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Some of you know I worked on a Cobalt recently, one repair I ended up doing that may help someone down the road was an Axle repair. I did report that I had to fix the axle nut threads, they were stripped, a new axle was not available so I threaded the axle down from a 13/16 nut to a 3/4 nut size, both used a 20 threads per inch thread. This part worked out just fine but assembled I found out why the previous nut was stripped. At some point in time this trailer had a bearing go bad. Not sure about the specifics as I saw it long after the previous incident and I don't have the history but the actual outer bearing was beat in some areas. Assembled the bearing was loose on the shaft. The shaft looked fine, not burned or blued by high heat. Not sure how it got this way but the problem was trying to adjust the wheel end. As you tightened the axle nut the wheel started to adjust, but never actually got the play out of the wheel end. This trailer uses the standard automotive A-4 bearing or industry SAE # L44649 bearing, L44610 Race. The L44649 bearing has an ID of 1.0625 and this was too large on the beat up axle. A new axle was 6-8 weeks away so we looked at options. I found bearing part # A14 is identical and uses the same bearing race L44610, the only difference is the actual bearing part # L44643 is 1.000 in ID. This gives us .0625 plus .003 to allow the bearing to install properly. So for $15 a L44643 was purchased. About 2 hours of filing, and a lot of sanding with 18" of emery cloth while using a micrometer set at 1.010. I was amazed, first that this seemed to be working and second that it did not seem hard at all to maintain roundness using the emery cloth. I would file the high spots a little. The mic would show high and low spots. I would hit it with the emory cloth and the high and lows would smooth right out. The emory cloth would encircle about 75% of the bearing and I worked it with a sawing motion using smooth action while rotating around best I could to maintain roundness. Once I found I could get the shaft to 1.010 and it measured to be round I went ahead and took it down to 1.000 which was still way to tight to install the bearing. Took it down to .0997 and that A14 bearing slid right on, a nice tight fit and I am confident this axle will not ever cause an issue. I wrote the part numbers down inside the brake drum for the next wrench. The wheel end adjusted perfectly with the new bearing installed and worked perfect on the 500 mile trip this boat took later. Every time I pulled over on the trip I walked around and checked bearing temps. they ran cool the whole trip. I share this because it may help someone save an axle just like we did. I will say if you see blue burned into the axle stub it is junk, the metal will be brittle and dangerous, this axle was beat up but did not show signs of heat so I tried the fix. It was tedious for sure but the axle was saved. I considered welding up the surface and getting it back to stock factory size but my welding skills are not up to that task and the heat with my limited welding skill would have ruined the axle. Bearing size listings are available, you can look them up by axle shaft size or by bore size, it also lists the bearing width. We were lucky to find a bearing that uses the exact same outer race but had the smaller inner shaft size while having the exact same width. I am sure some will say this is back yard hack work, and it is, but my mic is accurate, this was a ball mic, I could slide it in and out, around the entire bearing surface, it measures perfectly. I did use the dial indicator at first but it was not as accurate or easy to use as the ball mic. Maybe this will help another wrench fix a bad axle shaft.
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