Rear Axle Seals and Gear Oil

[Liberty]

Greetings All,

I have a 1965 F-100, 352 V8, with a 4 speed, granny gear, 9 inch rear. I have noticed oil leaking from the right rear drum. I pulled the drum and the brakes are soaked with oil. I guess the seal is bad. After a little research, I believe the part number is 51098 (National Oil Seal - advanced auto). I am going to pull the axles soon. A couple of questions. Is the seal the type that has to be pulled out of the axle and not the one pressed on the axle shaft? Also, should the axle pull out by hand or will I need a slide hammer? And finally, I am planning to use Valvoline High Performance SAE 80W-90 gear oil. Its label reads it is recommended for hypoid differentials, conventional and limited slip. Is this oil suitable? According to the book 4 1/2 pints?

Thanks,
Liberty

[William-in-St George]

The wheel bearing will need to be replaced. This bearing is a press fit so you will need a press or take the axle to a machine shop. The oil soaked shoes will need to be replaced. After you have the axle out, look in the housing with a flashlight and you will see the seal. This is a messy job but fortunately one you will likely not have to repeat.

[Hazdri]

Liberty,

That is the correct part number.

The seal is "tapped" into the axle housing and not pressed onto the axle itself.

You might be able to pull the axle free by hand. If not, you can put the drum back on in reverse and loosely thread a couple of lugs on. A couple of pulls on the drum and the axle should come free. You shouldn't have to use a slide hammer.

80w-90 is fine IMO. 4 1/2 pints (2 quarts) should work. There should be a fill plug on the side of the head. Fill till the fluid comes out of the fill. Could be more than 2 quarts. Shouldn't be more than 3.

Couple of things to think about. Make sure the axle vent isn't clogged. If it is, that can cause a seal failure. Since your pulling the axles, check the bearings to see if you need to replace them. If its been awhile since the oil was changed and it looks bad and smells rancid, you ought to go ahead and pull the hoghead and give it all a good clean and start with fresh oil.

Hope that helps.

[Liberty]

Thank you all for your help. I did pull the axle and pulled the seal from the shaft. One thing I thought was kind of interesting was before I pull the axle I ran the car while It was up on blocks in neutral. The drive shaft and one of the axles turned as if it was in gear, even though it was in neutral. Does anyone know why that would happen? There's no problems with the transmission that I know of. Thank you again Rob

[bruceandersson]

Even though you are in neutral, there is still enough friction in the transmission to turn things. You should have been able to put a hand on the wheel and stop it, though then the other would turn. Non-posi axles only drive one wheel at a time. Some movement like this is normal, as long as you don't start moving. Check your trans oil level to be safe.

[Liberty]

Thank you, I will check the manual trans fluid. I also noticed the new seals are a little thicker than the old ones (5/16 old & 7/16 new). I guess they may indent some when they bottom out. Liberty

[Truckrat]

Hey liberty, saw you on chat Sunday night when you logged in.
Thought you might chat with us but you left without saying hello.
Come back next Sunday if you want. 8pm central time. TR

[Liberty]

Thanks, I have to figure out how it works! Liberty

[Liberty]

All, Thanks for your help! I was able to complete the oil seal repair. I have some notes I would like to post if I can figure out how to. No pdf or word attachments allowed? Thanks, Liberty