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-   -   C6 won't shift (https://www.460ford.com/forum/47-driveline/246643-c6-wont-shift.html)

Robert Peak 03-14-2019 04:13 PM

C6 won't shift
 
Hello to all new to this forum, have been to nearly ALL forums where C6 is discussed and still doon't have an answer to my problem, either no one responds or they give stupid answers!!
So here is the problem, when I have the engine running and I shift down into low, it will shift up to 2nd gear but thats it, to get in drive or back to PRN I have to shut the engine off. If I'm driving along and shift down to 2nd it will not go back to Drive. Now this will happen with the shifter hooked up or compeletly unhook from the trans. So I know its not a shifter problem and no the motor mounts are not broke. No transmission repair shops have been of any help either. Please help.

If this problem sound a bit far fetch, I know, but its for real. Thanks

Robert

gregaust 03-15-2019 04:09 AM

What is the history on the trans ? What is done to it ?

Is the modulator valve in right? Modulator connected to full vacuum? Modulator pin preload checked ? If the modulator you are sure is all in right and functioning it'd have to be a valvebody issue

Robert Peak 03-15-2019 07:15 AM

Quote:

Originally Posted by gregaust (Post 1661985)
What is the history on the trans ? What is done to it ?

Is the modulator valve in right? Modulator connected to full vacuum? Modulator pin preload checked ? If the modulator you are sure is all in right and functioning it'd have to be a valvebody issue

History; I bought the trans nearly 20 years ago, was still in the original car it came in. I installed it in my 63 F100 with a 390 FE.

Whats done to it; As far as I know it stock,
Its been to several shops since then and as far as I know the modulator is in correct, not sure on the pin preload check. If its something I can check with my limited knowledge I will.

Some more on the problem, a couple years back the wife bought me a B&M shifter, I installed this and shifted into low with it and started to shift back up when it wouldn't move, needless to say I put so much pressure on the shifter that it destroyed the cable. It shifts out perfect when taking off in Drive.

Last year I put it up on the rack and had a buddy sit in it while I tried to shift from underneath, I put a cheater bar on the trans shifter arm, when I saw the arm starting to bend I stopped.

I know very little about transmissions, but to me it feels like that what ever it is is very solid. .

EDIT; I have two valve bodies that I have used, does not seem to have any change to the problem.

Robert

thermod 03-15-2019 08:06 AM

Robert....cable snapped,cheater bar...go a little easier,my friend! Next thing will be a bigger hammer. So,when you shift to low or 2nd,are you saying when you put it in D it doesn't shift or it physically won't go to the D position?

Robert Peak 03-15-2019 08:20 AM

Quote:

Originally Posted by thermod (Post 1662003)
Robert....cable snapped,cheater bar...go a little easier,my friend! Next thing will be a bigger hammer. So,when you shift to low or 2nd,are you saying when you put it in D it doesn't shift or it physically won't go to the D position?

:laugh:Yeah, I sometimes get carried away, or should be... But yes, the trans will not shift into drive or any thing above drive.PRN. physically or otherwise.
Is there something inside the trans that would be moving into a position that would block the manual valve from moving when the engine is running? Like I said above its the same with two different valve bodies.

Robert

gregaust 03-16-2019 01:48 AM

Ah ok , I understand now .. You can move the manual lever ok stopped , but engine running it's stiff?

Is the valvebody detent in the valvebody itself , early type? Or later type with the detent roller and spring in the case?

You could check line pressure , that'd be the only thing that might make the manual valve stiff but in saying that a lot of valvebodies run up near 200 psi and no issues .

Robert Peak 03-16-2019 07:48 AM

Right, but stiff is not quite right, stuck would be closer. I have both valve body types and it does it with both. I don't know how much it would take to move the manual lever but like I said, not even with the help of the cheater bar could I get it to move. Thanks

thermod 03-16-2019 08:02 AM

Did you check out the park pawl,park rod or the park linkage? That's about the only thing I can think of at the moment.

Robert Peak 03-16-2019 08:12 AM

You know what, I just signed back on to edit my post above to ask about the rod. Was looking at the shop manual and was studying that area, that would seem to be the only thing that is connected to the shifter that would be a solid connection. If it wasn't for the fact that this trans has performed perfect when driving normal I would have replaced it, living with the shift problem has been annoying but nothing drastic. I will pull the tailhousing and see if anything looks out of place, or maybe has some markings that don't look right. Will get back with my findings. Thanks for the help..

gregaust 03-17-2019 02:03 AM

3 Attachment(s)
You can see most of the park linkage with the pan off . It might well be something there .. Could be the park linkage hitting the bracket that it is guided through

What I was getting at with the detents was that it didn't have both the detent spring in the case plus the detent in the valvebody fighting each other ..


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