75-76 Aluminum 833 4 speed Overdrive trans questions ?
I have two OD833 transmissions behind mildly upgraded 340 engines and have not had any problems with either of them. They are not bushed but came out of slant six 1980s pickup trucks. I am just running street tires so not a great deal of stress is applied and I have never powershifted into OD so no problems there. I do first and second gear burnouts all the time but not powershifting. My form is not as good as it used to be so I let off the gas when I shift these days. I am wondering why bushing the countershaft helps with strength. Is it just a larger surface area pushing against the aluminum because of the bushing. The shaft doesn't turn in the case so there's not rotational wear. Just wondering.
Slanty ods come with the small mainshaft and the A904-sized yoke.
A high pressure 367 like mine (up to 195psi at one time) makes short work of 7260 U-joints. My driveshaft now carries 1350 yokes on both ends, which are finally surviving.
How much pressure is your mildly upgraded 340 making?
My guess is, that with a modest cam, in an early hi-compression 340, then perhaps as much as 160psi. But if the later Low-compression model, then, perhaps as little as 115 psi.
Pressure is torque, the more pressure your engine makes, the more torque it will make.
Torque breaks parts.
If your 340 is still on 7260 U-joints and she is not breaking them, then, my guess is that the pressure is down, or like you say, the street tires are not stressed, and/or, the clutch is comparatively gentle, or you yourself are fairly gentle; I get that. Do not equate low pressure with low power. I am not insulting your engine.
You can install a 292 cam in an 8/1 340 and it will make gobs of power at high rpm. But it may barely spin the tires at a lo-rpm take off. That's the pressure difference.
And yes, the higher pressure will make more power at peak, all things being equal, but at 5500rpm, the difference is not as pronounced as at 2000.