Transmission Vacuum Modulator

First let me say thanks for all the help you all have provided. I wouldn't have been able to haev this Maverick to the point I'm at without this board. I have another Transmission Question.....

Any one have a Vacuum Diagram for a 1972 Maverick with a C4 Auto Transmission?? I have the push in Modulator but there is no line to it. I'm trying to figure out where to route the vacuum line to....


Thanks AGAIN,
Dave

 

Mine just runs up to the Intake manifold.

 

Thanks....That's what I suspected...

This makes no sense. The line is gone.... All the vacuum ports on the intake are plugged off. The transmission was shifting fine, but leaking around the gasket. I changed the transmission filter, fluid and gasket then drove it... it was slipping out of gear like the modulator was bad - I went and bought a new modulator before I looked under the car (stupid I know) and when I jacked it up and looked under there - No Vacuum Line..... This one has me floored

 

Hmm, thats strange! Now you got me wondering if mine will shift with the line disconnected.

 

Beats me.... I guess I'm going to get some vacuum hose and hook it up

 

Well I just went and tried it and there was no noticeable diffrence in the way it shifted with both lines completely disconnected. I would just do like you said and run a line from the manifold.

 

The modulator provides opposition for the shift valves, (I.E. when you give it more throttle, it's supposed to hold out a shift longer, to allow you to accelerate,) This is done by the modulator getting less vacuumm when the engine is under load, so with the line unhooked, there's no vacuumm, and the trans thinks the engine is under max load, so it holds out it's shifts. It'll still shift, just as different points....

 

So if I have a manual Valve Body I don't need a Vacuum line??

 

Not for a manual valve body, no. Since you control your own shift points, the modulator valve does nothing but plug the hole, (obviously, you still need the valve in there, but other than that, nothing needs to be hooked to it.)

 

Thanks. I put the new Modulator in tonight - the only thing I can think is there was an air pocket or something. Fluid was reading full (in park & drive) I sat in the car tonight and shifted through the gears. Backed it back and forth in the garage and the fluid then read low. I put in 2 more quarts and now everything is working like new.

Thanks again for all the advice!