55 =10.97. This is a pretty deep starter gear. It is equal to 10.97/2.66 =4.12 rear with the regular M/T. Ok, so that sounds good,right? Let's look at the cruise gear; 3.55 x .73 =2.59.To run a 2.59 with 26inch tires and going 65mph, this makes; (65 x 1056 3.55 x.73)/26 x 3.1416 = 2177rpm. Sounds good right? Well, to run 2177 efficiently,the 340 will need to be cammed on the small side, or it may not get the type of fuel mileage you are hoping for. But not too bad,so far.
-Now lets look at the percent spits;54-60-73.This shows that at whatever you rev the engine to,the Rs will fall to those amounts in the next higher gear.
-So,let's look at at the 1-2 shift.If you wind your short-stroked 340 up to 6200 in first, the Rs will fall to 6200 x .54 =3348. Does your 340 have torque at 3348? Um, not much. Your power band will need to be 6200 less 3348 = 2852. Knowing that,the rpm of peak power will need to be centered between those two numbers or 4774. To make a good pull with the power peak at 4774, would take a small cam.But the small cam will be out of steam long before 6200.Pulling with a bigger cam will ask the 340 to pull from a part in the powerband that is pretty soft, and even the 3.55s will not help her.
-Lets look at second gear.Again reving to 6200, the Rs will drop to 60% this time, so 3720. Well that's a little better. The powerband is now 6200 less 3720 =2480, and the power peak thus 4960. Again this would be a smaller cam.
Ok,so that O/D is not the best idea for drag racing. But what about in regular driving?
Well,in relaxed driving, I like to shift at about 2800 with my 360,so the 1-2 shift will drop the Rs to 1512(20mph). So has your 340 got torque down there? Not so much,eh?So now you are doing 20mph in second at 1512 mph. And you will be pulling second gear to cruise around 35mph.That is a very long pull to 2682rpm(35mph). If your timing isn't just right the engine will be rattling all the way.
-Next, think about stomping the gas at 35mph. Well at 2682 in second, you will be going no where fast. So you will have to downshift into first. Now the engine will be doing 4963rpm.This is not gonna fool anybody.If you have the small cam matched to this tranny, you will be looking at shifting at something like a 268cam, you will be needing to wind it out to 6200ish(44mph). And then she drops into second at 3348rpm, which she will have to pull to the speed limit.........rra-therr slooowly.
-So by now you probably realize that this tranny was designed for an engine with a limited rpm band and a lot of torque. They work pretty good with a 225, or a teener, or even a very small cammed 360. But if you are gonna buzz to 5500plus rpm, you don't want this tranny.
-So here are the ratios for the non-O/D boxes. See if you can figure out which one best fits your intended useage.
The early box.....3.09-1.92-1.40-1.00 and %splits of 62-73-71
The regular box; 2.66-1.92-1.40-1.00 and %spits of 72-73-71
Trans Am box.....2.47-1.77-1.34-1.00 and %spits of 72-76-75
Compare O/D at 3.09-1.67-1.00-.73 and...%spits of 54-60-73
Each of these will require a different rearend to get a good starter gear between 10/1 and 11/1. Waitaminit;where did I come up with that starter gear? Experience. More than 11/1 makes the 1-2 shift come to early for me. Less than 10/1 makes getting off the line,with a big cam, a bit tricky. By 9/1 it's a struggle.
-Choosing wrongly will make hiway cruising a chore.
I have driven them all, and with many different rears,and My favorite for a streeter,is the early box with 3.55s,or,if you spend significant time on the freeway,then 3.23s.
-If you already have a 2.66box, I would slam that baby in there, and go have some F-U-N.You might need more than 3.55s tho. Do the math. Get the Rs in second gear to a meaty part of the torque curve,at your chosen cruise speed,and you will be grinning.
Here is the formula; (mphx 1056x Rix R2)/(TDx pi) =RPM
R1 is rear-gear,R2 is tranny gear,TD is tire diameter,pi is 3.1416,x is multiply
-Example; (35mphx 1056x 3.55x 1.92)/(26x 3.1416) =3084rpm
340 got torque at 3084? Not so much, but; A lot more than at 2682 with the O/D! Hmm what about ...........
Your turn
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Justwondering
Well-Known Member
AJ/FormS ...
You pack in a lot of good information for a new guy to the forum.
Hope you stick around and enjoy the neighborhood!
Thank you for taking time to share..
You pack in a lot of good information for a new guy to the forum.
Hope you stick around and enjoy the neighborhood!
Thank you for taking time to share..
Jack Meoff
Mopar Maniac
My head hurts now. 
AJ/FormS
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You can catch me me on FABO
So, if you've been banging on the calculator keys;here's why I like the early box;
3.09-1.92-1.40-1.00, and the 3.23s
#1) 3.09 x 3.23 =9.98; a great starter gear for a 360, and pretty good for anything else, with a street-friendly cam.
#2) 3.23 final drive.65mph is about 2600rpm
#3) Second gear stomp; 35mph is about 2700Rs. Not so high as to be aggravating to everybody around you, but, with that street-friendly cam,street-friendly rear suspension, and street 15s, they will light up when the DP says go-time!
