C-6 slipping in drive

[gotmudd]

i know that this belongs in transmission forum but i never seem to see anyone over there. my problem is that i have a 1969 C-6[ same truck as sig. and avitar]anyway up until i did body lift on truck a couple of weeks ago evrything was opperating just fine. when i lifted the cab i thought i disconnected the shift linkage,i was wrong[ if you have to step away from project MAKE SURE you double check what you have done up to that point] anyway my lack of attention to detail resulted in me hyper-extending my shift linkage up past the park pawl i got it to come back with a "little" force. now for the problem: when the tranny is cold it shifts like it is supposed to but after the truck is warmed up[ after 3-4 miles] it starts to slip in drive but will re-engage when shifted into 2nd. i checked the fluid it was a pint low so i topped it off with no difference. i thought at first it might be a band issue but then i thought, why would problem show up ONLY after lifting and hyper-extention of linkage? is there anything i should look for that could possibly be seen by dropping the pan/ my only other option is to drop tranny and have rebuilt, but before i spend three hours dropping it to the ground thought i would get input

 

[gotmudd]

meow

 

[snake]

Other than the filter being clogged up I would have a clue. When you say you drop it into 2nd and it re-engages, is it re-engaging into 2nd or 3rd? If 3rd, I'd say the linkage needs adjusting.

 

[gotmudd]

re-engages into second and when i shift back into drive it holds until i put a severe load on it then it slips but ONLY AFTER the tranny has warmed up

 

[gotmudd]

filter is fine, talked to tranny shop, they said that it sounds like i blew some seals because of to high of line pressure. when i had the timing problem i had to floor it for three miles to get it home and they said because the motor wasn't running right it might have caused too much line pressure taking out the seals. can get her built for @550bucks

 

[mhughes165]

that aint bad at all for a rebuild on a trans

 

[bottledgt]

i would unhook the linkage at the trans first and try this. put trans in D manually on the lever,then put the shifter in D and see if they line up correctly without having to move either of them.if its off, thats probably the prob

 

[gotmudd]

i would unhook the linkage at the trans first and try this. put trans in D manually on the lever,then put the shifter in D and see if they line up correctly without having to move either of them.if its off, thats probably the prob

not to be a smart ass[but since this is my thread, i guess i can be] i have already adjusted the linkage and if you would read what i started ,EVERYTHING WORKS AS LONG AS THE TRANNY IS COLD, that being said, tranny is TOAST

 

[Will]

I don't think anything is wrong with the tranny--except you screwed up the linkage.

I think if you could find a clutch and band application chart for the C6 you would find there is nothing unique to the DRIVE gear that isn't used for something else. If that's true, then some other failure should show up as well. I think when you were forcing the linkage through the stops you screwed it up and the spool valve isn't staying exactly in position. The heat mystery doesn't need to be a mystery. Who cares? It started after you did the deed on it. Maybe the valve gets slightly looser in it's bore because the large aluminum valve body grows more under heat than a tiny iron spool valve?

What I would do would be to drop the pan and pull out the valve body. Then put in a known good one if you have another tranny lying around.

Just don't let them parts changers rape you--don't take out your tranny. The C6 is the easiest tranny to work on. I did a soft rebuild and put in a shift kit in a day. I did not need to make a bunch of special tools for it like I did with an A4LD--just some retaining ring pliers and a little thought.
But you didn't smoke that tranny. You probably just screwed up the valve body. That's a snap. Just be clean when you are taking it in and out and use an inch-pound torque wrench to replace it. It's very sensitive to torque.

 

[gotmudd]

everything looks good internally, nothing bent or out of place, as for the valve body thing, i don't happen to have a 'spare' laying around. besides the fluid did smell a little 'funky' when i changed it and considering that the tranny is out of a '69 and i don't have a clue how many miles are on it, a rebuild ain't that bad an idea. besides i kinda want to beef it up anyway.i feel confident in tearing into a motor, but frankly automatics scare the hell outta me with all the hydralics and stuff,be my luck i change the valve body and that not be the problem anyway. what you say does make sense on paper though.