Ford Powerstroke Diesel Forum banner

Rear Diff Pinion Seal

3K views 7 replies 4 participants last post by  99BEIGEPOWERSTROKE 
#1 ·
Ok well I have a class 3 leak on my rear diff pinion seal. Now I heard something about having to preload the pinion when you replace the seal. Can someone explain this too me. I plan on just removing the driveshaft, remove pinion nut, remove yoke, remove seal. Install new seal, install yoke, Install pinion nut to proper torq spec., Install driveshaft. Then remove the diff cover drain the fluid, flush the rear diff out. Clean the gasket off the rear diff cover, place new gasket on rear diff cover. Install rear diff cover, then fill with Gear Oil to proper level.

Now is there anything I am missing. Besides this pinion preload I hear about.
 
#2 ·
if you are reusing the original crush sleeve, somewhere between 8 and 16 inch lbs of preload i think is sufficient , you need an inch pound torque wrench
to check it , if you dont have one , be very careful and you can get a feel for the amount of preload before you pull it down and then gradually tighten it back to the same feel when going back, ive just aquired a feel for what it should be but thats hard to describe without showing somebody , just make sure its not to tight
 
#3 ·
I got a full set of torq wrenches, inch pounds and ft pounds. So that is not a problem. I will read up on this when I get home. It is nice to have a repair manual for the truck. I was just trying to get a grip on this preload thing.
 
#4 ·
you should be set then , like i say , if you have someway of reading up on it that may help, the main thing is not to tighten to tight , you can go tighter but if you crush the sleeve to far you cant back up and regroup then
 
#6 ·
IIRC theres one nut on there that you need some ungodly amount of TQ on, like over 100ft/lbs... I could be wrong b/c Scuffy didn't mention it.

As for the rear diff, I'd personally remove the diff cover and drain it first. Clean the mating surfaces up and the diff cover real good. I use BrakeKleen, but don't SPRAY it IN the diff housing, use a rag soaked in it to help with the mating surfaces. While you have the cover off, sand the crap out of it and then repaint it black, or silver (fake after market diff cover) LOL.

If you're on level ground just refill with synthetic until it dribbles out. If you buy mobil 1 like I did, you won't need any L/S additive if you have a L/S. Also, because of the angle you'll be at with the rear diff and fuel cell in the way (unless you lift the truck from the frame), you'll most likely want a small pump with a hose to get the oil back in... otherwise when you get down to the last 1/4 of the bottle you'll find you're getting more on you then in the diff. This has been my experience doing it about 3 times or so now, and a 7 dollar pump makes it simple for me. There is probably an easier way to do it but that's the best way I've found for it! :D
 
#7 ·
when you pull the yoke off ,then you have the seal, right behind the seal there should be a slinger looks like a wide shim, down below that there is the front pinion bearing , the front bearing sits against the crush sleeve which sits against the pinion gear
 
#8 ·
How much play should be in the yoke? I have a driveline vibration and had the driveshaft rebuilt cause the slip spline had play in it but its still there some. I think it may be the yoke in the rear differential. I can grab a hold of it and move it back an forth a little bit by hand when the truck is in neutral. Should I be able to move the yoke in the rear axle with my hand? O and the seal is not leaking.
 
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