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Bearing Pre-load ?

Discussion in '80-Series Tech' started by rjjff88, Nov 2, 2003.

  1. rjjff88

    rjjff88

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    I started on the Birfield repack today, but I was unable to get the Pre-load under the 12.6 Lbs that the manufacturer recomends(16lbs is the lowest I could get it). Could it be that the grease was too cold? BTW I'm using Amsoil Grease. It was about 30 degrees in Washington today. If that is the case, what should I set the pre-load at?Any ideas would be appreciated
     
  2. Riley

    Riley

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    That's weird. Did you follow the procedure in the FSM where you tighten the nut and then spin the wheel for 2 or 3 times then back it off?

    If so perhaps it is the cold grease.

    Riley
     
  3. rjjff88

    rjjff88

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    Yep, Followed the directions to a Tee, Tried it a couple different times, I even tried just hand tightening the nut. Nothing worked.
     
  4. 97cruiser

    97cruiser

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    Knuckle (trunion ) or wheel bearings pre-load ? Did you play with the shims a lil ?
     
  5. Riley

    Riley

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    I assume that it's his wheel bearings.
    I'm out of ideas but I bet Doug or B would have some advice.
     
  6. AZcruiser

    AZcruiser

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    recently, 2 of us rebuilt the knuckles on a 94 and 96. The preloads were higher than FSM. Our thought was the new felt,etc on back side, every nut/bolt were torqued.
     
  7. rjjff88

    rjjff88

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    Yes, it is the Wheel Bearing
     
  8. Beowulf

    Beowulf

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    rjjff88 Darn, that's hard to pronounce... :(

    Things to check,
    * Pads dragging? Did you do this test before you put on the caliper?
    * Spring scale accurate?
    * Did you follow the steps as posted here on the list? If yes, give us the link.

    -B-
     
  9. Riley

    Riley

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    Dumb question but I assume the brake caliper is off right?

    Also since 16 lbs isn't much higher than the upper spec of 12 lbs IIRC then perhaps tighten the nut to just to the point that it just starts to increase the preload then just back it off back (effectively making sure it's not too loose).

    Check there is no play up or down or side to side. Then put it together and go for a drive (perhaps short drive to work tomorrow and then check it when warm.

    Problem is that those cone washers can take a bit of work to loosen.

    That's all the ideas I'm good for.

    Riley
     
  10. rjjff88

    rjjff88

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    Yes the brake caliper was off. I'll Try taking it for a drive tomorrow, see if that loosens it up. Thanks, Rjj
     
  11. Safado

    Safado

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    One thing I noticed when setting mine, was it matters a lot the angle at which you are pulling the scale. The only way I could get it to be consistent was to hook onto a lower lug and lean the scale against the lug just above it when pulling.

    So if you take the adjusting nut completely off, can you get a preload of less than 16? Not sure what your FSM says, but my buddies actually had a mistake in the adjusting nut torque value. (91 FSM) Make sure that yours says 48 in/lbs for the final torque of the adjusting nut instead of 48 ft/lbs like his did.
     
  12. boydmick

    boydmick RIP My Friend

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    Front preload too high!

    Finishing up my birf overhaul; guess what? My preload is just above 20 lbs with the adjusting nut removed.

    I followed the FSM to a T.

    I managed to get the preload to 16, but then there is play in the bearings.

    What else can I try?!

    Thanks,

    Boyd
     
  13. Riley

    Riley

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    How did you get the preload to 16 if when the adjusting nut is off you are getting 20 lbs?

    Dumb question but brake caliper is off, right?

    So you tighten up the nut and spin by hand then back off right?

    packed lots of grease in the roller bearings right?

    Wierd. :confused:
     
  14. Rich

    Rich

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    From Timken:

    Hardened surface nuts, tongue washers and outerjam
    nuts or lock nuts are commonly used for wheels
    with full floating rear axles and some front-wheel
    applications.

    To adjust the setting of this bearing:

    Step 1: Tighten the nut while turning the hub.
    When there is a slight bind on the bearing,
    the parts are seated correctly.

    Step 2: Back the nut off 1/6 to 1/4 of a turn or
    sufficiently to allow .001” to .007“ end play.
    Note: Failure to back off adjusting nut could cause
    bearing to run hot and be damaged. Wheel could
    lock or separate.

    Step 3: Tighten the jam nut to remove the thread
    clearance and to prevent the nut from
    backing off.
     
  15. boydmick

    boydmick RIP My Friend

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    In reverse order:

    Very wierd.

    Lots of fresh grease in new bearings/races.

    Tightened nut (43 ft/lbs) spin, spin, spin. -REPEAT-

    Backed off to barely finger tight; scale reads 22 lbs.

    Removed nut, spin, spin, spin. Scale reads 20 lbs.

    Gently pulled hub/rotor, spin, spin, spin. Scale reads 16 lbs; but bearing has play.

    Go figure!

    BTW - this is the USPS front. DS was just a little high @ 14 lbs.
     
  16. scottm

    scottm

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    I just went through the same thing. Barely finger tight on the wheel nut, then torque the locknut, still a little high on the preload. Checked it after driving a day, still the same. I suspect there's very slightly more play in the threads than new, the wheel nut moves slightly more when tightening the lock-nut against it. But what do I know :confused:
     
  17. landtank

    landtank SILVER Star

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    What type of wheel bearing grease did you use? I'm thinking possibly a synthetic?
     
  18. Riley

    Riley

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    I agree with Rick. The synth stuff is really thick and is likely causing these higher levels of drag when checking pre-load. But what do I know, I'm a newbie.

    I do know that my grease gun won't even pump my redline grease but works fine with dino. I think we should nominate Boyd to pull that side and redo the job just plain old grease and confirm that the preload is back to normal range.
     
  19. boydmick

    boydmick RIP My Friend

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    Well you're right, the grease is synthetic (Amsoil). It does seem pretty thick, but it will pump through my gun.

    O.K., I guess I'm elected. Do you know how hard it's gonna be to clean out all that brand new grease just to replace it with dino?! LOL

    I figure I will run the truck a few days and retest. Thanks for the input.

    Boyd
     
  20. Rich

    Rich

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    For years and years the standard practice for setting bearing preload in automobiles is to tigthen the nut hand tight (not using a tool), and then backing off a little bit, so the nut ends up less than hand tight. The bit about first using a wrench to get the nut tight while spinning the wheel is to ensure that the bearings are properly seated prior to the hand tightening.

    The bit about using a spring scale to measure rotational resistence is merely Toyotas attempt to get a little more precise about setting the preload. Toyota's method is dependent on "normal" grease being used and also dependent on the hub assembly being at "normal" temps, say 70 - 85 degrees. It is an unorthodox approach.

    Below is a link to a document from Timken on how to measure and use end play in order to set bearing preload. I have seen this approach specified in other factory service manuals. The advantage of this approach is that it is not dependent on the viscosity of the grease.

    http://www.timken.com/industries/automotive/autoaftermarket/techtips/VolumeIIssue3AupsFinal0104.pdf