Hello all and a nice holliday today.
My 66 Linc coupé with the C6 Transmission has a new problem. Everything runs fine and great, but when i want to speed up over 55-60 miles/h it shifts back and up in a higher gear and back and so on. The same with Kick down, only better to feel. it comes from one second to the other and it is even the tranny is hot or cold. Fluidlevle is exact.

hope, anyone has an idea
have a nice Party
Tom

Sounds like you have a vacuum leak to the vacuum modulator. The line runs from the left side of the intake manifold to the right rear of the transmission . I think you will find a ruptured hose or one that fell off. While you are at it make sure there is no transmission fluid in the hose or line. The modulator has a diaphram ,and if it fails it will allow transmission fluid into the manifold and be burned by the engine. If you do find leakage the modulator is an external part and is easily replaced.

Thank you for your fast replay! I will check it. Tomorrow.
greetz
Tom

Like he said. Had the same problem with my rubber hose that for some reason had accumulated oil. The rubber hose got flabby and had widened like a hot spaghetti causing it to fall off the modulator nipple. Make sure to eventually replace the hose connection.

We checked the Modulator and the Vac-line. Its ok.
Somone tells me someting about the gouvenor, some Ideas
Greetz
Tom

hi every body,
after fixing the Fulepump the C6 shifts perfect again.