Transmission Gaskets for C-6

[ponypastor]

My C-6 transmission, mated to a 429 SCJ, was completely rebuilt and its pan was sealed with a rubber based gasket. But it leaks, despite attempts to tighten the bolts. Anyone else experience the same type of leaking with rubber based? 

And where can I locate a cork-based gasket? My local auto parts stores only carry the rubber based units. Thanks.

 

[Canted 393]

These are some of the best 1s I have ever used, they also make some for the 9 inch 3rd member that work great. pan gasket https://www.summitracing.com/parts/lub-llt-f0c6

9 inch gasket https://www.summitracing.com/search/product-line/lubelocker-differential-cover-gaskets/part-type/differential-cover-gaskets/differential-case-design-type/ford-9-in?SortBy=Default&SortOrder=Ascending

 

[secluff]

Hello, ponypastor,

I have had the same problem when  I tried one of the rubber style gaskets. No matter how snug the bolts were tightened I still had some fluid seepage. Our shop transmission Master tech refused to use them. He has repaired some transmissions where he had found stopped up filters and pieces of silicone sealant caught up in the valve body. This was a result of grease monkey and back yard shade tree mechanics using gobs of sealant trying to seal the rubber style gasket from leaking.

Use the cork Ford gasket C6AZ-7A191-B. Some parts houses may be able to cross that number to their version cork gasket. You could also try your local Ford or Lincoln dealer as some of them still have stock on that gasket even though Ford has discontinued it. It can also be found online at sources such as E-Bay by using the Ford part number. 

 

[73pony]

These are some of the best 1s I have ever used, they also make some for the 9 inch 3rd member that work great. pan gasket https://www.summitracing.com/parts/lub-llt-f0c6

9 inch gasket https://www.summitracing.com/search/product-line/lubelocker-differential-cover-gaskets/part-type/differential-cover-gaskets/differential-case-design-type/ford-9-in?SortBy=Default&SortOrder=Ascending

+1 on the lubelocker. Never had an issue.

 

[Kilgon]

A couple of things to do that will also help is to peen all the bolt holes and then to torque the bolts to 12 to 14 ft lbs.  Also tighten in a similar order as shown below alternating from side to side and from end to end.   

 

[ponypastor]

Hello, ponypastor,

I have had the same problem when  I tried one of the rubber style gaskets. No matter how snug the bolts were tightened I still had some fluid seepage. Our shop transmission Master tech refused to use them. He has repaired some transmissions where he had found stopped up filters and pieces of silicone sealant caught up in the valve body. This was a result of grease monkey and back yard shade tree mechanics using gobs of sealant trying to seal the rubber style gasket from leaking.

Use the cork Ford gasket C6AZ-7A191-B. Some parts houses may be able to cross that number to their version cork gasket. You could also try your local Ford or Lincoln dealer as some of them still have stock on that gasket even though Ford has discontinued it. It can also be found online at sources such as E-Bay by using the Ford part number. 

Thank you for the response and accompanying data with part numbers.

Very helpful.

Found exactly what I needed--Ford parts, gasket, filter and filter gasket as well with no shipping charges, and even cheaper that the rubber based gaskets at the local parts story. Appreciate your help.

Here's a peek at my 429 SCJ, freshly rebuilt after being off the road since 1975. 

 

[ponypastor]

A couple of things to do that will also help is to peen all the bolt holes and then to torque the bolts to 12 to 14 ft lbs.  Also tighten in a similar order as shown below alternating from side to side and from end to end.   

Thank you for providing the tightening sequence of the tranny bolts. Good advice. Appreciate it.

 

[Hemikiller]

The gasket the professional shops use is the Farpak composite, also called Duraprene. It's a rubber/fiber material that does a great job for a "one and done" installation. ALWAYS check your pan with a straightedge. If it's warped or severely puckered at the bolt holes and cannot be corrected, replace it with a new one.

https://globaltransmissionparts.com/ford-lincoln-mercury-c6-transmission-oil-pan-gasket-farpak-c6az7a191b/

Something to consider is to always torque the bolts to spec. My friends used to look at me like I had three heads when I would break out the torque wrench for valvecover, oil pan and tranny pans - but my vehicles never leaked....

 

[Don C]

The biggest reason for oil pan and transmission pan leaks is someone has over tightened the bolts, dimpling the pans around the bolt holes. Make sure all of the bolt holes are flattened and flush with rest of the flange.

 

[Gregaust]

A good rubber/cork gasket works well . Don't try to torque it . Just nip it up firm with 1/4 drive socket . Retorque a few times after a few heat cycles will be fine .

Trying to use a torque wrench will just bend the pan

Ensure pan is flat around the holes .

The Farpak gaskets are great with aluminium pans or late model steel pans with a ribbed face . not good on a steel c6 pan

 

[mustang7173]

All,

Several mechanics tell me the key is to let the transmission seal, "Vulcanize" . I have heard to let it sit over night. I had Ford change my F-150 Transmission fluid with the mechanic stating there were be a 2 to 3 hour vulcanization process to let seal. NO Leaks