'78 F150 4x4 400

I've been leaking tranny fluid since I got it 4 months ago and have been adding 1/2 qt fluid every week or two and keeping an eye on it. It would drip a few spots when sitting but was always pan-wet after driving. I kept wiping it away and watching. It seems to be coming from the cover plate on the front of the bell housing.

So, anyway I figured front seal...I'll eventually have to rebuild and just want to keep it running for now. I put in 1/2 qt Lucas trans fix which seemed to stop the leak for now. However, the shifting is very very soft.

I've confirmed that I at least have 2nd & 3rd gear. I'm only getting one shift from a stop. I can manually shift the gear lever into 2 and get no shift that I can tell from a stop then shift to "D" and it shifts. Trying to manually shift into low (or 1) seems no diff than "2". In fact, I don't even feel that "click" detent on the shift column when trying to manually put it in low.

Before adding the Magic Lucas Tonic, I could feel 3 distinct shifts. First gear was fairly quick from a stop (at maybe 10 mph?) but it there. Now I don't feel anything at all.

Is it possible it's starting in 2nd? Or is the shift from 1st to 2nd just more mushy and unnoticeable with the Lucas Goo?

Thanks for any input!

 

It is possible that you are starting off in second gear. If you select second gear it wil be in second no matter what. It is a unique feature to the C6 iirc . Investigate your linkage to make sure it is working and adjusted properly. At some point Ford change the detent method. Early valve bodies had the detent on the manual valve in the transmission, later have a "rooster comb" internal linkage for more positive control. Either way your column detents have to coincide with the transmission lever it it will be in between gears.

 

It's a Ford standard. All Ford automatics start in and hold the number that's on the PRNDL. If you put the shifter in 2 it starts in 2 and stays in 3. On five speed autos that have a 3 position it will start in 3 and stay in 3.

 

OK...Thanks guys. So then I do in fact have 2nd and 3rd. I'll check the linkage and see why I am unable to manually shift into 1st.

As for driving in "D", what would cause the tranny NOT to downshift into 1st on stop OR NOT start out in 1st gear? Is there any chance the modulator or vacuum be involved?

The reason I ask is because this also coincides with my re-gasket of the intake manifold when I had the hoses disconnected and discovered the steel line to the tranny flopping around when I went to reconnect the rubber hose to the intake.

 

Is the kick down rod attached? If not, the lever on the trans might be moved to the kick down position, it needs to be kept in the other position if there's not rod attached.

The modulator won't affect the trans not dropping into first gear but does affect how the trans shifts. Pull the vacuum line off the modulator, if trans fluid is present, the modulator is bad.

 

You may not be selecting Low gear.
Your C6 transmission should stay in Low when selected, 2 will stay in 2nd, but when D range is selected you will have all 3 gears.
Check for worn or out of adjusted linkage.
Disconnect the linkage at the transmission and move the lever through the ranges.
You should have 6 positions.
PRND21

 

Now that's something I didn't check. I moved it around quite a bit from up top while trying to get the intake back on...had to pull it to one side and tie it up out of the way. I could have bent or damaged it.

 

I'm pretty sure I'm not. When I select P, R, N, D, or 2 I can feel a "click" and the shifter "sorta" (explained below) locks in that spot. When I try to select 1 it feels like I'm not able to pull far enough down to engage it.


When I manually shift the steeing column lever the transmission only engages the correct selection once the pointer/indicater goes past the desired selection by one. For example, for reverse it slides to N before engaging, for D it slides to 2.

Once the tranny engages, I push the lever back up and it locks in the correct position. Therefore, it seems like I can't engage "1" manually because I'm unable to move the shifter down far enough.

Now, that would only affect MANUALLY shifting into 1st gear. In D I should be able to feel all 3 gears in 2 shifts...1-2 and 2-3.

As soon as some of this snow melts I'll check out the linkage, kickdown rod, vacuum connection, and modulator as you guys have suggested.

Thanks a ton for all your input. If you guys think of anything else please chime in!!

 

KD linkage, modulator or vacuum don't come into play.

Look for either worn or out of adjustment linkage.

The bit about N being selected for R is a give away.

If the kd linkage was down too far the upshifts would be very high.
If the modulator or vacuum were wonky that would also cause high shift points.

Other than manual linkage the only other contributing factor is governor.

Linkage first.

 

I also have the same trouble - no first gear until I let the engine warm up and then it takes quite a bit of throttle to finally get her going. I replaced the fluid and filter and no leaks. I read in the Chilton manual about a band adjustment on the C6 but haven't tried it yet. Any ideas? It's a 1977 f150 (400M) with a C6

 

Band adjustment on a C6 only affects 2nd gear.

 

maybe torque converter - probably have to drop the tranny. I was hoping for something a little less involved

 

If it's a torque converter you will have problems in all gears, not just first gear. Old, worn forward clutch seals are a well known problem in these transmissions. That's probably your problem. The trans needs a rebuild to fix this.

 

I was afraid someone would say that. Is there a quick fix for a month or so I'll need to get some room in the garage to drop the tranny? I would imagine seals are not too expensive?

 

Seals are very inexpensive. If you are taking the trans out and tearing it down I would spring for a master rebuild kit. It's not too expensive, either, and it doesn't make sense to tear the trans down and only fix the seals in one clutch. If one set is worn out, the others are probably not far behind. And the frictions should be changed, too, and come in a master rebuild kit.