340 torque converter question

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moparmark340

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I just bought a 904 tf6 transmission and want to buy a stall converter before I install it. Are all 340s externally balanced ...there is a lot of options...are there any specific converters I have to get..some are transmission specific others list motors. Mark
 
Later 72 and all 73 were external balance cast cranks. If you look at the harmonic balancer you will see an offset counterweight. It even is marked For external balance 340 only.
You need to check what you have. Previous owner could have gone internal balance on a rebuild.
 
Cast crank,external balanced 340 balancer/damper is on the right.
Steel crank internally balanced 340 & all LA 318's is on the left.

A bigger counterweight with no writing, or a recessed, machined out area part way around the outer ring, will be for an LA 360.

If you do find a V-8 904 transmission, look for these variances:

* 1967 and older transmissions used a small snout converter which also had a different spline count. They do not interchange with 1968 & newer converters.

* Lock-up converters started in the late '70's/early '80's. The tip of the trans splines is machined smooth about 3/4". They take their own, special, lock-up converter & don't interchange with "regular" converters.
 

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This is the pic of the transmission....is this a lock up a transmission ? I am installing this on a 71 dodge dart 340 will this transmission work? Does the lock up work merely through the hydraulics? Any help would be appreciated. Thank you for all the help
 

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Yes that is a lockup model and yes it works through hydraulics. You also need a lockup converter. A non lockup converter will not work. That is a V8 trans btw. The term TF6 is somewhat confusing because originally the TF6 was made to only fit a 6 cyl engine. Later they recast the bellhousing on the TF6 to fit a small block V8 but still called it a TF6 which the old timers like me and Kim know as a 6 cyl trans.

If your 71 340 is original it is an internally balanced engine
 
My last and final question is ..sorry for so many questions. . I will need to put a different yoke on my drive shafts right? By any chance do you know what u joint sizes came in most applications in the early 70s unibody?
 
If you are replacing a 727 you will need a 904 yoke. u joint size, just look up a 318 early 70's chrysler with 904 trans.
 
moparmark340 said:
My last and final question is ..sorry for so many questions. . I will need to put a different yoke on my drive shafts right? By any chance do you know what u joint sizes came in most applications in the early 70s unibody?
Click to expand...

If your original trans was a 904, it will fit and you shouldn't have to change anything. If the original was a 727, you will need a longer driveshaft with a matching rear end u-joint and 904 trans yoke because a 904 is shorter than a 727.
 
The trans yoke will use a 7260 u joint on a 904 trans....rear U joint will depend on what the rear end yoke is and what the driveshaft yoke is...

generally mopars use either a 7260 which is the smaller u joint or the 7290 which is the larger u joint...and then there is the 7260/7290 conversion u joint..
 
I bought the car...and they told me they installed the shift kit long story short I am pretty sure it's a broken planetary gear.. I will eventually put a rebuilt trans. But I want to make a couple track passes and see where I am ay et time b4 I add a cam in it and eventually new heads
 
Turbo Action has performance converters for lockup trans. I'm sure other companies also make them.
I just bought one for my street/strip car and it was $650 shipped.
The converter does not have TCC inside. You must use the babbit input bushing that comes with it. Also requires 7/16" bolts.
26 spline, 10" 3200-3400
 
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