'66 C-Body Kickdown/Throttle Linkage Pops off/Disconnects at Upper Bell Crank When Start Accelerate/Shift Down

[fury fan]

Does the linkage popoff coincide with the trans shifting, or motion of the KD linkage?
Does this trans have PTK (part-throttle kickdown)? Is the trans (or valve body) a 71-newer? (do you need FT to get a 3-2 downshift?)
Can it pop off when doing upshifts, or when downshifts, or both?
Either by manual shifting or automatic?
Can you get it to pop by moving the accelerator while in Park? In Drive with foot on the brakes?

If we can separate trans shifting from linkage motion maybe there's a clue there.

I doubt the fluid is a factor, unless it has a heavier viscosity when cold, enough to make the throttle valve more resistant to movement when cold. But that's truly a corner-of-the-box issue.

 

[C-440-300]

Hi, fury fan, The popoff (PO) is part throttle and is not during shift, but just under load, like off the stop sign, or super accelerating to pass.
The tranny has a Transgo shift kit when I bought it 19 years ago. This issue just started happening about 6 months?
I could not honestly tell if the valve body is newer or not. I would think so. Later, I could find time to drop it all and check for #s?
It never pops on downshifting. If I leave it in first or second, it never pops. Shifting up or down never POs.
While in park, I get no resistance and it revs up to limit.
The only thing my sorry memory can recollect is perhaps a top off qt of fluid? But, I did as I mentioned dropped pan/new filter and put in AMSOIL this summer.
You think I could have something sticking or blocked passage?
It's only when cold.
Thanks!
Cheers!

 

[Sixpactogo]

You still dealing with this?? I'm pretty sure your problem is in the snap on coupler that fits over the ball shown in my post #7. PM me your mailing address and I will send you one.

 

[C-440-300]

Check the roundness of the ball-stud. Otherwise known as "wear". Nothing in the transmission should cause more stress up there than just the linkage moving itself.

Also check the rod end for a firm engagement with the ball-stud, too. Maybe some good wheel bearing grease might heop it move easier?

CBODY67

Yeah, either the ball is loose or worn, the socket is worn, or the spring clip that keeps it together is bent or worn. If all of the parts are moving freely in the same plane, that’s really all it can be. If there is an issue, you can build a new link with spherical rod ends from the hardware store and it’ll last another 50 years.
Travis..

I just adjusted my kick-down linkage on my 65 Sport Fury a couple weeks ago. The service manual tells you exactly how to do it. If yours is set up properly and the rod falls off of the ball, you probably need a different rod. I have a couple of them. I believe they were the same for 383 and 440.
Maybe all you need is the threaded connector shown in this pic.

View attachment 667003

View attachment 667004

Good that you originally had a 440, as I believe the intermediate/vertical rod is shorter for the 383, and too short to adjust up to the 440 length. (but that is based on tinkering on a small sample size)

For my anecdotal experience, see here:
No avoiding it; I MUST get NEW Linkage Hardware Now Right? Kickdown Not Kicking.

Yes, the vertical rod is longer for 440 vs 383. You can screw the 383 rod all the way to the limit and it will just barely work on a 440.

Don't drive the car until this is properly operating or clutch damage will occur!
Mike

Gents! I owed you pictures and I finally got them. You may believe it, even if it seemed unlikely. I taped my fon and a flashlight under the hood and focused on the connector/rod and went around the block a few times, taking it easy and flooring it. It ends up that my motor mounts are soft or just not doing the job. The engine tweaks so far that the rod interferes against the firewall and or the accel cable. I caught it on video and here are some snippets. My solution that has worked so far is a torque strap. The webbing kind, come-along that Oldsmobile '80s Grand National used was my first try, because it was easy. The webbing gives too much when I hit it hard, but it lasted through regular freeway passing/shiftdown. I ended up using a chain with an S hook on the upper mounting bracket hardware (between the ears so as to even the load - not trying to break them off as I have heard happen) then connected, below, to the steering box bottom bolt. The S fits nicely right on to the bracket. No give and no noticeable deformation of the mounting upper bracket. If memory serves me, this all started to happen after I started punching it with some buddies. It just kept getting worse.
I forgot to mention that I installed two new 440Source designed motor mounts after I proved it worked. The mounts that were in there about 15 years were just regular items from O'Reilly's.
Thank you so much for paying attention to my plight!
Cheers and Happy Belated New Year!

(The pic may look like the rod ball is broken/missing some metal. It's not. The video is just from a cheap Android thingy. The clip is very tight/strong, too.)

Normal running:

Punching it HARD and it starts to pop off:

Returning after popped:

Cruising: (The rod ball is perfectly fine. The video is low quality.)