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new hub and rotor 1989 GMC Suburban

Discussion in 'Suspension, Steering & Brakes' started by DuRolf, Nov 23, 2020.

  1. DuRolf

    DuRolf Junior Member

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    First Name:
    Rolf
    Truck Year:
    1989
    Truck Model:
    V1500
    Engine Size:
    350 TBI
    Hello folks
    I just bought a 1989 GMC Suburban V1500 350TBI 700R4, and it came with a crunchy grind from the front end.
    I took the front wheels off, and found the inner side of of the right front rotor to be heavily scored. I took the caliper and pads off, and found the brake pad on the caliper piston side to be down to the metal.
    Interestingly, the other three rotor surfaces, outer on the right and both on the left, were in great shape without even a lip and with the bevel seemingly as new.
    The seller had replaced the rotors with slotted aftermarket models, though the calipers were still factory.
    I think the right caliper was not retracting properly, and ground down the pad and rotor surface.
    What followed was a frustrating journey of many days with a major auto parts chain, who first sold me the front rotor hub for a RWD Suburban and then sold me a damaged hub rotor assembly! I now know to inspect parts in detail before leaving the store.
    But now all is good. I put new bearings in the new hub rotor, (which came with the races installed) and a new inner seal.
    The Haynes manual had funny instructions for tightening the spindle nut on a hub with a manually locking system.
    - Torque to 50 ft lbs, back off 90 degrees, tighten to 35 ft lbs, back of 3/8 of a turn.
    This resulted in a spindle nut that was not even finger tight. Why would they mix units of rotation? What does 3/8 of a turn mean? I interpreted it as 135 degrees. Does it have a different meaning in Haynes - speak?
    I ended up putting the wheel back on, and tightening the spindle nut arm strength (not body weight) tight with a two foot handle half inch drive. Then I grabbed the tire at noon and six o clock and tried to wiggle it. It was tight. I then spun it with one hand starting at noon, and the tire spun about 3/4 of a revolution. I then put my hand on the side and gave it a bigger spin, and it spun about 1 1/4 revolutions. I decided this was appropriately snug.
    I then put on the spindle washer and lock nut and Warn locking hub assembly with its spring clip that fits against the inner lip at the outside of the hub.
    The drivers side rotor is in such good shape that I left it as is, even though it means I have a slotted rotor on that side and a factory style rotor on the passenger side.
    New brake pads all around now give a smooth strong stop. The vehicle doesn't pull to one side.

    Inner brake pad right side.png

    Inside right front rotor.jpg

    Bleeding new caliper and line.jpg
     
  2. TubeTruck

    TubeTruck I like anything fast enough to do something stupid

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    Tightening the first nut to 50lbs seats the bearing in the race, then back it off 3/8 of a turn, figure a pizza is 8 slices, back it off no more than 3 slices. I back it off 90 degrees to be safe. Then tighten again to 35ft lbs This should put the pin in the correct location for the washer and not too much pressure on the bearings to cause premature wear. The outside locknut I've heard a few different settings, 50, 80, 150ft lbs. I tightened mine to 100ft lbs.
     
  3. DuRolf

    DuRolf Junior Member

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    Truck Year:
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    Truck Model:
    V1500
    Engine Size:
    350 TBI
    Thanks for the ideas. My two spindle nuts and the spindle washer don't have pins that stick out in the axis of the axle. The washer is keyed, and sticks into a slot on the spindle so it can't spin.
     
  4. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    @DuRolf

    "I ended up putting the wheel back on, and tightening the spindle nut arm strength (not body weight) tight with a two foot handle half inch drive. Then I grabbed the tire at noon and six o clock and tried to wiggle it. It was tight. I then spun it with one hand starting at noon, and the tire spun about 3/4 of a revolution. I then put my hand on the side and gave it a bigger spin, and it spun about 1 1/4 revolutions. I decided this was appropriately snug.
    I then put on the spindle washer and lock nut ....."


    If this is how you installed the hub, your bearings are too tight.

    Some facts and theory:

    Ball bearings should be pre-loaded.
    Roller bearings should have zero lash.

    Roller bearings still work fine if there is a small amount of lash. If they are pre-loaded, they will fail.

    Now so you can understand why and how, the inner nut should be slightly loose, (some lash) when installed. The outer nut when tightened will push the inner nut across the threads an make the inner nut tighter.

    When the hub heats up, everything expands, making the fit even tighter. Also, no room for the grease to keep the bearing lubed.
     
  5. Itali83

    Itali83 Full Access Member

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    Yup, rule of thumb is grease bearings need to be a bit loose to not push all grease out of the way and get hot. Oil bearings can be a bit tighter but still not too tight. Yours are too tight.

    ben
     
  6. DuRolf

    DuRolf Junior Member

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    Thank you. I will loosen them. Maybe, torque to 50 ft lbs, back off 90 degrees, torque to 35 ft lbs?
     
  7. Bextreme04

    Bextreme04 Full Access Member

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    No, they should not be torqued to anything for the final setting. The GM service manual for Dana 44's and 10 bolt front axles says to:
    1. Torque inner nut to 50 ft. lbs while spinning the bearing hub to seat the bearings.
    2. Back off the inner nut(90 deg or 1/4 turn) and then retorque to 35 ft-lbs while spinning the bearing hub.
    3. Back off inner nut 3/8's of a turn(this is exactly halfway between 1/4 and 1/2 turn)
    4. Install lock washer(if you have to turn the inner nut to get the lock washer on you should loosen it more, not tighten it)
    5. Install outer nut and torque to 150 ft-lbs

    The inner nut WILL be slightly loose if you do it this way. You will be able to very slightly pull the hub in and out. It actually has a spec for end-play of the hub, but I can't remember what it is. I have seen posts where people verified the correct end-play when this procedure was followed.

    If you torque to 35 ft-lbs and then leave it, you will burn your hub up pretty quick on the highway.
     
  8. idahovette

    idahovette Full Access Member

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    The inner nut SHOULD have a pin that protrudes so the key that's in the axle and the pin lock everything together so the inner nut will not turn?
     
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  9. highdesertrange

    highdesertrange Full Access Member

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    yes the inner nut MUST have a pin that washer locks into. highdesertranger
     
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  10. ssgleoleal@yaho

    [email protected] Junior Member

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    maybe replace the other side if not already done. Makes for even braking, less headaches
     
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  11. highdesertrange

    highdesertrange Full Access Member

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    Leo is correct all brake parts should be replace in pairs. what you do on one side should be done on both sides. highdesertranger
     

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