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Norton wheel bearing NM.17721, aka 4203

Discussion in 'Norton Commando Motorcycles (Classic)' started by Anonymous, Aug 1, 2003.

  1. Anonymous

    Anonymous Guest

    Anyone have a substitution for the deep-groove double-row wheel bearings (1 fore, 1 aft) NM.17721, aka 4203 in a double-sealed version? I understand there may be a substitution that is 1.5mm wider. Thanks!
  2. dynodave


    May 28, 2003
  3. docrecon


    Sep 30, 2003
    Re: wheel bearing

    Thanks DynoDave! Yeah, I'd run across the Old Britt's page and that's helpful, and for now I've decided to take your approach; I bought new single-row sealed bearings from a local bearing supplier as they're not expensive, if my double-rows test out OK I'll repack and go w/ 'em, otherwise I'll go to the sealed ones, Old Britt's prices aren't too bad and I've got the equipment to do the mod.

  4. bill


    Jun 1, 2003

    try a 5203 at your frindly bearing house

  5. Anonymous

    Anonymous Guest

    Re: bill

    OK, thanks Bill! Both the 5203 and 5203-2RS are 17x40x17.5 vs. the 4203's 17x40x16, thus being 1.5mm wider than the standard bearing. So, the mod would have to be performed to "both ends" to get 'em to work, but w/ the 5203-2RS you'd have a sealed bearing.


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