3-speed

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cbig1969

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I have searched the internet like a mad man and cannot even find general information on the 3-speed manual transmission 1972 340 Duster that I own.

What's the purpose of having a 3 and 4 speed of the same year and model.

Are 3 speeds rare? They must be rare.

Can someone explain to me the differences besides the obvious ones? There has to be a reason for this. What are the advantages of having one over the other? Let me say this, with my 3-speed, once I'm in the 3rd and final gear the car feels like it needs go up yet another gear.

To anyone who can fill me in on this, I appreciate it.
 
It was an insurance thing. Insurance companies were targeting V8 4 speed cars for big increases in 1972, so ma made a bunch of V8 3 speed manual cars to help customers skirt the rules a bit.
 
I guess I am not up to speed on what 3 speed changes might have been made from 60's models to the '72 that you have, but I can say that those early 3 speeds were WEAK. I don't know how many low gears I broke before I switched to a torqueflite. you could break the low gear slider without blinking an eye. Once I broke one when I clutched to go over a speed bump, when I let it out to creep up on it with the rear wheels it sheered the teeth off like corn off a cob.
 
Here's my 2 centavos.
I have owned and driven both for several miles in different cars over several years. (Mostly '69 to '76 A-Bodies)
The 4 speed is a stronger transmission for sure, but the 3 speed that you have isn't all that bad unless you really abuse it.
The transmissions in the slant 6 ''three in the tree'' cars are the ones that are fairly weak.
The three speed that you have is a 1:1 ratio in 3rd gear just like the 4 speed is 1:1 in 4th. If you feel that it needs an extra gear, it is more the product of your rear gear ratio and tire size. Back in the days when your car was new, that's just the way it was and you just lived with it.
Driving experience of both is pretty good.
The 3 speed has a bigger spread between gears by design, and the 4 speed is a closer ratio between gears of course.
I think the whole idea makes sense that the 4 speed would have less R.P.M. drop between the gears, and that would make it better for racing as well.
For general driving, the 3 speed is just fine, with the added bonus of less gear changes to get you where you want to go with a little less effort.
Also, i do buy the reasoning behind tricking the insurance companies by offering the 3 speed over a 4 speed, but it also was to save money and lower the price of the car as well. They offered the 3 speed floor shift as the standard transmission for '70 Road Runners with the H.P. 383, so i doubt it was that weak, and it's the same basic transmission that came in the 340 cars.
My old '71 Demon had a ''3 by the knee'' transmission in it and it took a LOT of abuse without breaking.
I thought it was a great package, and was fun to drive.
BTW, your car is fairly rare, they made 2,401 of them, and the 4 speeds were slightly more at 2,871. Automatics were 8,530.
 
I have had several 3 speed cars the first was a red 70 Road Runner that was a 383 3speed on the floor it was the base model not a single option and with the stock 14" tires it felt like it could use at least one more gear but being a teenager and not knowing any better I broke it and replaced it with a 4 speed. the second was a 73 Duster with a 6 and the 3 speed on the floor it was a fun car from what I can remember I think I gave that car to a friend that needed wheels and the third was a Hang Ten Duster with a 318 and the 3 on the floor that one rusted to dust I think I got 50.00 for it at the junk yard while the 3 speeds aren't seen much any more I think there were lots of them. I know where there is a 70 Barracuda in sublime green that is a 6 cylinder 3 speed factory A/C P/S P/B car that has been pasted from one family member to another since it was new so they are still out there.
 
autopar3000 said:
It was an insurance thing. Insurance companies were targeting V8 4 speed cars for big increases in 1972, so ma made a bunch of V8 3 speed manual cars to help customers skirt the rules a bit.
Click to expand...

That may have been part of it, but the truth is a 3 speed is cheaper to manufacture. "You youngsters" have to remember than 4 speed gearboxes were a rare, expensive option at one time. EG there were VERY few 57 Chevs with factory 4 speeds

Dr dan said:
early 3 speeds were WEAK. .
Click to expand...

Well it's all relative. Chev wasn't any better. When I went into the US Navy in the spring of 68 I had TWELVE busted Chev 1st - rev sliders in the trunk of my parts car. The newer Mopar 3 speed was much improved, and stronger.........syncro into 1st gear.

