[rotorwrench]

I've never used the seals on the inside of the bearings due to the possible interference between the slinger ring (baffle) and the seal. If a person is going to use the seal, about the only recourse is to fabricate a shim the thickness of the baffle but with only enough diameter to act as a shim. This would be a way to get the proper dimensions of the stack up without a conflict between the baffle and the non-original seal.

I work on helicopters that use grease seals that are removable on both sides. Depending on the bearing size and application, they have varying schedules for inspection and reservice of these greased rotating ball bearings but all are required to be inspected and reserviced at 24-month intervals with a shelf life grease interval of 4-years before re-service. I would not use a sealed grease bearing in a transmission for this reason. A seal in the outside is fine but a proper baffle on the inside is there to insure that the gear oil will lubricate the bearing. This is the same reason I use phosphor bronze pilot bushings in the flywheels. Sealed bearings may last a long time but there is no guarantee that the lube inside them won't break down and lose it ability to protect the bearing any more than peoples perceived worry that metal particles with hurt the bearings.

On one particular helicopter I maintain, we have to inspect and lubricate bearings that are exposed to outside elements more often than others due to the tendency for water to get into them through those rubber seals. Owners don't like the grease on there so they would wash the machine with a pressure washer to get the old expelled grease off. With water inside the bearing, they corrode and can fail if not inspected more often. Condense is another problem on some bearings. It makes a person scratch there head on just how water can get in there but it does. With seals in place, it can't get out so it stays in there and mixes with the grease.

Due to all of this experience, I'm a firm believer that Ford knew what they were doing when they designed and built them the way they did. It was the most reliable way to make things last as long as they could for the technology of the time. Now days, planned obsolescence tends to keep thing wearing out at about the same rate they always have with very few exceptions.

All gear boxes make metal. This requires that there be a scheduled draining and refilling of the lubricant in there. Warm the component up to get the crud in suspension then drain it out. Do it as often as Ford recommended or do it once ever 12 or 24 months but do it. Your engines, transmissions, & axles will last a lot longer that way.