Front Wheel Bearings
08-25-2016, 05:40 AM
#16
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Year: 1999
Model: Cherokee
Engine: 4.0
You get what you pay for with bearings - Timken, SKF, and Moog are of good quality. I'm a Timken man, myself.
Many people, however, overlook just how critical proper preload is to bearing life. In an XJ hub setup, preload is developed by the hub nut on the axle stub shaft. So...make sure the threads on your shaft and nut are very nice and clean. Then absolutely 100% make sure you torque them to spec. Not less, not more. I believe the spec calls for plain dry threads. So don't lube them or apply loctite. If you do, you'll have to back off on the torque spec to achieve the same/correct bearing preload.
Many people, however, overlook just how critical proper preload is to bearing life. In an XJ hub setup, preload is developed by the hub nut on the axle stub shaft. So...make sure the threads on your shaft and nut are very nice and clean. Then absolutely 100% make sure you torque them to spec. Not less, not more. I believe the spec calls for plain dry threads. So don't lube them or apply loctite. If you do, you'll have to back off on the torque spec to achieve the same/correct bearing preload.
^^ X2
08-25-2016, 09:51 AM
#17
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Year: 1998
Model: Cherokee
Engine: 4.0L
OMG someone understands what happens when you have lubricant on threads! My faith is restored. I love the gallon of antiseize on wheel studs. That's my favorite. "why do my lugs come loose?" uhh yeah here's your problem! Quick way to stretch the threads!
08-29-2016, 04:18 PM
#18
Seasoned Member
Where T is torque, K is a dimensionless torque coefficient related to friction between the threads, D is nominal bolt diameter, and P is bolt preload/tension/clamping force.
This is a very rough engineering approximation. K is usually experimentally found or assumed based on previous studies or applications.
If P and D stay the same and the threads are lubed to reduce K, T also goes down.
Trying to determine a new K value at home for your stub shafts is naive. Keep your threads dry folks.
And now you have completed bolted joint design 101.
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