Malleus
Far west of Siegen
No, there is no such thing as bearing mount sealant. The journal on the shaft and bore in the housing have to be the correct size to support the bearing load. In the case of some bearing installations, the full floating rear axle bearings, for example, the press is in the housing and the bearing slips on the shaft. This is done for purely practical reasons; you can't get a puller on the bearing when it's in the housing, mounted on the shaft.
In the case of a motor, or alternator/generator, with a soft metal housing, the fit should be fairly close, size for size (meaning the bore and journal, or outer race and bore, should be the same size) or a very light press (0.0001-inch). Usually, the bearing is pressed into the housing, again for practical reasons, not engineering requirements. If your bearings slips onto the shaft, but without any observable wobble (of the inner race), it's probably OK. If it falls into the housing, you have a problem. Since the housing is aluminum and the bearing is hardened steel, it'll spin and the fit will continue to open as it does. Eventually, the bearing will fail, because it's not spinning true to the intended rotor axis. And then you really have a housing in need of a sleeve, or replacement.
Bearing fits for even simple Conrad-type bearings, like those used in motors, are critical for bearing life. The air gap in an electric motor between the rotor and stator has been designed to be constant, to prevent field fluctuation, and to prevent collision when operating (remember it's not sealed, so crap can get in there), so the bearing has to do its job well.
As I mentioned above, especially since this is an aluminum housing, the "correct" solution is to open the housing bore, sleeve it (say with a bronze sleeve) and then press the bearing in the sleeve. You'll nee a lathe to do this, (well, it could be done on a mill with a flycutter, but that would be harder, and some genius with a lot of money could do it on a 5-axis CNC, but anyway...). This is what I would do, if my 40 need a new alternator and I couldn't get the correct parts, but I'm a rabbit-hole guy. Most everyone would tell you to get a new Rock Auto alternator and move on with life.
Alternately, you could try Loctite 262, which is designed for threads, but it doesn't know the difference when it's put on, and as long as the heat doesn't get above the operating temperature of the Loctite, it'll probably be OK. That way, when the bearing does need to be replaced, you can apply a little heat and the Loctite will soften enough to allow you to get the bearing out. It'll be toast at that point anyway, so the heat won't bother it.
In the case of a motor, or alternator/generator, with a soft metal housing, the fit should be fairly close, size for size (meaning the bore and journal, or outer race and bore, should be the same size) or a very light press (0.0001-inch). Usually, the bearing is pressed into the housing, again for practical reasons, not engineering requirements. If your bearings slips onto the shaft, but without any observable wobble (of the inner race), it's probably OK. If it falls into the housing, you have a problem. Since the housing is aluminum and the bearing is hardened steel, it'll spin and the fit will continue to open as it does. Eventually, the bearing will fail, because it's not spinning true to the intended rotor axis. And then you really have a housing in need of a sleeve, or replacement.
Bearing fits for even simple Conrad-type bearings, like those used in motors, are critical for bearing life. The air gap in an electric motor between the rotor and stator has been designed to be constant, to prevent field fluctuation, and to prevent collision when operating (remember it's not sealed, so crap can get in there), so the bearing has to do its job well.
As I mentioned above, especially since this is an aluminum housing, the "correct" solution is to open the housing bore, sleeve it (say with a bronze sleeve) and then press the bearing in the sleeve. You'll nee a lathe to do this, (well, it could be done on a mill with a flycutter, but that would be harder, and some genius with a lot of money could do it on a 5-axis CNC, but anyway...). This is what I would do, if my 40 need a new alternator and I couldn't get the correct parts, but I'm a rabbit-hole guy. Most everyone would tell you to get a new Rock Auto alternator and move on with life.
Alternately, you could try Loctite 262, which is designed for threads, but it doesn't know the difference when it's put on, and as long as the heat doesn't get above the operating temperature of the Loctite, it'll probably be OK. That way, when the bearing does need to be replaced, you can apply a little heat and the Loctite will soften enough to allow you to get the bearing out. It'll be toast at that point anyway, so the heat won't bother it.
