C4 Modulator

[ol gray mare]

What's the difference between the green striped and the yellow striped modulators?

 

[jckkys]

Viperwolf may know. I could never find any info on these. I only know my '77 C4 came with a yellow stripe. That said, I bet the green stripe would work as well.

 

[Slowleak]

Check out this thread:

https://classicbroncos.com/forums/archive/index.php/t-162961.html

 

[FordBronc]

For 73-79 Ford trucks anyway...Here is some trans modulator talk from a friend.

"Check the vacuum modulator and the line that goes to it.Check the line for kinks or other problems, make sure it hasn't come off. If the line checks out, take the line off where it connects to the modulator. If trans fluid leaks out, its bad. If no fluid, it still could be bad. They're simple to replace, disconnect the vacuum line, remove one bolt that holds the clamp in place and the modulator comes out. It has an o-ring seal.

Modulators are identified by the color of the stripe. Pretty much the "go to" one is the black stripe. If they don't show that one in the catalog, go with the green stripe. Avoid the pink stripe. That one is a dual diaphragm version that has two vacuum line going to it. If by chance you have one of these, replace it with one of the other two and use the vacuum line that goes to direct manifold vacuum, cap the other line.

When you pull the modulator out, be careful. There is a pin that goes in the modulator. Sometimes it comes out with the modulator, sometimes it stays in the tranny. If it comes out, don't lose it."

 

[jckkys]

I've tried both the yellow and green stripe modulators and found no difference in transmission operation. I just ended up using the yellow one that was OE. The above chart is informative but doesn't include Broncos. My '77 Ford truck shop manual doesn't discuss the modulators. So going with the OE part that has worked perfectly for 45 years seems to be the safe bet.

 

[ol gray mare]

I'm going with the yellow stripe on mine, its what came on it. Thanks for the replies.