At the time, I had gotten a 60 Falcoon. Those things had the tiny, 144 cube, "85 hp" six, and the 3 speeds in those were truely miniscule.

But / so keep in mind that when these 3 speeds were "in vogue" most cars did not HAVE all that much hp and torque.
 
I appreciate the feedback guys. I was 13 when my Dad taught me how to drive on this particular car and drove it for a while regularly when I was 16 (I'm 46 now) and of course never noticed any difference. Didn't drive it again after that until I was 43 and after having owned a slew of 5-speed 4 and 6 cylinders not to mention having driven 10 speed semi's. Needless to say, now I see the difference.

Don't get me wrong, I love this ride. It is a super fun drive! Being that it is all factory original adds to its uniqueness.
 
The three speed that would have come in your car is the A230 heavy duty three speed. It is about the same size and weight as an 833 four speed. In other words, it's BIG, HEAVY and STRONG.

They do not compare in any way, shape, form or fashion to the earlier six cylinder only three speed transmissions. The A230 is a strong BEEOTCH. Lots of drag racers used them. They are hard to break.

...and no, they are not rare. What happened through time is dumbasses swapped four speeds for them and scrapped them. They are fine transmissions.
 
to say all three speeds are weak is quite an inexperienced generalization.

there are a few different three speed models that were made.

The a-745 is a weak transmission because it was intended for very light duty and was operated as a column shift unit only. It is easily recognized as a top loader.

The a-230 is a much better unit and it was made by new process which is same manufacturer of our beloved 4 speed. It came in fully synchronized heavy duty versions and non- synch versions for slant sixes and/or light duty. By 1972 you are going to have a fully synchronized a-230 that is going to be more than capable of holding up in the application.

The a-230 is recognizable because its a side loader and basically looks like a smaller version of the 833. It also has provisions on the tail shaft for a floor mounted shifter.

Granted a 4 speed has its advantages in performance with closer gear ratios, but the three speed is also a good unit and will serve its purpose.

Three speeds helped with insurance rates as mentioned above. There are even Mr. Norms cars in existence with the a-230 three speed in place.
 
RustyRatRod said:
The three speed that would have come in your car is the A230 heavy duty three speed. It is about the same size and weight as an 833 four speed. In other words, it;s BIG, HEAVY and STRONG.

They do not compare in any way, shape, form or fashion to the earlier six cylinder only three speed transmissions. The A230 is a strong BEEOTCH. Lots of drag racers used them. They are hard to break.

...and no, they are not rare. What happened through time is dumbasses swapped four speeds for them and scrapped them. They are fine transmissions.
Click to expand...

yea ...I took too long typing .....but ^^^ this^^^
 
^^^
HAHAHAHAHAHA,

Laughing at Myself RRR, ol tired memory....

The 'sheitbox' A230 pioneered 'compression loaded' ball bearings on the input, output,
& countershaft (front & rear),

If in error, please correct Sir.

Thx!!
 
mech1nxh said:
The 'sheitbox' A230 pioneered 'compression loaded' ball bearings on the input, output,
& countershaft (front & rear)
Click to expand...

Not sure what this means..........

The 833 4 speed had roller needle bearings in the counter gear, and those were not particularly troublesome

Most gearboxes I'm aware of used ball bearings in the front and for the mainshaft, including 3, 4 speeds. Some were larger and heavier, some not. "What was special" about these again?
 
67Dart273 said:
Not sure what this means..........

The 833 4 speed had roller needle bearings in the counter gear, and those were not particularly troublesome

Most gearboxes I'm aware of used ball bearings in the front and for the mainshaft, including 3, 4 speeds. Some were larger and heavier, some not. "What was special" about these again?
Click to expand...

First, This is not An 833 discussion... or an electronics debate...

Second, A230 'compression loaded' bearings were engineered By Ma Mopar...

Larger outer race, smaller inner race, case hardened to .003 = more 'balls' =

Of course we could get off an some sort of tangential discussion on tapered
bearings.

Back on topic,
I humbly await Mr Robs input .
 
