Quote:
Originally Posted by macdonge
On a related note (not being a machinist), how do you go about mounting the housing in a lathe to perform this job?
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Well, there are two or three ways. I first started doing them by machining a large center that I indexed off of the Differential Bearing Race in the housing and jury-rigged a dog to rotate it. I have also used the jaws of a 3-jaw chuck to grab the inside of the bearing race counterbore. Finally, about 10 years ago I made a fixture that I clamp into a 4-jaw chuck on my big lathe (Howa 17x59) that I machined a relief to mimick the Differential (Banjo) Housing. After I have indicated in the fixture, then it is basically plug & play on that end. That puts the Hub Bearing Race end of the axle housing towards the tailstock. I use a bullnose live center on that end. I typically indicate that end from the step in the housing that pilots the Brake Housing (Backing) Plate. If I need to adjust it to centerline, I generally use aluminum foil folded to act as a shim on the low side. If I am still struggling getting it to zero, I will adjust the tailstock to center it.
The one thing I do is straighten the housing prior to doing any machine work. Most housings we see are bent some. We use a torch with the housing between centers to shrink it back into alignment. Next, I machine the flange end to true it where there will be a good gasket surface to seal. Then the race end is machined.
One final trick that I do (-if I am re-using original axles is I machine the area that the Brake Housing Plate attaches to by about 0.015". By machining this, it allows the plate to position further inboard which generally keeps the Brake Drum from rubbing the plate. I do this because I hate using axle shims with a passion, and this eliminates the need for shims in the event of a worn hub.
As far a race interference, I think that really depends more on your installation method. I try to hit between 1½-2 thousandths, and depending on my final size, I have been known to stick housing into the shop 'fridge overnight and warm the race sleeves to enlarge them. Generally they fall right on. On the other hand, most bearing retainer compounds I have used release when heated, so I not sure how well these fluids will work when they have been heated during the race installation. Over the years I have had a few times where I missed my measurement and found myself machining to 0.0005", -or even less than that. In those instances, I typically will do a light knurl and make a small clean-up pass to true the surface. At that point, I am still less than 0.001" interference fit, and that is when I use Loctite Bearing Retainer and use a hydraulic press to push it on. Those work (-and last) just as well as those with two thou. of interference.
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