This is a 1990 Ford F150, 4WD 5 liter engine Manual Trans.
I was just doing a little work on the parking brake on this truck when I noticed that there is a rather large puddle of rear end lube on my garage floor, coming out of the oil seal behind the flange where the driveshaft connects. (The REAR differential).
I just replaced one of the universal joints on that rear drive shaft, a few months ago. So, getting off the driveshaft is no problem. However, I have never replaced a grease seal on a differential, although I've replaced several of them on the rear of automatic transmissions, as well as many in brake rotors.
I am asking about this because I am not sure if this is something I can do at home, or should I let a mechanic do it? (I try to do as much of my own work as I can, but there are limits, and one of them is working on the ground under a vehicle).
I looked at a photo of a Ford differential on a website, and see how it all goes together. Basically from what I see, I remove the U-bolts on the drive shaft univ. joint, and get the shaft out of the way. Then I remove that large nut in the middle of the flange. Then, I (somehow) take the flange off, and change the seal. It looks easy enough, but how hard is it to remove that large nut? I'm using hand tools, although I do have an impact air wrench, but my compressor has a hard time keeping up. I guess what I am asking is Can this be removed by hand, and assuming I block the wheels, (leaving the truck on the floor), can I remove it without the differential turning? Are the threads on the nut a standard thread, or a reverse thread (CCW)?
Assuming I am able to get the nut off, how do I get the flange out. Does it just pull out, possibly with a little tapping and leverage from the rear or it? Do I need to mark the spline teeth so it goes back the same, or is there a key or larger tooth or groove?
Finally, will anything fall out (such as bearing), or will the spline drop, push inward, or any other unexpected things?
I'll assume the oil seal is just the common type like on the automatic transmission rear shaft, and I pry out the old one, and I carefully tap in the new one, using a block of wood against it. (yeah I know they make special tools for that).
That about covers it. I'd greatly appreciate any advice about this. I dont want to get into the job and find myself unable to do it. I noticed on that website, they call it a "pinion seal", not a grease or oil seal.
One other thing. On that website they show an 8.8 and a 10.25 differential. What are they measuring? I know they'll ask me that when I go to get the part. Will I need a model number too, or is the size enough? If I need a model number, where is the number or tag on Ford differentials?
Sorry for all the questions, I just like to know what I'm doing before I get out the wrenches.
By the way, do all Ford differentials take the standard 90 weight lube, or do they need something else?
Thanks for all help.
F.D.