Hello gents

I have a custom 1978 f150 stepside . The previous owner put a 460 7.5 liter engine in it from a 1977 lincoln connected to a 3 speed auto transmission.

The truck had some revving issues which mentioned it would not rev above 3000 rpm. But that's fixed now.
However then the transmission stopped shifting into third.

Any ideas why that might be?

I changed the oil and it was not Burnet but was not fresh, a so cleaned the filter.

Still didn't shift into 3rd.

Aprreciate your input

Sam

 

That's going to be a C6 transmission. Check the vacuum modulator and the line that goes to it.
Check the line to make sure it hasn't become disconnected and check the condition. Look for kinks or breaks in the steel line and check that the rubber hoses on the ends are in good shape.
If the line checks out, pull the hose off of the modulator, if fluid leaks out, its bad. If no fluid drips out, it could still be bad.
Changing it is easy. One bolt and one hose. The modulator pulls out, careful, there's a pin in the end of the modulator. Sometimes it comes out, sometimes it doesn't. If it does come out, don't lose it, you'll need to install it in the new modulator.

 

thank a lot for that.

I will go through it this weekend i hope.

 

x2 on the modulator.... May also want to check/adjust the intermediate band. My C6 went from 1st to 3rd, band was really loose. After band adjustment, New modulator, and vacuum line, shifts like new.


Jeff

 

thanks Jeff

forgive my ignorance but what is /are intermediate band?

thanks

 

A quick search will get you more info than I can type. There is a bolt and lock nut just above the linkage on the side of the trans. You need to loosen the lock nut and tighten the bolt to ( can't remember the torque setting) then back it out 1 1/2 turns(??) then tighten the lock nut. This band is second gear.

Jeff

 

Like Jeff said, the band adjustment is just above the manual linkage on the driver's side of the transmission, see the picture below.
To adjust it, first, Ford recommends replacing the lock nut with a new one because this is a sealing nut but you can usually get away with reusing the same nut.
Clean the threads of the stud sticking out. Hold the adjustment stud with a wrench and loosen the lock nut, then tighten the stud to 10 ft/lbs. Then back off the screw exactly 1 1/2 turns. Hold the stud to keep it from turning and tighten the lock nut.

 

Thanks Mikeo0

gonna take a stab at that now

 

hello gents,

it was the Band adjustment. after a few tries and test drives, it shifts like the good old days now.

Thank you all

 

Glad it was one of the "cheaper" fixes.

 

That's the best kind of fix, 100% satisfaction and 0% dollars invested. Good job!!

Jeff