Hey everyone,

I have a '75 F250, FE390 w/ a C6. There is transmission fluid slowly leaking from the linkage on the transmission where the shifter levers attach. Is there some kind of seal that might have failed? It's the area highlighted with light in the photo.

Also, there seems to be some sort of plug next to the linkage, I tried to tighten that in case it was loose and the source of the fluid, but didn't make a difference. What is that plug for?

 

Funny on the timing you post this! Yes there is a seal. You can replace it from the outside. You don't have to drop the pan. Mine is leaking also. It's getting replaced either tonight yet by my mechanic or tomorrow morning before the truck has to go to the window shop!

My truck is a '77 F150 4x4 with a C6 trans.

Later, Shortbox4x4

 

Thanks for the reply, I've been trying to find out how to do this without dropping the Pan. If you can pick his brain I'd love to hear how it's done.

 

If he's doing it tomorrow morning while I'm there I'll take a few pictures.

The seal is like $7-$10. From what I remember him telling me is basically you get a tool with a pick/hook and you pull it out. Then press/tap the new one in.

Later, Shortbox4x4

 

i second on the timing being funny. i just posted the same question.

 

First myself I would call that a leak or a even a drip!

Second I believe there's a o ring behind the shift lever not a seal but I may be wrong. From what I learned recently from having the wrong type shift lever on the project I was doing is that it doesn't just come off. From what I read the shift lever only comes out by dropping the pan and valve body to get to the nut on the inside. Without doing that I don't know how you can pry a seal out that is covered by the shift lever. The kickdown come off with the nut but that's it unless there's something I don't know.

 

From what I've seen....it's called a seal. Kinda like the rear seal for the yoke on the tranny.

If Dave and Bud (the mechanics) say they can do it etc....I believe them. They've never steered me wrong. They rebuilt my TH400 trans for my '68 Firebird 400 3 years ago and haven't had a single issue with it and there is a 550hp motor sitting in front of the trans!

I'll find out today though on the C6!

Later, Shortbox4x4

 

I just posted a how to on this on a facebook group. Gimmie a few minutes I'll post some pictures.

 

I'm curious on this one too. The one I had was from a column shift truck like yours and I needed the arm reclocked for a floor shift. I ended up using a B&M arm that clamps on the existing arm after a portion is cutoff. It would be nice if the arm was removable from the outside.



Ok. I just googled this since I didn't believe it. What your guy is talking about is the o ring that is for the kickdown lever attached to the shaft. The other seal which your looking for that is like a t case yoke type is behind the shift lever. Shift lever has to come out and that means pan and valve body.

 

Leaking shift lever seal Ford c6 101

I took these pictures while rebuilding a customer's c6. The trans is still mostly dissembled. I'll speak to you like it is tho as you'll be doing this under a vehicle.
Shift lever:


1/2 inch wrench removes the kickdown nut. Remove lever and it'll look like this:


This oring is critical, it seals the kickdown rod and is easily moved/bumped/displaced. After the kickdown is reinstalled, make 100% sure this o ring is still in place
Now you'll need to drain the transmission fluid.
Once drained, set pan to the side. Drop valve body by removing the 3/8 headed bolts ONLY. Set valve body in pan.
It should look like this below:



With the valve body out of the way, you should be able to remove the kickdown lever entirely. It pulls into the case.
Ok now there is a large nut on the inside of the case which is holding the shift lever in.
You'll need a large adjustable and a 7/8 inch wrench.
The adjustable holds the shift lever in place on the outside of the case while the 7/8 removes the nut.


Once loose, pull the whole works out.
I didn't get a shot of the old seal, but it's just a seal..... pry it out, hammer new seal in.


Reinstallation of the lever is a lil tricky on post 76 models. Early c6's used the valve body for shift detents. Later ones like the one I am picturing used a spring loaded roller for the shift detents. While trying to put the shift lever back in you'll need s screw driver to push the spring loaded roller down so you can get everything in place. No big deal, but this picture from inside the case will help you visualize it all.


Once everything is reinstalled, make sure you are in park still and didn't move anything.
You'll need to be careful because you can over extend the shift linkage and it'll bind.
You won't be able to see this from under the vehicle, but this is reverse:


and this is park:


Ok, so another common leak on the c6.
People often blame the convertor or pump seal for a small leak from within the bellhousing. 90% of the time it is the servo lever pin.

So what is the servo lever pin?
The servo engages the band on the 1-2 shift and releases on the 2-3 shift. It pushes the servo lever, the pin holds that lever in place.
Servo lever:


The lever is installed from the bellhousing area with a small 1/2 inch cup plug. When installing it needs silicone. Ford even had a tsb on it. (warning, in the next two pictures, the transmission is upside down, the servo lever pin in the bellhousing will be on the bottom, favoring the passenger side) This is where the cup plug is:




If you clean that area really well, and put some silicone in there, it should stop the leak. If you ever have everything apart, smear silicone on the cup plug before installing.

Ok so you've got the shift lever and seal in place. Now install the 7/8 nut, tighten it. Make sure you are still in park. Next install the kickdown rod. Make certain the oring stays in place. Reinstall the kickdown lever and 1/2inch nut.
Reinstall the valve body, taking care to get the kickdown and shift lever to seat in their proper place. This might take a little jiggling. Reinstall the 3/8 headed bolts, and don't overtighten them.
Install pan, refill with fluid.

Any questions?

Good luck
Drew

 

New seal and oring are $3.24
1973-1992 Ford Bronco Automatic Transmission Control Shaft Seal - Transmission - ATP 73-92 Bronco Automatic Transmission Control Shaft Seal - 14907-05535844 - PartsGeek

 

That's a great write up. I wish I had that a week ago it woulda eliminated a lot of searching and guessing.

This guy here has a pretty good video of basically what was just explained above. Around 4min and 8min are the best shots of it.

 

Well next time ask me :P

I've built many c6's and I take a lot of pictures.

 

GREAT write-up!! Wish they all (including my own) were as clear and concise!

 

I'm going to remember this since I may attempt a rebuild. I've done quite a few motors but never a trans. I was always content with the 4spds but been thinking about converting 2 more trucks I have to auto...but all takes time. The one I was referring to earlier was C6 I swapped in place of the 4spd in my father in laws 65 F100.