1971 Roadrunner pinion seal?

[glh55]

HELP, I have a 1971 Roadrunner that someone has changed the differential. It was leaking oil so, I decided to change the pinion seal. I pulled off the companion flange and there was no seal at all. The dif is a 741 but none of the seals I have purchased for it fit. The shaft is 1.875 dia. and the hole the pinion comes out of is 1.95 inside dia.
Can anyone tell me what kind of seal I need?

 

[silversedan]

call DR. Diff. or google him if you don't know him.

 

[R413]

A 489 is 1.875 diameter, or 1 7/8
A 741 is 1.375 diameter or 1 3/8

These both take the same pinion seal. SKF 18078

A 742 is a 1.75 diameter or 1 3/4



Look it up on rock auto and you can see they list the seal by the case number or the decimal numbers above. Not the fractional numbers.

 

[R/T Boy 67]

There is something wrong with the dimensions you stated. If the hole in the housing is 1.95" then there is something in there that needs to come out. The 741 and 489 housings take the same seal and should be easy to find at your average auto parts store.

 

[R413]

Might be the outer ring of the last pinion seal still in there.

The diameter of the yoke to the pinion seal is 1.875, the seal bore in the case is is 2.825 for 741 and 489 cases.

 

[Ernie ingling]

Think the metal from old seal still in diff

 

[Mick56]

While you're down there, check the axle vent. They can get plugged up, and create enough pressure to make the seals leak.

 

[glh55]

Thanks for all the replies. I called Dr. Diff. The old seal was still in the housing. The leather seal was gone and there was enough crud on the housing that I could not see the old seal. I removed the old seal and installed a new one. All is good now.