Can anyone explain the mechanical difference between front wheel bearings with a standard oil seal (that need repacking) vs. the newer "sealed" or "lifetime" units? Is it just a seal with a tighter clearance? I don't see how anything constantly rotating and/or turning can completely shut out the elements. Even if nothing gets in or out, don't they need a special grease that doesn't degrade for 200k+ miles?
U.S.
Who's lifetime are they talking?
I have gone through all the sealed bearings in my Jeeps and have gone through 12 sealed "lifetime" "heavy duty" u-joints in 5 years due to water contamination.
The term is just sales BS for 'planned' obsolescence.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
What were the symptoms of bearing failure, and what year vehicle(s) are you talking about? I rarely drive in axle-deep water. Bearing replacement on my truck (1997 Toyota 4x4) is apparently not a DIYS job; it requires a multi-ton press. After 180k miles I hear and feel no problems and I'm not sure how I'd detect anything subtle.
U.S.
I typically run my cars for 300k miles and the ONLY bearing failure was one that was defective when installed on a new car. My experience seems to be the norm among friends and co-workers. Bearing failures were not unusual with the old standard seal units, but I suspect that was the result of drivers not keeping up with maintenance.
Can't tell you about the expected life of bearings when used in extreme circumstances, since I don't drive my cars like that. I think common sense would indicate that bearings along with most other components would have their useful life shortened considerably if given a steady diet of off-road banging around rocks and stumps and submersion in mud and water.
Mike Roma> Who's lifetime are they talking?
My Land Cruiser 100 series had one rear wheel bearing failure at 85000 miles. Like you I never travel through deep water. I'd like to think it was a one-off but time will tell. Symptom was a squeak when going round bends in one direction when the vehicle was hot [done more than 50 miles in a trip]. Found the outer bearing race had worn through the case-hardening. Not a catastrophic failure but it could have been at some point if left too long. Never had such a failure in a Land Rover/Range Rover. Plenty of other problems mind you.
Huw
They have some pretty good seals on bearings these days, but I figure they are talking about the lifetime of the bearing, not you, the car, or the current government...:) Just means no routine service is required, but still check to make sure the bearing is still there...
Unfortunately, it often means that the "routine service" requires things like a press or spring compressor, rather than a crescent wrench and a pair of needle-nose pliers like it takes to re-pack the bearings on an older car.
No, it means the routine maintenance is spin the hub (or other obvious check) to see if the bearing is bad. The point of these things is that they are sealed in a near-perfect environment, adjusted perfectly, with the perfect amount of the perfect lubricant. Bearing engineers love these things because end users have a really hard time screwing them up because they aren't going at them with various no-name greases, and adjusting them too loose or too tight. No need to disassemble anything unless you are charging for the service and need to make a buck or two. the only maintenance is replace the bearing, and no one just replaces stuff that is still fine and dandy.
I've had sealed for life bearings in the rear hubs of race cars that were made in 1962. They're not new technology. You check them, and only replace them either when they have passed a design life or when they are going bad.
Brian
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