Leaking 727B transmission

[1963JAM]

What am I looking at, and how do I stop it from weaping? Pics are looking at rear of transmission. Also installed cork gasket, checked pan for straight clean gasket surface, torqued fasteners according to service manual and still have leak at gasket. Any other suggestions?

 

[69 Sleeper Bee]

That’s the new gasket ?
Looks like your 0 ring is leaking

 

[Lefty71]

Looks like a peanut butter and jelly sandwich. I know you said torqued to proper spec, but it really looks like that cork gasket is ripping right out of there in the pic you sent. Maybe El-Cheapo cork??? The Moroso Blue reusable gasket has been awesome for me......you know us racers feel defeated if we leak one drop of anything out of our vehicles..... 69SleeperBee is right, if the O-ring from the rear band strut is leaking down, or any other source from above, then the pan will take the blame before dripping off. Maybe blast clean with some brake cleaner and give it a look while running to see what shows up??

**EDIT** Since the trans case is aluminum, I normally use some Blue Loc-Tite on the bolts, and like others have said, barely torque them to the required amount...once you have a base built up on the threads with the Blue, you can always go back and give them a little more snug if the need arises.

 

[Doorkicker]

Jebus.... Welcome to my nightmare. I ended up buying a new oil pan and a multi-layered rigid gasket. And I also did about a half to 3/4 of what the manual said for torque. Hasn't dripped a drop since. But I think you'll find pretty quickly everybody has their own fix to a 727 leak.

 

[zyzzyx]

Yeah, looks like the O-Ring on that shaft is leaking. Can be replaced easily when you take the pan off.
Honestly, the best thing to do is to buy a cast aluminum pan and replace the gasket with The Moroso
re-useable gasket as mentioned earlier. The sheet metal pan is just like stamped valve covers. They
always leak!

 

[dvw]

The Band shaft can be sealed from the outside. Clean the area with brake clean. Blow it dry. Apply a small amount of RTV over the band pin. Cork gaskets work fine. Pan must be straight, no sealer, do not over tighten. By your picture, yours is definately over tightened. Use a nut driver. No need for a ratchet. Then go around a few times. It will settle. Watch the gasket. When it just starts to buldge it's plenty tight.
Doug

 

[1963JAM]

Excellent insight. I’ll be dropping the pan to replace my cheese melt sandwich gasket. Is the O ring a part bought individually or from a trans kit? I like the idea of the reusable pan gasket, I would think it would need longer pan bolts?

 

[1963JAM]

The Band shaft can be sealed from the outside. Clean the area with brake clean. Blow it dry. Apply a small amount of RTV over the band pin. Cork gaskets work fine. Pan must be straight, no sealer, do not over tighten. By your picture, yours is definately over tightened. Use a nut driver. No need for a ratchet. Then go around a few times. It will settle. Watch the gasket. When it just starts to buldge it's plenty tight.
Doug

The RTV idea sounds interesting. Is that a quick fix in a pinch? Does it hold up well exposed outside the case?

 

[1963JAM]

That’s the new gasket ?
Looks like your 0 ring is leaking

It was new a year ago. I now see the repair manual torque is too much. Pinched so much that cork corners are breaking away. But the undercarriage is well oiled. Don’t need the undercoating.

 

[Rick62]

If a 727 isn't leaking, it's out of oil.

 

[zyzzyx]

The O-Ring can be purchased at an auto parts store or hardware store. Just make sure it's Nitrile.

 

[Dave6T4]

I like the factory "o" ringed pan gasket used in the A518 truck transmission. They are reusable, but require longer pan bolts to do the job right.

 

[dvw]

The RTV idea sounds interesting. Is that a quick fix in a pinch? Does it hold up well exposed outside the case?

If it's clean it's a permanent repair. I like Ultra Grey RTV. I add it to the pin on every torqueflite I build. A 727 doesn't have to leak. I've built 30 or more in the last few years. No leaks.
Doug

 

[1963JAM]

I like the factory "o" ringed pan gasket used in the A518 truck transmission. They are reusable, but require longer pan bolts to do the job right.

What is the torque on the o ringed pan gasket so Hercules doesn’t crush another gasket?

 

[dadsbee]

Stick a piece of aquarium hose down the dip stick tube and syphon the transmission fluid out. Lift the *** end of the car to be certain there's no fluid that can weep around the pivot pin. Clean everything, scrub, clean, scrub, clean, scrub clean and seal up the rear servo band pin and I bet your "leaking pan" goes away. I used PRC for aviation fuel tanks. Hasn't leaked a drop...

Are you also certain that your shifter and throttle shaft seals aren't leaking.....

I have 3 automatics in the shop. None of them mark their territory anymore!!

 

[1963JAM]

Stick a piece of aquarium hose down the dip stick tube and syphon the transmission fluid out. Lift the *** end of the car to be certain there's no fluid that can weep around the pivot pin. Clean everything, scrub, clean, scrub, clean, scrub clean and seal up the rear servo band pin and I bet your "leaking pan" goes away. I used PRC for aviation fuel tanks. Hasn't leaked a drop...

Are you also certain that your shifter and throttle shaft seals aren't leaking.....

I have 3 automatics in the shop. None of them mark their territory anymore!!
View attachment 1405072

I’m dropping the pan to replace the crushed cork gasket. I that PRC permanent? What did you use for the pan gasket?

 

[dadsbee]

I’m dropping the pan to replace the crushed cork gasket. I that PRC permanent? What did you use for the pan gasket?

Plain old cork vs fancy smansy. No sealer against the case side and a little line of aviation gasket sealer around the outer edge pan side.

The PRC on the rear pivot pin is on there good, but can be mechanically removed. You don't want to pay for it though at $200 a pint. I just happen to have stock of it. As DVW noted Ultra Gray RTV will work just fine, just make sure you let it cure before refilling.

 

[1963JAM]

The O-Ring can be purchased at an auto parts store or hardware store. Just make sure it's Nitrile.

Where's the O ring? Does the shaft have to come out of the case? Looking through 66 service manual and don't see what I'm looking for.

 

[dadsbee]

The o ring is ON the pivot pin. You have to remove it to change it.. or them. Some have two.

 

[1963JAM]

The o ring is ON the pivot pin. You have to remove it to change it.. or them. Some have two.

To remove the pivot pin, looks like the tail shaft housing has to come off?