65 driveshaft possible upgrade

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85glht

85glht

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65 Plymouth valiant, 340, 904 automatic floor shifter. It has the “ball and trunnion” front joint on the driveshaft. Has anyone had any success in upgrading this type of driveshaft? I would like to keep this transmission as long as I can upgrade the driveshaft. I don’t plan on having big horsepower in this car. Right now the engine is stock with a cam upgrade… “purple shaft” I was told. No idea what that is.
 
This article has the information you need for the driveshaft:
https://www.earlycuda.org/techdocs/ConvertFrontUJoint.pdf
Also be aware that in order to run the early transmission behind your 340, you will need to use a spacer/adapter bushing in your crank flange, since the pocket in the crank that the nose of the convertor fits into changed diameters in 1968, becoming larger than the '67 and earlier versions.
I believe this is the correct one:
Torque Converter Flexplate/Crankshaft Adapter, 1.81" OD x1.55" ID, A904, A727 | eBay
The ball and trunnion, if in good shape, will more than adequately handle your projected 400hp power level. They did just fine behind the early factory race hemis, even with a 4 speed.
 
Professor Fate said:
This article has the information you need for the driveshaft:
https://www.earlycuda.org/techdocs/ConvertFrontUJoint.pdf
Also be aware that in order to run the early transmission behind your 340, you will need to use a spacer/adapter bushing in your crank flange, since the pocket in the crank that the nose of the convertor fits into changed diameters in 1968, becoming larger than the '67 and earlier versions.
I believe this is the correct one:
Torque Converter Flexplate/Crankshaft Adapter, 1.81" OD x1.55" ID, A904, A727 | eBay
The ball and trunnion, if in good shape, will more than adequately handle your projected 400hp power level. They did just fine behind the early factory race hemis, even with a 4 speed.
Click to expand...
That bushing is to put an early small hub transmission in a large hub 68 and later slant 6 or a small hub 273 transmission in a large hub 318,340,360 crank.
 
bcschief said:
That bushing is to put an early small hub transmission in a large hub 68 and later slant 6 or a small hub 273 transmission in a large hub 318,340,360 crank.
Click to expand...
Which is exactly what he's doing. A '65 Valiant with a ball and trunion 904 that's getting a 340. ALL 340s were large pilot cranks, since they were introduced in '68.
Although, if it's a late '72 or a '73 340, he will also need to address the external balance issue when using the early trans., which is neutral balance.
 
First LA engine was 1967, after the demise of the Poly in 1966.
 
Bewy said:
First LA engine was 1967, after the demise of the Poly in 1966.
Click to expand...
No no no... the LA 273 was introduced in 1964, the poly was last used in 1967. At least in North America.
Even you guys had 273 AP6s in... '65, I think.
 
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To clear things up, this is already done. The engine and transmission are together, running and driving. What led me to ask questions are that the shifter cable(s) are leaking (we believe) and before I sink any money into this transmission (new cables, etc.), I want to know if I'm dumping money into a dumpster or if this thing (mainly driveshaft) will live. I had a friend who had good luck with the 904 and I don't plan on big HP numbers. I dropped the trans pan yesterday and the fluid and the internals look very clean. It's just the big leak that started a few weeks after parking the car is what has me concerned. It looked like the fluid was running right down one of the cables. New ones are over $500:(
Not that I wouldn't spend the $$ but I just don't want to do that just to replace the whole thing later on due to a driveshaft that won't serve its purpose.

Thank you all for your inputs and if there is any more info, I'm open to it.:thumbsup:
 
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