Stupid question about manual valve bodies

I'm no guru when it comes to transmissions, but this is something that has been floating around in the back recesses of my mind for awhile and I thought I would ask here to see what the answer is.

I understand what a manual valve body is (and the reverse manual valve body too), it is pretty much what it states...you shift the trans through the gears manually. My question is this, when you use a manual valve body, do you still need a vacuum modulator on the trans, or does the manual valve body eliminate this?

And to add to my stupid question, is it possible to eliminate a vacuum modulator, or is it something there is no way around? Again, just learning stuff, no actual reason for my asking other than to find out how it all works together.

Only asking this out of curiousity, no other reason.

Thanks!
Mike

MOST manual V.B do away with the modulator and run constant line pressure. One exception is the 40-3 transgo kit that converts an auto V.B to manual ,it still requires the modulator to be connected to control the line pressure..

For any auto shifting you do need the modulator connected .

Originally Posted by gregaust

MOST manual V.B do away with the modulator and run constant line pressure.

Thanks! I guess to continue with my curiousity and like I said, I am no guru with transmission (which is why I am asking these questions, to help myself learn)...you wrote that it runs with constant line pressure when using a manual valve body...at the risk of my sounding stupid, how is that constant pressure achieved?

Thanks for putting up with my questions, I tried searching out the info, but pretty much came up with nothing usable.

Thanks again!
Mike

With mods to the pressure regulator valve and pressure boost valve
and by disabling the modulator/throttle pressure circuit . .The manual VB will run usually in the area of 200psi where an auto type VB with modulator is much lower with little load like maybe 80-100 psi depending on VB , and pressure increases then as engine load does by the modulator sensing the vacuum drop/engine load and signals the pressure boost valve.

Cool...thanks for the info!
Mike