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Bearing race fit in aluminum wheel hub...

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  • Bearing race fit in aluminum wheel hub...

    I'm reverse engineering a cast iron wheel hub to fabricate an aluminum replacement...should I copy the interference fit between the wheel bearing race and bore in the cast iron hub or revise it for the aluminum hub to compensate for different expansion under brake heat? Does it matter? I'm stuck using vernier calipers for ID measurement at the moment. Thanks for any input.

  • #2
    Ummm.... There's a limit to how much interference is actually beneficial. You want to stay in the elastic range of the housing. If you get too much interference, you'll just distort the aluminum pushing the bearing in, and you may well end up with less effective holding power than you would if you'd been less aggressive on the interference.

    I'm pretty sure Machinery's Handbook has specs for interference fits, although I can't recall at the moment if there are figures for aluminum. And it probably depends on the KIND of aluminum, as there are a gazillion alloys.

    How hot do you expect this thing to get? One thing you can certainly do is heat (gently) the aluminum and cool the bearing before putting them together, so you're closer to "operating conditions." The same caveat about overdoing it applies though; if, upon cooling, the aluminum gets streched beyond its elastic limit the "shrink fit" won'ts be as much of a shrink fit anymore.

    Another option may be one of the Loctite retaining compounds.

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    • #3
      What sort of bearing race. If it is taper roller don't be afraid of putting some press on it if wall thickness is sufficient, .001 per inch of diameter or just a tad more won't hurt. If this is a ball bearing it is different story altogether, press in a ball bearing more than a 1/2 thous and running clearance starts going away. Depending on operating temperatures you can go a tenth or 2 more. This press on ball bearing is not per inch of diameter, but total. Same approxiamate interference fit for a big ball bearing sas a small one.

      Machinery's has a section on class of fits for bearing bores.


      • #4
        When replacing the ring gear on a flywheel, I put the ring in the oven at 350, and the flywheel in the freezer. The flywheel goes in the night before, and the ring about an hour before. I would not do this with a permanently lubed bearing, and would put the bearing in the oven before turning it on if trying this. Mike