Procedure for torqueing Mondial QV front hub nut | FerrariChat
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Procedure for torqueing Mondial QV front hub nut

Discussion in 'Mondial' started by 85QVEuro, Nov 2, 2023.

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  1. 85QVEuro

    85QVEuro Formula Junior

    Jan 15, 2021
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    Joe
    #1 85QVEuro, Nov 2, 2023
    Have read 325 ft. lbs for the large nut on the front hubs which seems excessive as I seem to get binding when I tighten past "zero lash"

    Would appreciate if someone can explain the proper procedure and whether 325 ft. lbs is accurate. It seems like an intuitive job until you hear that its supposed to be 325 ft. lbs. (if true)

    Thanks - Have pics if needed
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Nov 2, 2023
    Last edited: Nov 2, 2023
    Where? That's way too high (that's more like the torque spec for the single-lug TR center wheel bolt), but you shouldn't get any binding either -- if properly assembled, the torque on the large M20 nut has nothing to do with the bearing preload. The 5-lug TR uses the same M20 x 1.5P nut (124642) and is 118 ft-lb.
     
  3. 85QVEuro

    85QVEuro Formula Junior

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    #3 85QVEuro, Nov 3, 2023
  4. 85QVEuro

    85QVEuro Formula Junior

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    #4 85QVEuro, Nov 3, 2023
    From WSM...(and the six bolts that hold the bearing to the steering knuckle are torqued to 30 ft. lbs not 33 as stated in last post)
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  5. 85QVEuro

    85QVEuro Formula Junior

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    #5 85QVEuro, Nov 3, 2023
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #6 Steve Magnusson, Nov 3, 2023
    Last edited: Nov 3, 2023
    It's built into the bearing parts themselves. There is a small gap between the inner races when the load from the nut is just above zero (i.e. all the slop removed). As the M20 nut is initially tightened from there, this closes the gap (until the two inner races make contact) and "squeezes" the balls a very small amount (to provide the preload), but additional torque on the M20 nut does not increase the bearing preload more.

    Did you replace the bearing(s) or just clean/repack your existing bearings?

    Unfortunately, this later design with the M20 nut isn't shown in either the Mondial8/QV WSM nor the TR WSM (both designs were changed after their WSM was written). One thing you might do/try is remove the assembly from the upright knuckle and make a sub-assembly like this:

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    with the M20 nut tightened = that should spin freely/ smoothly. If it doesn't = something wacky in the bearing or maybe the inner race(s) are hanging up on the shaft somehow. If it does spin well = the trouble must be related to the bearing outer race not fitting in the upright knuckle properly. Just a thought...
     
  7. 85QVEuro

    85QVEuro Formula Junior

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    #7 85QVEuro, Nov 3, 2023
    Thanks Steve - the hub was disassembled and bearings and races inspected - both looked good so they were cleaned, re-packed and assembled as in the photo below, which is similar to the assembly in your picture above. At that point, I didn't tighten the large nut because I thought it should be done when the front suspension was re-assembled to adjust the pre-load (as you would with other cars). It is installed and fits in the upright knuckle fine and spins freely but think it would bind if I torqued the big nut a lot...

    There are two holes on the side of where the large nut goes (which can be seen in the second picture) and if I over tighten it to the point of binding, I can loosen the nut slightly and put a punch in those two holes and tap to regain clearance - not sure what's up with that. Maybe I should tighten the M20 nut to whatever the specified torque is then put the punch in the two holes to see if I can then re-gain clearance as the bearing will have seated more?? What torque did you use on that nut when you did yours? As always, appreciate your help.

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  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Nov 3, 2023
    Don't like that as the "tapping" is moving the outermost inner race away from the vertical surface on the hub that it should be seated against. Indicates to me that the innermost inner race is hanging up on the OD of the hub. When you tighten the M20 nut, the "head" on the shaft should be pulling both inner races together along the OD of the hub and up against the vertical surface of the hub (where those holes are).

    I used the 118 ft-lbs as (very confusingly ;)) specified in the TR WSM.
     
  9. 85QVEuro

    85QVEuro Formula Junior

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    #9 85QVEuro, Nov 3, 2023
    Steve - Thanks again. I will go through it this weekend and try to sort it out - Joe
     
  10. 85QVEuro

    85QVEuro Formula Junior

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    #10 85QVEuro, Nov 6, 2023
    Thanks Steve - put the new nuts on and torqued to 118 ft. lbs
     
  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,571
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #11 Steve Magnusson, Nov 6, 2023
    And all seem OK now?
     
  12. 85QVEuro

    85QVEuro Formula Junior

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    #12 85QVEuro, Nov 6, 2023
    Steve - Yes, I don't know what I was doing or thinking before but it's torqued to 118 ft. lbs and as you stated, tightening the nut did not cause binding - spins nicely. Thank you again, always appreciate your input/knowledge/advice - Joe
     

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