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Posted by David Sherman [72.47.9.228] on Wednesday, December 15, 2010 at 14:34:12 :
I've just replaced all the seal and bearings on my sno-cat and realized that there's a problem with the new seals there. They have the light-weight Dodge corporate axles used on 1/2 ton trucks, bigger Chrysler cars, etc in the 1950s and 60s. This is a semi-floating axle with only one timken bearing. It's recognizable by the unusual 3-prong castellated nut in the hub.
There's an aluminum bearing retainer and seal holder that goes over the end of the axle shaft and bolts to the housing, with shims under it to set the bearing pre-load. I was finding I needed to add lots of shims and gaskets to make it seem like it fit. It turns out that the problem is the new seals, which are the modern kind with the double rubber lip and the little spring around it, have their inner edge flush with the inside edge of the bearing retainer and they hit on the inner bearing race and cage when you bolt it all together. The original seals appear to have been simply a disk of felt or leather in a metal carrier, and they set a good ways farther out on the shaft where they didn't hit on the bearing cage.
If anyone here has replaced the seals on that kind of axle, I'd sure like to know how you dealt with this problem. If the retainer was thicker, I could probably cut the seal pocket .070 or so deeper and that would be enough to keep the inner lip of the seal from hitting the bearing cage and inner race, but there isn't enough room for that. It's not simply a matter of adding shims, because then the retainer would not be far enough inboard to actually retain the outer bearing race. That would let the outer race back out .070 or so from the axle housing causing the bearings to be very loose and letting the whole shaft work back and forth within its housing which would wear everything out quickly.
I looked up the modern seal number at Rock Auto and they're showing it as the part they sell for that axle. It's "correct" in the sense that it's the right overall thickness and the right ID and OD, but it doesn't run on the shaft in the same place and it sticks further inward than the original. It seems like everyone must be having problems with this. To be safe, the inner edge of the seal really needs to be .100 back from inner face of the retainer so that the seal lip will never rub on the bearing cage no even if no shims or gaskets are used.
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