RustyRatRod said:
The three speed that would have come in your car is the A230 heavy duty three speed. It is about the same size and weight as an 833 four speed. In other words, it's BIG, HEAVY and STRONG.

They do not compare in any way, shape, form or fashion to the earlier six cylinder only three speed transmissions. The A230 is a strong BEEOTCH. Lots of drag racers used them. They are hard to break.

...and no, they are not rare. What happened through time is dumbasses swapped four speeds for them and scrapped them. They are fine transmissions.
Click to expand...

I'm one of those dumbasses, but I didn't scrap mine. It's sitting inside a cabinet for "just in case".
 
Had the A-230 behind a slant in my 71 Demon and it lived behind a warm 383 as well. I also had a 71 Road Runner with the same 3 speed that lived a long time....
 
A230 are pretty strong, bought a complete set up out of a junkyard 340 years ago, paid $50 for everything, petals, linkage, tranny, shifter and 8.75, took everything out but the rear.
After about 3 years, the only issue the trans had was you had to hold the sifter in 2nd gear while decelerating down a hill.
Beat the crap out of that transmission, after a couple of years took it out, and sold it to a round track racer.
 
They work well in the applications that they were designed for. Namely torquey, relatively low rpm, and wide powerbands. If you had a small engine with a narrow powerband, a 3-speed is a bit of a handicap, unless it's pulling a light load, like an early A.
I rebuilt probably hundreds of those, back in the late 70s. They were light years better than their predecessors.
 
mech1nxh said:
First, This is not An 833 discussion... or an electronics debate...

Second, A230 'compression loaded' bearings were engineered By Ma Mopar...

Larger outer race, smaller inner race, case hardened to .003 = more 'balls' =

Of course we could get off an some sort of tangential discussion on tapered
bearings.

Back on topic,
I humbly await Mr Robs input .
Click to expand...



I was only comparing the cluster bearings to the 833 that is to say, they are what they are, and don't seem to give trouble.

WTF does it mean "not electronics." I don't remember saying (let me check...........nope I didn't) say a thing about electronics. So what is that supposed to mean

MY POINT is that regardless of what Ma used for bearings, I'm not sure this was such an important step, that is, something the industry copied because it was so good?

In other words "I don't get your point." There are many types of bearings. Some good, some better. Some were under--engineered and some were not. What I'm trying to find out is "what was supposed to be so good and so special" about these bearings?
 
Yeah the compression loaded as I understand it is just another term for a tapered roller OR another bearing that needs some preload.

Correct me Norm sir if I have interpreted that incorrectly. I think you are correct about that, though.
 
JoesEdge said:
I'm one of those dumbasses, but I didn't scrap mine. It's sitting inside a cabinet for "just in case".
Click to expand...

No, you didn't scrap it so you didn't complete the dumbass initiation.
 
mech1 said:
Larger outer race, smaller inner race, case hardened to .003 = more 'balls' =
Click to expand...
&... wait for it... die stamped steel 'seperators' with steel rivets to hold everything
in alignment.
Succinct enough 67dart273 :D??? if I can be of further help I will gladly chime in.
Thx!!

P.s, Robster, 'compression loaded' bearings = more ball bearings in the enlarged circumference
between outer & inner 'races' with the same 'tumbled case hardening' on the 'balls'---
Tapered Roller bearings(roller, not ball) can be 'adjusted' ...compression loaded ball bearings
are of 'fixed' parameters...& actually pressed together--- 'compression loaded'--- = cheap !!!

...And 90 % of the time a sealed bearing--- Not splash or force fed lubricant dependent.
(with the advent of synthetic lubricants & seal material )


Apologies Honored Posters, got off on a tangent :iconbigg:
 
Like this?
 

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Nope, that's a roller design... tapered roller brngs refer to the angle between
the inner & outer race, NOT THE ROLLER... (another topic for another time :iconbigg:)
More like this--- 20'th century 'rivets' & sealed faces excluded :D
View attachment 1714850638
 
Oh, ok. I know whatchyer talkin about now. lol
 
So would the Greene rear axle bearings be considered compression loaded ball bearings?
 
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