1971 Ford F100 shifting problems

Check your vaccum modulator but I would also check the kick-down arm linkage. Sounds like it is stuck in the full-throttle position which would cause it to shift late and hard.

Razor

Is it ate and hard on both shifts or just one. If on both, I would suspect the kickdown linkage. If the 1-2 shift only, I would look for a vacuum problem to the modulator or a bad modulator.

Lugnut

Pull the vacuum line off of the modulator. If it is full of transmission fluid you probably found your problem. You might have to replace the vacuum hose as well. The fluid will make it really soft so it will collapse on itself even after you put a new modulator on.

Tim

p> I have a 1971 Ford F100 with a 1975 302 V8 & c-4 auto trans.Recently it started shifting like I have it to the floor all the time.It winds out & shifts hard even when I barely step on the gas.Give me some ideas what the problem might be.Could it be the vacuum modulator?