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Jake von Slatt sent us a link to this nifty “legendary” automotive tip for removing old bearing races from an aluminum axle hub. There’s no way of knocking or prying them out. But if you weld a bead around the inside of the race, when the weld cools, it’ll shrink enough that it’ll come away from the hub, so that you can install new bearings. Cool! I guess this technique would work in other situations where shrinking a metal part would free it from a housing.

A neat trick for removing bearing races

Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor for Boing Boing and WINK Books. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.


  • Travis

    When I change the rear wheel bearings in my 1991 VW Golf GTI, I don’t have access to a press to put the new races in, so I took the old races and notched all but the very bottom of the thickest side. This way i can use the old race to pound the new one in mating the two thinnest sides. When the race is fully seated, the old one pops right out :)

  • Fred

    Since that is an aluminum housing and a steel bearing I would first try heating the whole assembly in an oven to see if the aluminum expands enough to let the bearing fall out.

    The welding trick is something to save for a steel bearing in a steel housing.

  • trialex

    @Fred –

    The housing would expand in every direction though – including INWARDS to make the fit against the bearings TIGHTER.

  • Richard

    On my ’55 Stude the flywheel is replaced by heating it up till it falls off. Then heating up the new one till if falls on. No other mechanical fastening required.

  • Anonymous

    All you have to do is heat the steel–then, as the steel cools, the heat will be conducted into the Al–causing it to expand and let the bearing fall out. (It expands outward more than inward. Really, it falls right out.)

  • NickH

    @trialex

    You’re not correct in saying that the hole will shrink. I had to think about it a bit, but I remember from my physics classes that the answer is tricky. When you heat a metal, you’re increasing the distance between the molecules. Lets work through it… There are two choices: the hole increases in size, or it decreases.

    If the hole were to decrease in size, the molecules on the outside of the donut are getting further apart, but the molecules on the inside (next to the hole) are getting closer together. Wrong answer.

    When the hole increases in size, you get the correct molecular behavior: the molecules on the outside of the donut are further apart, as well as the molecules on the inside. This is the correct answer. Neat, eh?

    More at metafilter:
    http://ask.metafilter.com/10917/Heating-Metal

  • Anonymous

    All you have to do is heat the steel–then, as the steel cools, the heat will be conducted into the Al–causing it to expand and let the bearing fall out. (It expands outward more than inward. Really, it falls right out.)

  • Alex Barclay

    http://www.parker.com/literature/download/Aircraft%20Wheel%20&%20Brake%20Manintenance%20Manual,EN.zip
    Look at main300.pdf, page 317.

    You’ll see the procedure for removing the bearing. Welding the cup is definitely bush league as the extreme expansion of the cup will overstress the soft alloy that it’s installed in. The wheel bearing lands are one of the highest stress areas and you’re planning to stress them further and potentially add some cracks? No thanks!

    Alex.

  • Luke

    Have you ever thought of producing this remover and selling it?
    Just a suggestion.