68 C6 transmission differences

[Mcdizzle83]

I tried replacing the output shaft seal on my 68 with a 462 and C6 trans. The seal that I ordered is smaller than what was removed. I did some research online and it seems like most seals are consistently smaller than what I need. I attached a picture of both seals for reference.

Does anyone have knowledge that the C6 trans had different variants over the years?

[Lee]

This is from a 1969 Chilton parts and labor guide, and they are all the same. Maybe it’s a much later C6, don’t know if those are different.

Nope. Timken says they are all the same to 78. Sure it’s a C6?

[Dan Szwarc]

The C6 parts catalogs are wrong.

The tailstock of the 66-69 C6 in a unibody Continental is different from all following years and ALL other applications.

66 to 69 Extension Housing Oil Seal is C6VY-7052-A for the Continental Only. No ID given.
Here's the Rock Auto Listings. Both are OoS.

66-69 Continental C6 Extension Housing Oil Seal

Screenshot 2024-02-16 at 3.13.08 PM.png (10.41 KiB) Viewed 184 times

70 to 72 and up is D5AZ-7052-A. Listed as 2-3/4" ID.

[Lee]

The extension housing bore for a C6 is 2.5”, and 3.06” for a PCA. Check your pan bolt pattern, it might not be a C6. The one you removed doesn’t have a metal “ lip” like a C6 seal. The PCA does not have that lip.

[Dan Szwarc]

The extension housing bore for a C6 is 2.5”, and 3.06” for a PCA. Check your pan bolt pattern, it might not be a C6.

It most likely is. Other C6s don't fit without major mods. There are major bellhousing differences.

Here's a seal on Ebay for $15:
https://www.ebay.com/itm/204287788056

Verify the application by cross-referencing.

[Lee]

The C6 parts catalogs are wrong.

The tailstock of the 66-69 C6 in a unibody Continental is different from all following years and ALL other applications.

66 to 69 Extension Housing Oil Seal is C6VY-7052-A for the Continental Only. No ID given.
Here's the Rock Auto Listings. Both are OoS.
Screenshot 2024-02-16 at 3.13.08 PM.png

70 to 72 and up is D5AZ-7052-A. Listed as 2-3/4" ID.

Good catch Dan. But I did find that when I ran that part number, Rockauto gave me SKF 22382, in stock, and confirmed to have the larger 3” bore.

[TonyC]

RockAuto also thinks that 460 valve lifters fit a 462 engine. Don't trust them.

Dan's right. The C-6 internals are the same for all applications, but there are unique differences in the clap-door applications for components around the core internals. My last rebuilder made the same mistake during the rebuild 11 years ago, but they found that out and got the correct seal from Baker's Auto. As Dan has already indicated, Baker's replacement firm, Old Car Clearance, happens to be offering the correct seal on E-Bay now; I've been pondering the thought of getting one myself, in case I need one in the future. Go there.

---Tony

[frasern]

Here is something on my garage floor that I sometimes trip over, it is from a '66, 2 1/4 inside, 3 1/4 out. My other ones have a rubber shield (boot) like yours, this one was rebuilt by an authorized Ford rebuilder. I would think any bearing supplier can match up the size, If you can live without the boot.

Lets face it, Lincoln transmission output yokes are just weird, that rectangular roller bearing is pointless, all it does is make things unique to Lincoln, and this is one of them.

[Dan Szwarc]

This version doesn’t have a booted seal. It was never available.

There actually was a separate yoke boot originally, but they’ve all disintegrated over the years and no one makes reproductions and they are not really needed.

[frasern]

You made me look!

[Lee]

Lincoln transmission output yokes are just weird, that rectangular roller bearing is pointless, all it does is make things unique to Lincoln, and this is one of them.

It would be hard for me to believe that Ford would spend the extra money for something that wasn’t even visible, unless some engineering group proved that it measurably reduced noise, vibration, harshness or wear.

My guess: that 7 degree drivetrain slope to get the (comparatively) small transmission tunnel gave a pretty severe angle to allow easy fore and aft movement of the driveshaft, and perhaps they found that normal splines would gall or bind. The double Cardan joint may have helped with power transmission. But I don’t think it helped reduce the binding effects of that angle.

[TonyC]

I hadn't thought of that; maybe that could be. I have to agree, there had to be a reason for that oddball output-shaft/slip-yoke design. Even the items that turned out to be flawed designs were conceived for reasons. I certainly wouldn't call those needle roller bearings "flaws"; they work, and they hold up quite well (24 years and more than 300 kilomiles have shown me that). Somebody once told me that NASCAR runners used that design, possibly for all those reasons, though I never found any evidence to confirm or refute that claim.

Maybe the boot Fraser showed was meant to help contain any drops of fluid from escaping. My transmission always shows a Class-1 or Class-2 leak at that spot: Not enough to stain the floors, nor enough to require a top-off on a regular basis; but it's visible. True, though, not a critical nor even substantial need, as I have no plans to subject Frankenstein to the nitpicky whims of German inspection stations.

---Tony

[frasern]

They could have used a fixed front yoke and a slip spline in the driveshaft, as trucks have always done, for a fraction of the cost. The auto industry is full of copycats, how many others have copied this?
I am not denying it's reliability, and I'm sure it has a NVH rating a millionth of a point lower, but that still doesn't make it any less weird.

[Dan Szwarc]

You made me look!

One learns something new every day!

I was looking for a post that mentioned this and couldn’t find it. Thanks for looking!

[1Bad55Chevy]

What years do the C6 have that crazy output shaft?

Our Mark iii does not have the original transmission in the vehicle but it looks to have the correct driveshaft.