C4 valvebody question

It can be done several ways. All C-4 transbrake & rev manual valve bodies that I'm aware of start out with using the stock upper half (this is where the problems begin). Depending on the year of the valve body, one of the lest expensive ways of making a reverse valve body is to buy the separator plate & lower half, modify your upper half and your done. They sell a casting, plate & pr spring for doing this (its been around since the 60's). Another way is to fill the some of passages in the casting with epoxy or machine in round sections and pound in aluminum doll pins to block some passages, then you have to re machine several passages. Very time consuming, and requires some degree of machining skills (a Bridgeport). Its that or you start with a billet piece of aluminum and make your own lower half. Again, time consuming, and you will need a cnc mill time and cad experience.
The upper half contains the PR valve and the manual lever valve. In order to obtain high line pressure in a C-4, you must use a very strong pr spring. The pr valve is a steel valve in a aluminum housing. (remember, your starting with a USED valve body-that already has some wear) The high pressure spring on the pr valve tends to put side loaded wear into the aluminum casting, thus wearing out the casting. (common problem with saturn's among other)
It boils down to how much free time you have.
 
Thanks for the reply. I was just curious because evidently the vb in mine is a modified stock piece. I think that might be why it shifts so smooth. I will eventuallyget a PA valvebody but for the time being im just going to use the one i have. Im still curious as to why the previous owner decided to do that instead of putting an aftermarket one in it. It was behind a 600+ hp motor for some time. Its not rollerized either. Im surprised it held up for as many years as it did.
 
PA's (along with everybody else's valve body) starts out as a stock piece. PA only makes the lower portion and plate.
Line pressure (you will need a gauge to check it) servo size and direct clutch capacity converter stall axle gear ratio/tire and shift rpm are all factors on shift firmness.
They don't feel like they shift hard if you have a high stall converter or with a lower 3 something gear/tall tire.
 
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