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#16
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IMHO I think many bering failures are due to loads being placed where they shouldn't be when pressing the bearings into position. The rollers are very small and will not tolerate any abuse. I just can't see any other reason being a real stand-out problem, other than the roller dimensions.
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ASE Certified Master Automotive Technician w/L1. ASE Certified Master Medium/Heavy Truck Technician. Certified EVT (Emergency Vehicle Technician) |
#17
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Well I think these bearings fail becasue of too much preload. I got some used bearing/hub assemblies from a yard and I was surprised at how hard it was to rotate the axle hub. It was very smooth but oh man it took some force to turn it. That is what happens when the pre-load is too high.
I think that putting the assembly together with a press is the wrong thing to do. There is no way NOT to over pre-load the bearing when a press is used. I think the hub tamer approach with a power screw is the way to do it. This problem with the bearings is definantly assembly related because some of us have gone well over 100k miles with these bearings.
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#18
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Quote:
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1992 LS Touring (6/91) - Currently undergoing a five speed swap Black over Claret with spoiler; 235,000 miles; Mods: 2002 Legacy 5 speed, ACT Pressure Plate, Excedy Clutch, Short Throw Shifter, Aussie Powerchip 1992 LS Touring (6/91) Black over Claret with 2.5" setback spoiler; 202,000 miles; Mods: B&M Cooler 1994 LSi (4/93) Bordeaux Pearl; 198,000 miles; Mods: Weight reduction. 1969 Mustang GT Convertible 1970 Mustang Convertible 2000 Ford Excursion Sola lingua bona est lingua mortua. My Locker |
#19
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My use of the term 'press' was generic. Whether a press or hub tamer is used is irrelevant, both actually do the same thing. The problem lies in the incorrect usage of equipment and applying pressure where it doesn't belong. Purely a matter of people that don't think and/or understand what they are doing. The bearing can't be pressed into the knuckle by pushing against the inner race, nor can the hub be pressed into place by beating it through the inner races, supported by the rollers and outer races.
BTW, the design of the bearing determines the amount of pre-load, the inner races only allow so much (or little) clearance. I would imagine the manufacturer employs some sort of select fit processing. I still stand behind my belief that the bearings would be more sturdy if the rollers were more robust. The reasoning behind their diminuitive size is one of fuel economy - smaller rollers equal lower rolling resistance.
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ASE Certified Master Automotive Technician w/L1. ASE Certified Master Medium/Heavy Truck Technician. Certified EVT (Emergency Vehicle Technician) |
#20
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I keep hearing the same story from my dad (long time mechanic) and the former Subaru dealership - People keep overtightening it. Too much preload.
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#21
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Bearing preload?
If the outer track is not pressed into the housing fully, or there is a burr or a bit of grit behind it, when the axle nut is torqued up, the inner race next to the nut will be loaded up, to try to push the outer track into place. This will preload that track too much, and if the outer track does move into place, the preload will be lost.
I agree that the race does seem to be under sized for the lateral thrust that this car can generate, but it does seem strange that some factory fitted bearings go out in 60kl, and some last forever. Harvey.
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