Replaced '71 C6 valve body - no park now FIXED

[Wixomhead]

Getting desperate , have searched extensively but can't find how to resolve.

While replacing shift shaft seal and o-ring - with the transmission in the car, on jack stands, on my back - the parking rod, which I did not know to pay attention to, fell out of place. (7D411 below)

I'm now on my second attempt to re-install it properly (ie removed the pan and valve body twice ). I can see/feel the spring loaded lever and after I re installed I can manually select park from the selector lever on the trans and it sure feels/sounds correct - I can hear/feel things click into place/smooth operation, nothing loose...but...the driveshaft will not lock, it still turns freely. There seems to be much more going in back there that I CAN'T see.

Any advice? Am I doomed to have to remove the tail section??

[1Bad55Chevy]

Is the valve body still off or did you re assemble everything?

Remember the park function is the only mechanical function on an automatic transmission meaning you can fully test it before putting anything back together. The clicking you are hearing/feeling/seeing is the spring detent inside. With the valve body off you can install the park rod and move it through its range of motion ensuring the park function works before putting it back together.

My guess is the engagement rod isn't set properly with the park engagement lever. You do not need to remove the tailshaft to fix this. I can't remember exactly if you can even access that piece from the rear of the transmission.

[Lee]

I don’t know if this might not be helpful in visualizing what’s going on.

[Wixomhead]

Thanks for the very quick replies guys. Yes, the "bubble" on the end of the actuator rod is def engaging/pushing aside the spring loaded lever (7A441). But that's as far as it goes before hitting something that won't move (the case?). The rod must not be pointed in the right direction.

@Lee's procedures call for the actuator rod to be disconnected from it's internal lever (remove the C ring). I did not do this - I've been struggling to install the rod and shaft together - perhaps disassembling afford an extra 1/4" of play required?

We will see - thanks again

[Wixomhead]

The rod is traveling the correct distance into the hole/guide.

The bubble, or whatever it's called, is definitely engaging the spring loaded lever (the pawl) at the bubble's widest point. (See pic #2).

But it's not - apparently - moving the pawl over far enough to engage the parking gear. Once I lean on the rod, pushing it another 1/4" inboard - towards the center of the trans - the pawl then moves far enough over to engage the parking gear and lock the driveshaft.

What to do next?

[1Bad55Chevy]

When you shove it in there by hand can you still turn the driveshaft? Or is this only not working when the linkage is hooked up?

[1Bad55Chevy]

I don’t know if this might not be helpful in visualizing what’s going on.

Good pics Lee...


BTW we might have a front runner here with the oldest active member... this guy joined JAN 2001!

[1Bad55Chevy]

Getting desperate , have searched extensively but can't find how to resolve.

While replacing shift shaft seal and o-ring - with the transmission in the car, on jack stands, on my back - the parking rod, which I did not know to pay attention to, fell out of place. (7D411 below)

I'm now on my second attempt to re-install it properly (ie removed the pan and valve body twice ). I can see/feel the spring loaded lever and after I re installed I can manually select park from the selector lever on the trans and it sure feels/sounds correct - I can hear/feel things click into place/smooth operation, nothing loose...but...the driveshaft will not lock, it still turns freely. There seems to be much more going in back there that I CAN'T see.

Any advice? Am I doomed to have to remove the tail section??

Is that your Mark iii with a blower on it?! I need pictures of this!

[1Bad55Chevy]

Getting desperate , have searched extensively but can't find how to resolve.

While replacing shift shaft seal and o-ring - with the transmission in the car, on jack stands, on my back - the parking rod, which I did not know to pay attention to, fell out of place. (7D411 below)

I'm now on my second attempt to re-install it properly (ie removed the pan and valve body twice ). I can see/feel the spring loaded lever and after I re installed I can manually select park from the selector lever on the trans and it sure feels/sounds correct - I can hear/feel things click into place/smooth operation, nothing loose...but...the driveshaft will not lock, it still turns freely. There seems to be much more going in back there that I CAN'T see.

Any advice? Am I doomed to have to remove the tail section??

I am really wondering if part 7A115 is was installed backwards... not flipped upside down but rotated 180 degrees on the Y axis... if that makes any sense

[Wixomhead]

@Lee - the linkage is not hooked up/part of the equation. When I insert the rod by hand it goes the seemingly correct distance BACKWARDS to engage the pawl at the "bubble's" widest point ... but not the seemingly correct distance SIDEWAYS to push the pawl far enough over to engage the parking gear (to halt the driveshaft). So yeah, when I push the rod IN and then (easily) a 1/4" OVER with my finger the pawl engages the gear and the driveshaft locks tight.

While writing this up and going back and forth with your (2) scans above - I JUST found the problem.......Next to the pawl in the above exploded view is p/n 7D414 - a spring loaded lever (park plate) that I don't see in the hole/haven't searched for - (again, on my back, car on stands, very little room to maneuver). It's plain as day in the picture below that park plate must rest against the tip of the rod - forcing it up against the pawl - to close that last 1/4" loose gap. This is good news.

The bad news is the procedure / diagram demands tail housing removal. I am loathe to do this but now understand how the sausage is made / what is missing - thanks again for the scans!!!!

@1Bad - see pics below. I have two Mark IIIs, one Betty (parking pawl problem) and one Veronica (8-71 BDS blower). Besides this forum I am also LCOC 1984. Thanks again guys for the help. We're very far off topic now ... but this last parking pawl nightmare is the final, sideways, last step in Betty's Holley Sniper2 / in-tank electric pump install adventure (which went great BTW).

= = =

[Lee]

Betty and Veronica!

Man, if there was a contest for best car names, you are the winner!

[LithiumCobalt]

That looks like it will get up and boogie

[Wixomhead]

FIXED. The park plate spring, for whatever reason, slipped off (in front of) the park plate 7D414. The plate was then free to pivot backwards and stay there; hidden inside the actuator rod/parking pawl access hole. Some digging around with a set of thin dental instruments enabled me to a) pull/pivot the park plate into position and b) force the spring around and behind the plate - thereby forcing the plate forward into position next to the parking pawl. The actuator rod then pierced between the two, and the spring plate now presses the rod hard against the pawl - locking the driveshaft.

What a nightmare. Hope this helps others as it appears a leaking shift shaft seal and/or o-ring are a fairly common occurrence on these old C6s.

Thanks again for the diagrams - that made all the difference

[1Bad55Chevy]

I promise you that was a minor nightmare compared to pulling out the cross member in order to get the tail shaft off!