Got my truck to road-safe/worthy status, now trying to fix all the bugs to get it to reliable/not-worrying-that-something-will-turn-loose-at-any-moment status. I am a novice wrench turner, and new to working on older vehicles. I can find my way and fix things as long as I'm pointed in the right direction. Here's my dilemma:

1977 F150 / 2WD / 351M / 2BBL / Auto Trans

Whenever you let off the gas pedal, the transmission doesn't "coast". At all. It downshifts, kind of like my own small-scale jake brake. While I'm sure this is great for saving wear on my brakes, I can't imagine it's fantastic for the life of the transmission. I'm not sure if there's any correlation, but here's the janky homemade linkage extension under the hood:



I'm not sure if that has anything to do with this issue or not. The linkage is loose as hell, have to tighten that loose nut to keep my sanity every time I take it for a spin. I've been looking for a replacement, but due to my limited knowledge, I don't know the correct terminology for that linkage. I've looked for images of a "correct" set-up, but for the life of me, I cannot find it. I'm not sure if it's the wrong linkage (too short), or if someone shortened it and added that extra piece, or if it's the right pieces and I am totally barking up the wrong tree.

Any help is much appreciated.

 

http://www.flickr.com/photos/jerkmountain/10708317083/http://www.flickr.com/photos/jerkmountain/10708317083/]image[/url, on Flickr

 

My money is on it's that linkage, that is the kick down linkage. It tells the transmission when the throttle is wide open so it kicks down a gear. It needs to be all the way up/forward when the throttle is closed/idling. And be all the way down/back when at full throttle. In the pics it looks like it's pretty far down/back and I'm willing to bet the tranny thinks the throttle is wide open all the time and that is why it is doing that.

I'd start by just disconnecting it, you do not need it to drive. Then see how it drives and add it back in when you can do it right.

Also you need an Edelbrock part number 1483, it's the ford kickdown linkage lever adapter, it will allow for the linkage to be attached and adjusted properly http://www.edelbrock.com/automotive_.../1000/1483.pdf

Looks like you have an aftermarket manifold that is taller then the stock one. Cause of this the stock linkage rod will not be long enough to work properly. Sometimes it can be bent enough to work, sometimes you're better off just making another one out of some rod and heim joints or spending some bucks for a nice aftermarket linkage.

 

Gotta agree with BruteFord, your kickdown linkage is funky. This is the connection between the throttle and transmission that puts the tranny in "passing gear" when you floor it. If it isn't set up properly your transmission can shift between 2nd and 3rd whenever if feels like it.
Disconnect it for now. Your tranny will function normally.

 

X3. Disconnect the linkage to test. On the C6, unlike some other transmissions, the linkage's only function is to kick down the transmission into a lower gear when the throttle is floored.
I also agree that with an aftermarket manifold and carb, the stock linkage won't work without modification. It looks like thats what a PO has done poorly.

 

Here is the setup on my carb. Notice the additional piece bolted to the throttle arm. It adds a lever for the kickdown rod and adjustment screw. Like everyone has said, you need one. It also moves everything about 1" or more away from the carb so some tweaking is needed to line things up.

 

Thanks so much to everyone for the insight! I will tackle this issue soon, and report back with my results.