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Ball Bearings - Grades, Shielded vs. Open

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  • Ball Bearings - Grades, Shielded vs. Open

    I have been using open flanged ball bearings to support the rear axles in my scratch-built cars. I've been buying them off different vendors on eBay.

    But I suspect my eBay ball bearings may not be giving me top performance. Not surprising. My guess is these bearings find their way onto eBay because they are not first-quality. Bargain priced, yes, but probably for a reason.

    I have been buying open bearings instead of shielded on the assumption that any wear particles or contamination is easier to flush out of an open bearing. But I notice that slot car vendors tend to offer only shielded bearings. Shields help keep trash out of a bearing, but once its in, tend to keep it there.

    FYI, shields do not contact the inner race of a bearing. They do not contribute drag. Seals, on the other hand, do contact and do cause drag.

    I also notice that Professor Motor offers shielded ball bearings rated 'Grade 7'. Slot Car Corner lists bearings rated 'ABEC Grade 5'. Google tells me an ABEC Grade 7 is a higher precision bearing than a Grade 5.

    It is late in the game for me to be investigating ball bearing grades and characteristics, but better late than never. I'd like to hear opinions, hopefully backed by experience, as to which bearings are best.
    Last edited by HO RacePro; April 3, 2022, 10:45 PM.
    Ed Bianchi
    York Pennsylvania USA

  • #2
    We often upgraded stock bearings in 3D RC helicopters of 450 size or greater, to ABEC 5 bearings, which were more than adequate. We were told ABEC 7 bearings were avoided because the tighter the tolerances, the more likely debris would cause bearing seizure. For slot cars, anything over ABEC 3 is overkill. I have seen ABEC 7 and 9 bearings used in RC dynamic gliders.
    Last edited by Bal r 14; April 4, 2022, 11:00 AM.


    • #3
      ABEC bearings meet precision quality requirements. ABEC 1 are lowest, ABEC 7 are highest although you can get matched, certified ABEC 7 matched pairs or groups. The differences are measured in ten thousandth of an inch off center over an average rotation. Fit precision may also factor in, think slip on to your axles. As stated above ABEC 3 is probably as much precision as are community needs.
      Other factors, such as sealed versus open depend on how you will maintain the bearing, if at all. If you wish to oil your bearing you must use open (exposed) ball train. Some "bi" bearing exist that are sealed on one side. These can be useful if you wish to protect an open side from dust, while allowing maintenance oiling from the other side.
      Last , and most important, brand name bearings are higher quality. US, German, Japanese are likely to last and perform better, but for our use, probably doesn't make too much difference.


      • #4

        Those "bi" bearings sound attractive. Would they be available in a flanged design? My idea would be to install them at either end of an axle tube, shield side out. Then have holes in the axle tube to allow oiling.

        I would be very interested in recommendations as to where to buy bearings. To date I have used eBay for generic bearings and McMaster-Carr for industrial quality bearings. But it looks like some of the bearings you mention would only be available from specialty vendors.

        Ed Bianchi
        Ed Bianchi
        York Pennsylvania USA


        • Aptosc6
          Aptosc6 commented
          Editing a comment
          McMaster-Carr has an extensive collection of bearings at reasonable (fair) prices. Quality is very good and they use high quality manufacturers. I'd start there.
          You can make your own "bi" bearings. Use an exacto blade and pry one of the shields off of a sealed bearing. Easier than you might think.
          Cheap guys like me use Chinese bearing because they are cheap and these are only toy cars : )

        • HO RacePro
          HO RacePro commented
          Editing a comment
          I like the idea of removing one shield via X-Acto knife. I'll try that!

      • #5
        Ed,.......PCH Slot parts sells a wide range of bearings from GRW and Koford ( Abec 7's, and for the type of cars/motors you are running, completely unnecessary) to Abec 3's from Chi-Town at 5pr. for $25. I know lots of racers using these Abec 3's and they are all quite happy with their performance/longevity.

        You can also try "VBX Bearings" who manufacture/sell a very very wide range of bearings (in various qualities) for all types of applications. I have used many VBX's in the past, and have been pleased. They do make some "slotcar" specific single flanged shielded bearings in 3/32 x 3/16........these are ABEC 3+.

        Worth mentioning that most (if not all) quality 3/32 bearings will require a 3/32 axle/drill blank......slot-it axles will not fit.

        Chris Walker