Threaded Vacuum Modulator Valve | 1965-1972 C4/C6 Mustang

Bill shows you how to install a Threaded Vacuum Modulator Valve on your 1965-1972 Mustang with a C4 or C6 Automatic Transmission.

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If your transmission isn't shifting correctly, then you may have a faulty modulator valve. Replace it with this Vacuum Modulator Valve from CJs for smooth shifts for miles to come!

Also known as the throttle valve, this valve controls vacuum to the transmission. As you press the gas pedal, it will apply higher control pressure for better quality shifts at higher RPM.

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[Passionate]

Excellent video very well explained. I have a 2008 BMW 750LI it jumps when i change the gear from park to reverse, Sometimes it will not go in to any gears at all . I had a lots of fluid changed it cost me more then thousand dollars on just the fluid changes . It still does not make any difference, The dealers do not service this car anymore. it is the vacuum line that is the problem but hard to locate there are to many lines coming from engine to transmission .
the car has 1056000 km on it, new transmission is not required . Thanks for posting the repair video.

[jensdavidsen]

Just changed mine this evening...1967 Ford Galaxie 500 convertible 390 2bbl with C6...there was no pin...but I had serious shifting problems before (shifted hard and at higher-than-normal RPM) but now it shifts very smoothly but at way low RPM...like 10MPH for 1->2 shift and around 20 to hit 3rd...

[robertclymer]

Thanks for posting! Great info and nice to know.

[yogibear]

The throttle valve is part of the kick down circuitry. The modulator and valve control mainline pressure per the engine load. ;)

[actorrobertcoffie]

I have a C6 transmission and I get up to about 55 miles an hour and it slips out of gear I have nothing and an engine just revs until I let it coast down to about 15 miles an hour and then it goes back into again. Could this be the problem

[marcosortolani]

Thanks for the video. Is the function of the Vacuum Modulator Valve only to control gear changes? When I adjust the Vacuum Modulator Valve the Modulator Pressure changes and often drops to zero bar.

[timothyfrost]

Excellent, simple and to the point, thank you. A question, could a bad Vac Modulator be the reason my '68 Torino can not excellerate of 30 MPH ? Thank you in advance.

[HunterUnbound]

Hello, I have a 1971 Mercury Monterey with a 5.8l 351W engine and an FMX transmission. The transmission control module went bad and so I bought a new one. I’m worried about the little rod that goes into the new module because it is very loose inside the module and moves around when I try to install it. I am afraid that the rod will fall out into the transmission itself. It is also a threaded module. Do you happen to have any advice for properly installing the rod and making sure it stays in place?

[TheTruth]

Where does the vaccum line go to the manifold? Is it a hard line or rubber? My mustang having shifting problems. Have to rev up high to get it to shift.

[MissouriJones]

Would this modulator prevent a C4 transmission from going into gear whether it be into Drive from Park or into Reverse from Park?

[howardwhitney]

The vacuum modulator "pin" is missing on my C4. Where can I buy one?

[howardwhitney]

Never got an answer on where to source a missing pin for the vacuum modulator on the C4??

[MustangGuy]

Mine won't shift in to 3rd at all may clean mine up see if it makes any difference then get a new one if so

[tryan]

Does the pin plug into the modulator or does it just kinda float freely in there?

[malliemartin]

Does a 94 Mustang have a modulatar valve?

[bucky]

Would this cause my ‘68 to stall when i put it in gear (C4) if it were bad?
She has been running great, and this just started last weekend.

[UnapologeticAmerican]

Would this cause the car to die when put in gear? My 67 will set and idle all day. But as soon as I put it in gear, it dies.

[nickpeacock]

Could the adjustment cause it to rev between 2nd-3rd?

[josetorres-marti]

valuable info.thanks.Looking where to buy one.Probably C.J.Auto.

[j.anthony]

Seems I have to remove that cross brace just to get to mine. Is that the only thing holding my trans in place? 😬