Ok for an 85 6.9 with a c6, the most important question is. Does anybody have a clue as to why it won't shift into reverse? And why will it not properly shift gears? If you put it in drive it will not shift out off first unless I manually do so. It also will not shift back to first art a stop unless you romp on it. It does have enough fluid, and it will aid in to reverse after it sits a while. Please help!

 

The manual shifting in a C6 usually indicates a bad modulator or the lines going to it.

The other issues you're describing... you might be due for a rebuild, but maybe a transmission guru will chip in here.

 

Yeah if was fine until I replaced the front seal and now its acting up and it has less that 50000 miles on it. Is the modulator your talking about on the injection pump our the tranny

 

It's on the tranny, passenger side towards the rear. It's a small vacuum pod with a single vacuum line going to it. Make sure it's hooked up and has vacuum. Rock Auto shows them for under $10.

IIRC, the C6 has 2 bands, one is for 1st and reverse the other for 2ond and reverse. I think they are both adjustable externally, but I could be mistaken and confusing it with the C4. Even if they are not both adjustable externally, the 1st and reverse one is. I don't recall the procedure off the top of my head, but you should be able to find out pretty easily with a search. There's a repair manual for the C6 in the parts stores that's pretty decent.

 

Did you get your torque converter seated properly? Fords have 2 "tabs" you have to engage.

 

Here's a recent discussion on the modulator:

https://www.ford-trucks.com/forums/1...ift-issue.html

 

Yeah nownow what's the thing on the drivers side of the trends where the shift , linkage and kick down linkage connect to? I took the linkage off that thing you think that might of screwed it up when I took that nut off? Where are the bands at?

 

Yeah nownow what's the thing on the drivers side of the trends where the shift , linkage and kick down linkage connect to? I took the linkage off that thing you think that might of screwed it up when I took that nut off? Where are the bands at?

 

I was told that dexon III / mercon brands transmission fluid would be good could that possibly be the wrong fluid and if it is would the trans be done for or do you think if I put the correct type in that it could fix the issue?

 

Could you please give me more of an explination an that please?

 

Ok after the truck Sat all night it went into reverse just fine even took out to lock in the hubs once I started treating up my yard so why in the world is it only working cold and not hot?

 

Ok update, after a fluid change (did drain out torque converter) and changed the filter, it now goes in reverse after a trip around the block. After checking my Haynes manual I verified that I am using the correct type of fluid. Got it up to the correct level let it sit a while. I drove liked a half mile in reverse around and around my large yard and foot three tranny warned up, drive it a couple miles, got home and it went right into reverse.

 

Now it still won't shift out of first gear in drive. Will shift between second and third just fine, even putt a new modulator on it. Any suggestions on that. And yes I do have vacuum at the modulator. Going to do an in-depth check out the line a little later but everything is on good.

 

You have to spin the converter onto the input shaft, should fall twice. When my C6 wouldnt go into first or reverse it was the rear sprag. I have no idea what any of that means, thats just what i was told.

 

Idk out never had s problem going in first it was just reverse. I never actually drained out the torque converter if there was a different kind of fluid in it before I just drained out what was in the pan and put new fluid in and mixing it with what was in the torque converter and as sensitive as they are I guess it makes sense that missed fluid could of bed the issue with reverse. Idk reverse works now and that's the important part.