Auto locking hubs

Discussion in 'GM Powertrain' started by tinman, Jan 3, 2010.

  1. tinman

    tinman New Member

    Hello Everyone-

    I just signed up as a new member and I'm looking for some diagnostic help. I am the proud owner of a 1990 GMC Suburban 4X4 3/4 ton. It has Auto locking hubs. Lately when coming to a stop I hear and feel a clunking coming from the front end. And yesterday as I was leaving the house down the street as I applied the brakes the clunking happened and then a loud clicking noise, like a caoster between the spokes on a bicycle. Based on my reading and research it sounds like I might have and issue with my auto hubs. I checked the tranny fluid and had to add 1 1/2 quarts, but it shifts fine and doesn't slip. and for it to happen only when I am coming to a stop baffles me.

    Any help would be much appreciated!
  2. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    It may be the front hubs locking. Luckily, that doesn't have anything to do with the transmission case or transmission like you were fearing. I'm not 100% on the method GM uses to lock their front hubs, but it should be purely mechanical within the hub. Your cheapest and probably best fix would be to get a set of manual locking hubs and never worry about it again. Auto hubs can't be relied upon to work when you need them.
  3. tinman

    tinman New Member

    Thanks Crawdaddy for the reply. It is the hub. I put it in 4WD and it doesn't make the cunking sound or clicking noise. When I dis-engaged it I backed up and throttled it a bit and felt it unlock. Shifted it back into 2WD and it is fixed. I'll be servicing and inspecting the hubs this weekend. If necessary I will replace them with Warn Premium manual hubs.

    Happy New Year!


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