Vacuum modulator c4 tranny this one does not have a bracket?

Asked by Jul 06, 2013 at 06:49 AM

Question type: Maintenance & Repair

How do i remove it ...
What part of the body of
the modulator . Is the
bolt in front of it part of
the modulator or is a
seperatte piece... They
said this was easy but
quite difficult at this point
. Need more specific
details on exactly how to
remove it. Thanks

22 Answers


What if yours is suppose to have a bracket holding it and the bracket is just missing? If so you should be able to grab modulator and with a wiggle or two just pull it out of its resting place. Just a thought. These things are normally real easy to remove.

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From looking at pictures of the one for the c4 it should have a bracket. If you don't have a bracket it is probably just missing. Grab that thing and give it a tug and wiggle or two it should pop right out.

1 people found this helpful.

I think mines a screw on one ? So pulling does not wrk unless it's screwed off.. Any other suggestions


I have sent word to a friend who knows these trucks in and out. Hopefully he will be contacting you shortly. Sorry I could not be of more help.

Hi fellas. The C4 automatic has a vacuum modulator that senses change in the engine's vacuum due to throttle position and load changes. With these changes the modulator adjusts the shift timing of the transmission according to the demand of the engine. Fabi: does yours look like this? and are you wanting to change it out? They can be adjusted ya know. I can tell you how to to bracket by the way...

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Best Answer Mark helpful

it works like this inside

6 people found this helpful.

and dandy thanks for picking up for me on that transmission filter, I have not been home the last few hours...that was a learning thing for me

1 people found this helpful.

And in comes my friend to the rescue. Good morning or let's say good evening DavidH25

2 people found this helpful.

I had found one that looked like that with the spot for a wrench to fit onto it but I also found one listed for the c4 trans that did not have the spot for a wrench it just pushed in with a bracket that held it on. Sure glad you dropped in to help us with this one.

Hey, on the left coast it's still morning....anyway it screws in and has an 'O' ring. It's not like I can go out and look at my truck, I have a 4 speed...but fabi it could be one of two types. If it does indeed have a bracket it will pull out, or this type screws in...may I ask what the issue is? Like I say they can be adjusted..shifting too hard? Like this one?

6 people found this helpful.

Or it might be like this..

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Those are the two I was looking at. Thanks

Ford used the same kind, those two, until 1981 and 1982 and after are way different ...and I said that bass ackward the one that screws in does not have the 'O' ring I had 1882.....I guess they would be different in 1882 eh?


He has three questions going at the same time for this issue. I feel pretty confident that I was on the right page with my answers. Covered the screw In type on one of them and the push in on the other. Just wish this iPad would allow me to copy pictures off of other sites. That would help.

You were. Or are, going in the right direction. I looked at fabis activity and he has 4 going actually over the last 2 days...sorry fabi i know it's not polite to talk about you in 3rd person

Ok...I will do this.....might help. May not have to even take it out. Depending on what is going on...? . Set the shifter in the "Park" Raise the vehicle on the passenger side using a floor jack. Put a jack stand under a solid section of the frame. Find the C4 transmission modulator at the rear of the transmission. It has a small rubber vacuum hose that connects to it. The other end of the hose is attached to a steel tube that rises up to the engine. Remove the rubber hose from the modulator nipple by pulling it straight back by hand. Insert a narrow shank flat head screwdriver into the nipple until it seats into the slot of the adjustment screw. Right in where the vacuum hose came off. Turn the modulator adjustment screw in a clockwise direction with the screwdriver to firm up and delay the up-shift of the transmission. Do not adjust the screw more than four turns in either direction. Turn the adjustment screw in a counterclockwise direction to speed up and soften the up-shift. Adjust the modulator screw one turn at a time. Replace the vacuum hose onto the modulator nipple until it is fully seated

4 people found this helpful.

Ok I went to the other posts and Jim has a good answer.....about the bracket kind. Jim certainly knows what he is talking about, I know that for sure. The only thing is I don't know if Jim knew it's a 1977 or not. And I finally found out what the issue is....wont shift at all. still could be the modulator, or be sure to check the vacuum SOURCE to it...the other end

2 people found this helpful.

Thank u guys I fond out that I have a mustang tranny on m truck... And finally after the third day I screwed it out that was lots of work. Pictures are very helpful. So after we remove it we put new one and do we do any adjustments . Clock wise or counter clowise.

Don't adjust anything if if shifts as it should. See what I wrote..if it is shifting too hard, and seems like it waits too long to shift, turn the screw inside the nipple 1 360 counter~ clockwise turn to soften the shift and at a lower rpm. 1 turn clockwise if you want a harder shift and delayed to a higher rpm, and do make sure about the other end of the hose, that there is full intake manifold vacuum available to the modulator.

2 people found this helpful.

Is it better we test drive on street or fwy?


Hello. Can someone give me a hand please. I have a 1977 Ford Thunderbird and im looking at the transmission shift valve .. I need to know what vacuum i need to hook it to. Constant or intermittent????

6 people found this helpful.

Hello,can someone give me a hand please.I have 1967 mercury cougar 289 cubic inch 4.7L c4 automatic transmission and when I start the engine in parking the car wants go forward and when I select reverse the car also goes forward and in neutral the same thing

2 people found this helpful.

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