#4) the splits; these are tight enough to make a powerband of about 1700rpm with a cam that powerpeaks at about 5500.So you will be outshifting at about 6200, to drop in at about 4500. Saweeeet! 4500 is close to where that cam will be putting out max torque, and 6200 will be about where the combo maxs out.What could be finer than that?
-And the only difference between the 3.09 box and the 2.66 box is that very first gear. So if you are "stuck" with a 2.66 box, you might have to rev it a little higher to get off the line,briskly.
Of course 3.55s would put the punch back into it.Which would put 10% more Rs into the second gear stomp;oh yeah! 35mph will now be a tic under 3000; perfect for a 340.The only downside is the Hiway Rs also rise that same 10%, to 2860@65;still doable.
So, if you've been banging on the calculator keys;here's why I like the early box;
3.09-1.92-1.40-1.00, and the 3.23s
#1) 3.09 x 3.23 =9.98; a great starter gear for a 360, and pretty good for anything else, with a street-friendly cam.
#2) 3.23 final drive.65mph is about 2600rpm
#3) Second gear stomp; 35mph is about 2700Rs. Not so high as to be aggravating to everybody around you, but, with that street-friendly cam,street-friendly rear suspension, and street 15s, they will light up when the DP says go-time!
#4) the splits; these are tight enough to make a powerband of about 1700rpm with a cam that powerpeaks at about 5500.So you will be outshifting at about 6200, to drop in at about 4500. Saweeeet! 4500 is close to where that cam will be putting out max torque, and 6200 will be about where the combo maxs out.What could be finer than that?
-And the only difference between the 3.09 box and the 2.66 box is that very first gear. So if you are "stuck" with a 2.66 box, you might have to rev it a little higher to get off the line,briskly.
Of course 3.55s would put the punch back into it.Which would put 10% more Rs into the second gear stomp;oh yeah! 35mph will now be a tic under 3000; perfect for a 340.The only downside is the Hiway Rs also rise that same 10%, to 2860@65;still doable.
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aspen77rt
Well-Known Member
Not as hard as it seems. You just need a rpm calculator like Engine RPM Calculator
Essential how I approached the gearing in the Mustang on the AOD/T-5z swap (auto to Manual) which is a street car.
-Mild EFI 302/T-5z/4.10/26" tire
2500rpm shift/lazy street driving
1st 2.95 2657rpm 17mph (12.09) *to quick a shift from 1st to 2nd
2nd 1.94 2570rpm 25mph
3rd 1.34 2485rpm 35mph
4th 1.00 2649rpm 50mph
5th .75 2583rpm 65mph *rpm still high enough to lazily pass in 5th
Cruising at 60 mph in 5th turns 2400rpm. Dropping (for passing) to 4th turns 3200rpm well into the lower end of the torque curve for the motor.
All in all, it works. But, the 4.10's are obnoxious on the 1-2 shift. I may drop to 3.55 if they annoy me too much.
T-5z close ratio trans split
Online Conversion - Percent Calculator
65%(1-2)/69%(2-3)/74%(3-4)/75%(4-5)
Essential how I approached the gearing in the Mustang on the AOD/T-5z swap (auto to Manual) which is a street car.
-Mild EFI 302/T-5z/4.10/26" tire
2500rpm shift/lazy street driving
1st 2.95 2657rpm 17mph (12.09) *to quick a shift from 1st to 2nd
2nd 1.94 2570rpm 25mph
3rd 1.34 2485rpm 35mph
4th 1.00 2649rpm 50mph
5th .75 2583rpm 65mph *rpm still high enough to lazily pass in 5th
Cruising at 60 mph in 5th turns 2400rpm. Dropping (for passing) to 4th turns 3200rpm well into the lower end of the torque curve for the motor.
All in all, it works. But, the 4.10's are obnoxious on the 1-2 shift. I may drop to 3.55 if they annoy me too much.
T-5z close ratio trans split
Online Conversion - Percent Calculator
65%(1-2)/69%(2-3)/74%(3-4)/75%(4-5)
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AJ/FormS
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I guess the O/D could work with the 340, if you put a 2bb type cam into it; essentially making it a big-bore teener with a 4bbl.
I did something like that back in 75 or so. That worked pretty good in a 65 V100 wagon,with a 904
She was a real nice cruiser.
If you don't mind giving up a few ponies at 5000, to gain a bunch of torque from idle to 3000, that might work really good with the O/D box!
I like that idea. .....note to self...tiny-cam,340Belvidere cruiser, with od;yup kick the teener to the curb,"MoPar-formance"
I did something like that back in 75 or so. That worked pretty good in a 65 V100 wagon,with a 904
She was a real nice cruiser.
If you don't mind giving up a few ponies at 5000, to gain a bunch of torque from idle to 3000, that might work really good with the O/D box!
I like that idea. .....note to self...tiny-cam,340Belvidere cruiser, with od;yup kick the teener to the curb,"MoPar-formance"
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