C6 transmission park function

[1976kjell]

Hi

This is a forum for FE engines, but I hope its ok to ask a question about C6 trans

Its a relatively simple question; in park, the trans "jumps" out of park-postion. A shop was going to adjust it externally, but concluded that its something inside the trans that has to be replaced or adjusted. Is it a way to adjust or check the function of the park pawl without disassemblying the extension tail of the transmission?

[Drew Pojedinec]

I can't help on why it's jumping out, my guess is the spring isn't pushing the pawl that well.  Anyway I included a photo from one of my transmission builds so maybe you can get a visual on it.

[Drew Pojedinec]

Sorry I couldn't find a larger photo.

[1976kjell]

Thanks for the picture. I assume the extension tail anyway has to be removed

[Drew Pojedinec]

yes, but that is all.....
if you jack the rear of the vehicle high enough very little to no fluid falls out.

[jmlay]

The internal rod could also be bent.

[cammerfe]

What sort of shifter are you using? When I was in QC at T&C Livonia, we had a spate of trouble on C6 transmissions with the park function. It was due to the shifter not pushing the park rod far enough to completely get the pawl into position, or not holding it there. If the rod backs off, so will the pawl.

Another possibility is that the park mechanism has been 'chewed' by putting the trans in park when the car isn't completely stopped, and causing it to 'ratchet' down to zero. After a few times, the detents aren't all they should be.

Just a few possibilities.

KS

[1976kjell]

Thanks for helpfull hints so far. The original black ball shifter that originally controlled the cruise-o-matic-trans is still used. The lever on the attached image is installed, so it should be enough travel and possibility to adjust to get it work. In spite that the shop ment it was something inside the trans that didnt work, the external mechanism will be checked before eventually removing the tail housing and eventually the pan

[Gregwill16]

Agree with Cammerfe, start with the linkage/shifter first. I had one on my 69 Mustang that was not allowing full travel and it would not hold.

[C6AE]

Could be a defect, it is an old known problem, with an "almost" recall. Back,in 1968 my mother lost a car down the hill and into a pond because of this!

https://www.autosafety.org/ford-transmissions-failure-hold-park/

[e philpott]

Pull the pan first and check linkage, correct whatever you see and verify operation, pull tail shaft if needed

[stubbie]

Check your detent plate. The corners of the detent plate become round after years of operation.

[1976kjell]

I understand that the detentplate "holds" the stick in posistions, but where is the detentplate located in a 63 Galaxie with floor shift? Tried to google, but didnt found an answer

[cammerfe]

In the shifter mechanism.

KS

[e philpott]

It's inside the Pan

[Falcon67]

First step it to take the shift linkage off and place the trans in Park firmly by hand.  If you can pop it out of park in that condition, then the problem is internal.  If it's a shifter problem, you'll want to fix that quickly because if it's not putting the trans in park properly it could also not be placing the internal valve in the right place - which could hurt the trans.  The primary locator for any specific trans gear is the internal "rooster comb" and detent spring lever that positions the shift valve.  Anything external has to conform to the internal positions.  On my race trans/shifters, I place the trans and shifter in neutral, then adjust the cable, linkage,etc to fit the pin easily in the trans lever.  The go to first (or low in a stocker's case) and remove the linkage - the pin should slide in and out of trans level without binding and the trans should be firmly in that gear position.  Put the pin back in, shift to park, perform same linkage test.  If it lines up in the middle (neutral) but is off on the ends that has to be analyzed and fixed where possible. 

[cammerfe]

I suppose the correct answer to the location of the 'detent' is that there are actually two detent mechanisms involved. Since the problem, as was being addressed in the thread, above, was the location of the detent PLATE, the most likely answer is that it's part of the shifter.

However, as was said just above, there is also a 'rooster-comb' detent apparatus that's part of the transmission itself. As noted just above, it's inside the case and moved by the outside-to-inside mechanism. It not only the part that moves the valves in the valve-body, it also has attached the forward end of the park rod.

Both detents must work in unison to achieve the intended result. The external arm in the picture above has such a wide variety of holes to make it possible for everything to line up.

There, I hope we've completely covered the ground now!

KS

[1976kjell]

Yes, the external and internal detent mechanisms have to be synced. My 67 C6 does not have any rooster comb style detent plate (lower picture) either inside or outside the pan, but the manual shifter in the valve body has grooves that works with a spring and ball, shown in the upper attached picture. I guess the grooves/spring/ball have the function to detent the trans inside, instead of a "rooster comb"

[1976kjell]

On my race trans/shifters, I place the trans and shifter in neutral, then adjust the cable, linkage,etc to fit the pin easily in the trans lever.  The go to first (or low in a stocker's case) and remove the linkage - the pin should slide in and out of trans level without binding and the trans should be firmly in that gear position.  Put the pin back in, shift to park, perform same linkage test.  If it lines up in the middle (neutral) but is off on the ends that has to be analyzed and fixed where possible.

Thanks for a nice explanation, but what pin are wou writing about? Do you have a picture of a pin like that?