Subscribe

WHY DO WHEEL BEARINGS FAIL?

Return to: Caravan Clinic

Come chat with us in the forum. Click here to register an account or if you are already registered click here to log in.

  • Profile Photo
    André Gouws
    Participant

    We have a 2015 Jurgens Classique which we bought toward the end of that year. All services were done on schedule. Our first long trip took us up the Garden Route, after which we headed through the Free State and Gauteng to Limpopo.

    A service was due when we approached the town of Brits, and we took it to a local agent who kindly fitted us in at short notice. A wheelbearing service was included in this service.

    Then we visited the Kruger National Park, and made our way back towards home in Cape Town.

    While we were driving through Oudtshoorn, a wheel came off. Fortunately, we were travelling slowly, but the caravan had to be taken in by flatbed trailer for repairs in Mossel Bay.

    The wheel bearing had collapsed and showed signs of severe overheating.

    The question now arises as to how frequently caravan wheel bearings need to be repacked. Our tow vehicle, a Ford Ranger, has almost 250 000km on the clock and has never had wheel bearings replaced or serviced.

    Many thanks for your much-appreciated Caravan Clinic.

    Attachments:
    You must be logged in to view attached files.
  • Profile Photo
    Godfrey
    Godfrey on

    Could it be that trailer wheel bearings endure greater strain from fishtailing action? Or, the more immediate question: are these underspecified for the job?

     

    Profile Photo
    Godfrey
    Godfrey on

    Funny thing − I have always been a believer in Timken bearings, so I googled them, thinking they were best of British, but I see they are made in China!

    We took your issue up with some caravan dealers, an axle manufacturer, and a bearing supplier, who comment as follows:

    1) The experts at Bearings International say that heat is the biggest enemy of a wheel bearing and that heat build-up can come from various sources such as a damaged spindle or carrier in which the bearing fit is loose, and the bearing starts turning in the carrier. Or it can be too much grease; even in boat trailers where the bearing space is packed full of grease to keep water out when submerged at launching time, the thickness of the grease causes friction, melting and ultimately failure. A give-away is blackened grease, which is a sign of overheating.

    2) A faulty manufactured wheel bearing should fail immediately, and not only after 400 km. Others may fail over a longer distance, too − or it may be that it was a cheap bearing to start with.

    Then there are several fitting criteria that apply:

    1) It is important that the person fitting the new bearings has meticulously cleaned out the inside of the wheel drum as well as the spindle, prior to fitting new bearings. Any dirt present will contaminate the grease and the bearing.

    2) When one is replacing the bearings, the oil seal at the back of the hub must also be replaced. This prevents dirt from entering the bearing.

    3) Before the bearings are placed into the hub and onto the spindle, they must be lightly greased. The emphasis is on ‘lightly’. The person should be wearing a spotlessly-clean latex glove, on which there is no trace of oil, petrol, solvent or dirt, as these will compromise the bearings’ performance and life. The grease must be worked into the bearing so that it has a light coating − never over-fill or over-grease inside the hub as this will eventually leak out, as can be evidenced by ‘runs’ from the bearing cap, or the back of the wheel.

    4) Never use a sharp instrument to remove old bearings, as this may damage the bearing surface and create a groove for grease to escape.

    5) The cap in the hub should be replaced after it has been removed a number of times. Due to the nature of removal, it becomes loose in the hub and can allow grease to escape and dust to get in.

    6) If the brakes are set too tight, these may bind and cause the bearings to become very hot and cause the grease to melt away from the bearing surface. A common cause of brake failure is that the hand brake has not been fully released and the bearing has run hot as a result. Binding brakes generate enormous heat and, as stated, heat is bad for bearings.

    Generally a hand brake should require only three clicks from the top of the ratchet to release, and not the bottom of the ratchet, for it may bind and overheat the brakes and bearings, causing the grease to disperse and the bearing to run dry.

    7) Don’t re-use the split pin that secures the Castle-nut, as this introduces other problems − as does over-tightening or having too-loose a Castle-nut. While wheel bearings seem like an easy DIY servicing, this is best left to an expert for the above reasons.

    Your experience, however, brings home the necessity of carrying a complete spare set of bearings and seals, as the alternative may be needing them on a Sunday afternoon when one is between nowhere and home, and that is not an experience one would like.

    Most caravans have Al-Ko axles. We have a list of bearings attached, one of which may fit your caravan; but it’s best to ask a dealer, as sizes and specifications vary.

Viewing 2 replies - 1 through 2 (of 2 total)

Come chat with us in the forum. Click here to register an account or if you are already registered click here to log in.