So I know for a fact that I am losing diff fluid into the right rear drum brake, and as of this morning, it looks as though I am also dripping into the drivers side. . I am not too terrible familiar with the seal set up, on the 10.25 rearends, and my question is, if its leaking fluid, then I need to replace the seals in the diff? not just the seals on the axles? I thought I read that somewhere, but after searching I cant find that post. I am pretty comfortable after all the amazing post on here, to do the outside seals, but not so sure about the ones in the diff. I recently swapped the cover out for the superduty cover, and everything looked really nice, no chips, nicks, no metal...gears looked really good, but I guess the seals have worn out???? Any info on what I should do would be greatly appreciated... also, any part numbers and best place to buy would be a great help. Hope this isnt too stupid of a question. Thanks again for all the help, I love this forum!

 

TheRe are no seals in the diff it's just the wheel seals that hold the fluid in. You need to check wheel bearings very carefully they are what typically causes wheel seal leaks along with buildup on the surface of the axle the seal rides on, I took emery cloth and polished that surface up on mine real nice and changed wheel bearings, no more leaking now

 

So your saying that should remove and replaces both sets of bearings and seals on the axles? Is there a specific kit that includes all of the parts needed? I have been reading the bronco f series manual for how to install and remove the axle shaft, oil seal, hub bearings...that is the way to fix these annoying leaks? unfortunately my auto-part stores around here are pretty terrible, and almost never have employees that have any idea about our trucks. So I look to you guys to be my guides. I really do appreciate it. Also, do you know the specific size that the axle lug wrench is? I should just buy it since I have now invested so much in my truck that I will never ever get rid of it!

Thanks again

 

Make sure that it is in fact from the hub seal, and not the wheel cylinders leaking.

 

I don't believe there is a kit but i will get you some parts info here in a second, and yes make sure it is gear oil and not brake fluid, you might wanna go ahead and do brakes drums, either turn them or replace based on wear while you got it all apart, also if your brake shoes are oil soaked you are supposed to change them as well, the gear oil soaks into them and they will not work like they should after that.

Rear Inner Wheel Bearing
National® 3994 - Taper Bearing Cone | O'Reilly Auto Parts

Rear Inner Race
National® 3920 - Taper Bearing Cup | O'Reilly Auto Parts

Rear Outer Bearing/Race Set
National® A38 - Taper Bearing Set | O'Reilly Auto Parts

Rear Wheel Seal
National® 370047A - Oil Bath Seal | O'Reilly Auto Parts

I believe those parts to be the right ones, make sure you check everything i don't have much time to double check right now

 

So I was looking at bronco graveyard, and they sell a inner, outter, and oil seal kit. But the kit oil seal diameter from there is different then the one that you gave me the link too.... so out of curiosity, which one is correct? And thanks again for all of the help. I am also 100% sure it is the diff fluid, I just changed the wheel cylinders, and pads 2 weeks ago, and both wheel cylinders are bone dry right now. also the fluid is purple, because I was silly and put royal purple diff fluid in (45 bucks gone....)

 

Tool need to remove the axle hub nut.

OTC Ford Rear Axle Locknut Socket OTC6601: Upgrade with the best Drivetrain Tools at Advance Auto Parts

 

Check that your axle vent tube (driver side, on the axle tube) is clear. If it's blocked, your differential could be holding pressure, and forcing lube out the seals.

On mine, the fitting on the axle was clogged badly enough to hold 90 psi or so from an accidental activation of my air locker. The seals couldn't hold that; oil spit out the seals. Oh, and very little rear braking power. New seals, new rear brakes... not fun.

So check the vent tube, so if it's blocked, you don't blow the new seals.

 

Thanks for all the help. I was a little confused, because there is a kit through Bronco graveyard that says it is all those parts, for a fraction of the price, and slightly different sizes... for the 10.25 axles... but I guess maybe that is for a different set up then the full floating rear-end we have? You guys have any tricks for setting the bearings other then a big socket? Thanks again