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Thread: Timken rear axle bearing cup issue

  1. #1
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    Timken rear axle bearing cup issue

    I just got the outer axle bearing cones pressed onto the rear axles for the Timken assembly and I've noticed something that could be a problem. When I put the outer bearing cup into the axle housing on the driver's side it is a snug fit and will need to be tapped in, which is what I expected, but on the passengers side the bearing cup slides right into the housing without any resistance.
    Is this correct and normal? If not is there some kind of sleeve I can add to the axle housing to tighten up the fit for the bearing cup? Would appreciate any help or advice.

  2. #2
    Use this link. I don't use the Loctite, but it's good insurance if you don't want to remove the race in the future.
    http://www.grainews.ca/2014/12/10/ho...-bearing-race/

  3. #3
    Super Moderator bmorgil's Avatar
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    Some bearing cup rotation is allowed. The Cups need to be able to move in and out for adjustment. Clean the axle bores and the cups should be a very nice slide in fit. As you shim the axles in and out for proper end play, it will be easier to do if the cups don't get stuck in the axle tube bores.

    In the design of heavy truck transmissions it is common practice to allow bearings to "creep in the bore". If a bearing is functioning properly it roll's on the bearings and there is little tendency to rotate the cup. The creeping cup promotes even wear on the bearing. The lack of pressure from a press fit on the cup helps to keep the bearing race round. This all depends on application of course. Sometimes it is a press fit, sometimes it is not. In the case of the axle wheel bearings, this is the basic idea, along with installation and setting the end play.

  4. #4
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    bmorgil, thank you for the great explanation. I'm new to all of this and your explanation really helps my over-all understanding. I had already surmised that I needed to shim for limited end-play and that once I torqued down the axle nut to 150lbs everything was going to be set. It's really a relief to know that I may not be screwing something up. Thanks again.

  5. #5
    Super Moderator bmorgil's Avatar
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    No problem!

  6. #6
    To me a bearing cup that slides in and out with no resistance sounds like trouble. Time will tell. For more info Google bearing creep.
    Good luck

  7. #7
    Super Moderator bmorgil's Avatar
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    Quote Originally Posted by pdudleystl View Post
    To me a bearing cup that slides in and out with no resistance sounds like trouble. Time will tell. For more info Google bearing creep.
    Good luck
    Again it all depends on application. In the case of some of the rear axle bearings on the Timken and the Dana used in the Williys, they are shimmed in and out for proper end play. It is essential that they are able to move in and out with the adjustment shims. After time they may get stuck in there, and that's OK. In general however they are not a press fit. The load on the bearing is such that the race is being pressed against the tube. This causes a great deal of friction since it is steel on steel. The rollers provide a much easier path of resistance. On many transmissions the race's on tapered roller bearings are a slip fit. The inner usually presses on the shaft and the outer is a slip fit. The Dana transfer case is another example. In order to adjust the output bearing, it uses a shim pack and the outer race is a slip fit in the case and cap.

    As always be careful with internet information. Bearing fit and application is a science in itself. At Dana we always involved the bearing manufacturers even though we had some excellent bearing engineers of our own.
    Last edited by bmorgil; 11-10-2019 at 07:20 AM.

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