i was told that if you use those sealed bearing you don't need to use the axle seals inside the tubes. anybody know if that is true?
Leaving that seal in with sealed bearings won’t hurt anything, actually a little better! Just make two seals on the axle! Bones
Sometimes the sealed bearing will hit the inner seal preventing it from sliding in all the way, I remove them, add a skim coat of Right Stuff rtv on the housing where the O-ring sits and have never had an issue.
Just be careful installing them! I put a small dent in the seal on the bearing for my '56 Olds rear in my Willys and didn't give it a second thought. Several months later the car came up with a nasty grinding sound driving home from a 200 mile trip to a rod run. I checked all 4 wheel bearings and of course it was the last one I checked. The bearing was nuked, only had 3 balls left holding it together, zero grease obviously. The dent in the seal evidentally started wearing on the inside, depositing metal shavings in the race, dooming it to fail.
I have not seen a sealed ball bearing in a Ford 9" differential NOT have an inner seal. The inner seal prevents the oil from washing though the bearing. Yes, they are a sealed bearing....but the lube can pass through the bearing and eventually causing a bearing failure. Caution must be used not to damage the inner seal and also to locate it at the proper depth.
From what I have learned recently the inner seal goes in until it rests on a shoulder in the tube. Most all the oring bearings for the 9 inch 28 spline with a 1.531 shaft ID are from the after market as far as I can tell. I removed a defective RE508ER that had the oring which was sloppy. It had been installed by a previous owner. Replaced it with a SKF 88128R.
It is true that those are sealed bearings. However, if the seal is not in place, axle lube can leak out through a vent hole under the bearing retainer and get on your brake shoes; not good.