The original inner hub seals were made of leather. One of Fords suppliers was Chicago Rawhide. Quite often the original seals are found still in place during an overhaul. The letters CR are found stamped on the side. Most of the leather is usually deteriorated.
It made sense to install them such that when the axle slid into place it did not fold the leather back on itself.
Modern replacement seals are made of neoprene. Supplier's literature say to face the taper on the seal toward the lubricant. There is a taper on both sides of the seal and it is not specified what lubricant they are talking about, the oil in the banjo or the grease that is pumped into the rear wheel bearing.
The seal is a grease seal, not an oil seal. Its purpose is to prevent the grease that is pumped in through the grease fitting on the rear backing plate from migrating down the axle shaft toward the differential instead of going outboard to the rear wheel bearing.
People continue to argue about the purpose of the seal and which direction to face it. If you have ever pulled a rear end apart that had the original shot seals installed and an owner who religiously pumped grease into the grease fitting on the backing plate you would find that grease has centrifuged around the axle an inch thick and is as long toward the differential as the owner's frequency of pumping grease into it.
I don't think it matters which direction you face the seal, either way it will snap into the slight groove in the axle and it will do the job.
It is best to pack the rear wheel bearings when you have the drum off and forget about that grease fitting. Ford eliminated it during the early V8 years.
Tom Endy
