Transmission questions

[Mr. Austin]

So i am getting a new oil pan gasket, deeper pan with fines and an oil plug.
Now i am curious seeing how the car is from 69 the modulator. transmission modulator. how hard is it to change out? what does it exactly do? would it be smart to do while focusing on the tranny?

I have heard different things of what it does but they are ball park ideas.

[Rev'n Kevin]

The Vacuum Modulator monitors engine vacuum by a rubber vacuum hose which is connected to the engine. Engine vacuum reacts very accurately to engine load with high vacuum produced when the engine is under light load and diminishing down to zero vacuum when the engine is under a heavy load. The modulator is attached to the outside of the transmission case and has a shaft which passes through the case and attaches to the throttle valve in the valve body. When an engine is under a light load or no load, high vacuum acts on the modulator which moves the throttle valve in one direction to allow the transmission to shift early and soft. As the engine load increases, vacuum is diminished which moves the valve in the other direction causing the transmission to shift later and more firmly.

To replace the transmission vacuum modulator, you need to jack up the front passengers side of the car and support it on a jack stand. Before starting, apply the park brake fully. You will need a rag, an ice cream pail and a 1/4 inch drive rachet, with universal and 12 inches of extensions and a 10 mm socket to remove the modulator hold down clamp bolt which is slightly above the modulator valve.
Remove the Vacuum hose, remove the 10 mm bolt,catch the clamp, place drain pan(ice cream pail) under the modulator to catch tranny fluid if it drips. Wiggle the old leaking unit out of the bore and remove the small diameter shaft from the old unit. Insert the shaft into the new unit and carefully guide the new unit into the bore, wiggling it in all the way. Grab the hold down clamp in your hand, and place it in its position to hold down the modulator, this clamp goes one way and rests on the flange of the modulator to hold it in firmly. Install and tighten the bolt to approximately 15 foot pounds of torque, install the vacuum hose after blowing it out from the top, remove it from the vacuum tree by the brake booster(drivers side)and blow all the tranny fluid out, and if the hose is rubbery from being saturated in fluid, replace the top part which is about a foot long. Road test the vehicle, and if you have an adjustable unit, adjust the shift points to where you would like them by turning the allen screw clockwise or counterclockwise. Good Luck. And don't forget to check the tranny fluid level!