transmission problem


Old 07-10-02, 10:10 AM
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transmission problem

New guy here with a problem.
I Have a 1977 Ford F-250, 4x4, 400eng. C-6 trans.
several months ago the flex plate broke and the truck sat in my driveway for 3 months untill I made the time to fix it.
I have replaced the flex plate and got the truck going again, I had to back the transmission completly out to do this.
I believe I have put everything back right after alot of cussing and knuckle busting. But the transmission only down shifts once, and feels like it runs in a higher gear.
I'm not a mechanic but have gotten along to this point, just don't know much about transmissions.
Anybody out there that might have ideas for me? I would greatly appreciate it!,
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Old 07-10-02, 12:20 PM
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I believe you mean that it only up-shifts once (like from 1st to second gear).

And I believe you may have the concept of high and low gears backward. A higher gear will cause the engine to turn slower and the wheels faster. A lower gear will make the engine turn faster with the wheels turning slower.

So if all these assumptions are correct, then you are only able to get it to shift from first to second gear, right?

There is a link between the throttle on the carb to the transmission (I believe yours will be a bar with an adjustable part held together with a nut and bolt). It's a bar that tells the transmission how far you have the gas pedal pushed. If this is not adjusted properly (or wasn't hooked back up) you will get these kinds of weird shift problems.

You yanked the tranny and you aren't a mechanic? I'm no professional but I considered myself a mechanic when I did my first tune up.
Old 07-10-02, 01:34 PM
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Thanks Jason R,
Your right i do have it backwards. Told ya i wasnt a mechanic, Just an old farmboy. Been pretty lucky when it comes to taken things apart and putting them back together without any extra parts left over.
Pulling the trans out wasn't near as bad as the transfer case having to come out first, darn that was a heavy monster.
I was happy to get it all back together.
I was thinking about the kick down rod might be the problem just not sure of how to adjust it. the haynes book I used is not real detailed on that. were you talking about the kick-down rod (down shift adjustment)?
Old 07-10-02, 04:06 PM
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The kick down rod fell off of my old 302 maverick a while back and I never put it back on. It shifts fine through all three gears, when I jump on the gas pedal, it won't downshift to a lower gear.

I did the trans, on an old 67 stang several times and a comet all with a c4 trans. The c4 is similar.

Once I ran into a problem where it would not shift up. On my cars there was a vaccuum line coming from the back of the intake manifold, down to the transmission. It provided vaccuum to the trans, and that is how it knows how to shift. Since your car is around the same generation, I would assume you have a vaccuum line also.

It probably came off, or cracked/broken when you pulled the tranny back, and you might not have noticed it. Crawl under the car and look for a vaccuum nipple, and inspect all of your vaccuum lines coming from the intake manifold. I am willing to be that that is your problem.
Old 07-10-02, 04:11 PM
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Thanks JThompson,
I'll look it over first thing in the am.
Old 07-10-02, 06:26 PM
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Jeremy is referring to the tranny modulator, which does go bad and will cause a no upshift condition. If you find tranny fluid in the rubber line to the modulator, it's wiped.
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