8.8 differential

[jdavidsmi]

While I was waiting for the battery to charge, see the on going electrical issue thread. I thought now would be a good time to replace the leaking pinion seal.

Once I removed the pinion nut the yoke could be pulled off with my hand. Is that normal? I thought it should have been a lot tighter.

Both the yoke and pinion have 30 splines

Also in 84 was a flange was used instead of the yoke? I have seen pictures of both, but no clue as to when each application was used.

last question is, if the axle vent is plugged, would or could this cause the seal to start leaking? the seal I replaced looked almost brand new.

[Gary Lewis]

The seal should be a press-fit. And a plugged vent will cause a leak somewhere. Either of the axle seals or the pinion seal, or all of them.

I'll have to check on the flange question later.

[jdavidsmi]

Thanks, while I'm at the parts store I will pick up a new one, fast and easy fix.

[PetesPonies]

Most times the yoke is much tighter, but if the splines look good, just feel lucky.

[Gary Lewis]

I'm not sure I understand the "flange" vs "yoke" question, but it isn't something I can answer from the catalog.  That's because Ford calls it a flange, with the generic part # of 4851.  So, whatever goes there is called a "flange" in the catalog even when most of us would call it a "yoke".

[Nothing Special]

Some diffs (and transfer cases) have one side of the U-joint yoke as a part of the piece that is splined to the pinion shaft (output shaft for a t.case).  Then you use U-bolts to attach a single Cardan U-joint (or 4 bolts to attach a double-Cardan) to the yoke.

Others have a flat flange splined to the pinion shaft.  In that case the U-joint yoke will have a corresponding flat flange that attaches to the flange on the diff with (I think) 4 bolts.  Those U-joints have all 4 caps pressed into the yokes (like a front axle U-joint) rather than having U-bolts.

I can't say I'm 100% sure, but I thought Ford stayed with yokes well past 1984.

[Gary Lewis]

Thanks for the explanation. I kinda thought that was the case. But it didn’t matter as far as the catalog is concerned as both are called a “flange” by Ford.

[jdavidsmi]

This is what I called the yoke


And this is what I called a flange


I hope its ok I got the flange picture from the fourwheeling website.

[Gary Lewis]

Absolutely ok to find pics elsewhere and share them here.  I do it all the time.

And, that's what I assumed you meant by "flange" and "yoke", but wasn't sure.  Unfortunately, w/o part numbers I can't tell when one was used vs the other as Ford calls both of them a "flange".  

[PetesPonies]

Yes, the 8.8 uses a different driveshaft attachment as shown in the pics.

[Bruno2]

How tight the pinion nut is has everything to do with your pre load. If it was hand tight that probably means your bearings are out of tolerance and may be needing a rebuild pretty soon. Also, whenever the pinion seal goes bad is tell tale signs of the bearings having a lot of play in them causing the shaft to woller the seal out.