Gear change up and down

[Nige]

73 mach 1 2 barrel 351c with c6 auto transmission

Car goes into 3rd before 30 mph and do not change down until about 10 mph is this normal.

Nige

 

[Hemikiller]

Factory spec shift points are in the Ford shop manual. If you don't have a copy, I can post the info later.

 

[Nige]

Factory spec shift points are in the Ford shop manual. If you don't have a copy, I can post the info later.

That will be great thanks

 

[Bill73Ragtop]

There is a small screw head in the transmission vacuum modulator that can be turned to adjust shift points. Pull off the hose and it's located inside the modulator hose housing.

Do a search on this forum since it has been addressed several times in the past.

 

[Pegleg]

Here you go Nige. Hope its legible enough for you

 

[Hemikiller]

Here you go Nige. Hope its legible enough for you

Pegleg beat me to it...

Being a '73, you probably have a dual area vacuum modulator, which are not adjustable. You could swap it for an adjustable one to tweak your shift points up or down a couple MPH, but if yours are way off spec, you probably have junk in the governor, or more serious problems.

 

[Nige]

Here you go Nige. Hope its legible enough for you

Thank Steve for the info Nige

 

[Nige]

Here you go Nige. Hope its legible enough for you

Pegleg beat me to it...

Being a '73, you probably have a dual area vacuum modulator, which are not adjustable. You could swap it for an adjustable one to tweak your shift points up or down a couple MPH, but if yours are way off spec, you probably have junk in the governor, or more serious problems.

Yes it has the dual modulator is it ok to swap for an adjustable modulator and what would be the best colour . Nige

 

[Hemikiller]

Looking at the charts, your trans seems to be operating within the ranges spec'd by Ford. You could replace the modulator with a single, but it appears yours might be adjustable. If it looks like the unit in the pic with the nipple along the axis of the modulator, then you can adjust it. You could also increase the length of the pin to increase shift mph and firmness.

https://www.ford-trucks.com/forums/971599-auto-trans-vacuum-modulator-color-coding.html

 

[mudbilly]

73 mach 1 2 barrel 351c with c6 auto transmission

Car goes into 3rd before 30 mph and do not change down until about 10 mph is this normal.

Nige

That sounds similar to how my c4 shifts, during NORMAL acceleration. Standing on it changes the shift points dramatically, although I do have a shift kit installed.