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Step 3Inspect the bearing surfaces
With rag #2 soaked in more fresh solvent, repeat the procedure outlined in the previous step for the ball bearings themselves and set them aside.
DO NOT USE A MAGNET TO HOLD ANY PART OF A BALL-BEARING ASSEMBLY TOGETHER FOR ANY REASON! Doing so will magnetize the parts and actually draw damaging metallic particles into the bearing and cause a premature failure later on in it's life.
Use the same rag to clean the inside of the hub and especially the bearing cups and cones as thoroughly as possible. Now it's time for inspection.
An ideal is that you should see a relatively even wear line on the cones that looks like a polished line that is centered in the curvature of the cone taper. This should be matched with the same impression on the inside of the bearing cup (race) in the hub.
Inspect each ball itself for defects such as pitting or galling. Remember these parts are "case-hardened", meaning they are harder on the very outside than on the inside. Visualize a steel M&M...This goes for the cone and race as well. Pitting will appear like the metal was "pinholed", and is usually the result of abrasive contamination. Galling looks more like some kind of acid burn, and is a result of contamination and/or lack of lubrication, where the metal has eaten itself. Only extremely minor pitting is something you can get away with on occasion. Galling will result in you never being able to properly adjust bearing preload and will just roughen every other contact surface like a contagious disease; dispose of any part demonstrating a galling effect. If the cup (race) in the hub is galled, junk the entire hub assembly regardless of the apparent condition of the individual parts. The only salvageable part of such a condition is the axle stud itself if anything, if it is not sprung.
Pay attention to the wear line around the circumference. If the line gets wide, you can see the load-bearing area, but if it gets too wide, it shows a bearing well-lubed, but poorly adjusted or not maintained, for too long a period. A wear line should not deviate more than 5% in width from thinnest to thickest. If it does, junk the part as it has worn way too far out of round to be useable. You didn't get to it in time to save it....
I cannot get accurate photos of the difference. so an illustration will have to do. The first is an acceptable wear line, the second is a good reason for recycling and demonstrates a potentially bad bearing group that has soured the entire hub operation. If your bearing cone looks like this, odds are that you are in the market for a new hub. The example is of a cone from opposite the galled bearing on the other side. This is how the effect ruins the other bearing, and why I say to toss the whole assembly when cups go bad. Only in certain special circumstances can a cup be saved from the hub with any hope of positive results.
The illustration provided shows an ideal condition. You can never repack your hub bearings too often.
DO NOT USE A MAGNET TO HOLD ANY PART OF A BALL-BEARING ASSEMBLY TOGETHER FOR ANY REASON! Doing so will magnetize the parts and actually draw damaging metallic particles into the bearing and cause a premature failure later on in it's life.
Use the same rag to clean the inside of the hub and especially the bearing cups and cones as thoroughly as possible. Now it's time for inspection.
An ideal is that you should see a relatively even wear line on the cones that looks like a polished line that is centered in the curvature of the cone taper. This should be matched with the same impression on the inside of the bearing cup (race) in the hub.
Inspect each ball itself for defects such as pitting or galling. Remember these parts are "case-hardened", meaning they are harder on the very outside than on the inside. Visualize a steel M&M...This goes for the cone and race as well. Pitting will appear like the metal was "pinholed", and is usually the result of abrasive contamination. Galling looks more like some kind of acid burn, and is a result of contamination and/or lack of lubrication, where the metal has eaten itself. Only extremely minor pitting is something you can get away with on occasion. Galling will result in you never being able to properly adjust bearing preload and will just roughen every other contact surface like a contagious disease; dispose of any part demonstrating a galling effect. If the cup (race) in the hub is galled, junk the entire hub assembly regardless of the apparent condition of the individual parts. The only salvageable part of such a condition is the axle stud itself if anything, if it is not sprung.
Pay attention to the wear line around the circumference. If the line gets wide, you can see the load-bearing area, but if it gets too wide, it shows a bearing well-lubed, but poorly adjusted or not maintained, for too long a period. A wear line should not deviate more than 5% in width from thinnest to thickest. If it does, junk the part as it has worn way too far out of round to be useable. You didn't get to it in time to save it....
I cannot get accurate photos of the difference. so an illustration will have to do. The first is an acceptable wear line, the second is a good reason for recycling and demonstrates a potentially bad bearing group that has soured the entire hub operation. If your bearing cone looks like this, odds are that you are in the market for a new hub. The example is of a cone from opposite the galled bearing on the other side. This is how the effect ruins the other bearing, and why I say to toss the whole assembly when cups go bad. Only in certain special circumstances can a cup be saved from the hub with any hope of positive results.
The illustration provided shows an ideal condition. You can never repack your hub bearings too often.
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