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Wheel Bearings and Failures

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  • Wheel Bearings and Failures

    I don"t know what it is with wheel bearings but they sure don"t seem to get much care, or their installation is badly done.After I fixed my friend"s rotor bearing and he took it for some hops, then a check of the head without the rotor, then a proper circuit, we discovered his nose wheel bearing had collapsed on one side. The rotor head bearing was fine, but the wheel bearing was cactus :-(We removed it and found that the pocket bike wheel ran on two ball bearing races, both sealed units. It was quite simply mounted on a 10mm shaft with the forks pinching in on the inner race and the outer race pressed into the wheel hub....BUT!!!!!There was no, repeat, no spacer tube on that shaft to keep the bearings from being undesirably loaded axially by the shaft nuts being tightened up onto the bearings :-O

  • #2
    Good post Nick, they are very important ......


    • #3
      couple of service bulletins for Black Max on Recreational Flying website.
      Remember: no matter where you go, there you are


      • #4
        Thank you Ross & Murray


        • #5
          One more thing about wheels that people often overlook, is balance.... The small tubes we use, or tubeless stems if no tubes used, usually make the small wheels out of balance. So what I hear you all say?.... well, gyros land pretty slow, so not really an issue there, but on takeoff, often the little wheels are asked to do 40kmh..... sometimes more.... so just as you lift off, the out of balance wheels are flat out, then suddenly off the ground spinning like mad.... this is hard on bearings and we all know what nose wheel shimmy feels like.... often the nose wheel is smaller, so it is spinning even faster....Ok, so jack your nose wheel off the ground, spin it and look for the tyre on the rim properly (center of tyre not rising and falling as it rotates) If it is more than a couple of mm "out of round" mark the high spot, let the air out push the tyre off the bead, put soapy water on rim, put a few pounds of air in so it seats lightly on the rim, spin, look for high spot again and push and manipulate the tyre to get it so there is the least run out.... than put your normal air pressure in. Spin the wheel and listen for dud bearings and put side load on the bearings each way to see if there is any play anywhere in the axel or bearings. Then spin the wheel a few times in a row and see where the wheel stops by itself each time.... 10 - 1 it will always stop with the valve stem down.... and sometimes it the wheel will actually go past valve at 6 oclock, then go backwards to 6 oclock,, that is seriously out of balance..... from a tyre shop, buy a strip or 2 of stick on wheel weight... snap off a couple of squares and without peeling the sticky paper, tape on a square each side of the rim, spin again, if still valve down, tape on another square each side, spin again, now if it stops weight down, you have too much weight.... snip a corner off each of one weight on each side, spin again...... if it stops with the weight and stem at 3 oclock, 9 oclock, and you spin it over and over and it stops in any old place, it is pretty well balanced, so mark where the weights need to go, un tape them off the rim, clean the rim with some meths (not metal cleaner or polish) sit the weight on 2 drill bits lead side up and tap with a ball pein hammer so the weigh gets the aprox shape of the rim, then peel the sticky back and stick on permanently where it needs to go. Then spin the wheel a few more times.... if you think the weight might be a bit much, drill away some lead a little at a time with a 3/16" drill and spin again. You want the wheel to stop any old place every time and it shouldn"t stop spinning and run backwards at all..... the bearings should sound "happy" no change of sound or vibration as it slows....Do the same with your main wheels, Jack up and spin..... I bet you are surprised how out of balance they can be, but the size of the wheel means a couple of grams is a lot, especially at speed. Sure it sounds pedantic, but that is my middle name.... you will notice the difference, I bet.