"stress risers"

Boy do we know the terms.

You actually think that someone who had the car before you de-rusted the spindle? Seriously? Even cars that sit in scrapyards have the hubs on, most of the time. How do the knuckles get rusty? And if you are in a scrapyard that has a rusty knuckle lying there, wouldn't you pass it by and get a different one? So this derusting talk is all nonsense to me.

Does it have original ball joints? Did the previous owner do all his own mechanic work? Because no shop worker is going to do anything more than clean with a rag and maybe some solvent before adding new grease and bearings and reassembling. Even in the 0.1% of the time that it's rusty. It just wouldn't happen. They're all trying to beat the flat rate, not that there's anything wrong with that.

Then add to that the fact that I've taken apart hubs and seen that exact surface texture, many times. Under the grease. My conclusion is that hundreds of millions of cars left Detroit with that same surface texture in that area.

Now on to how the member is stressed. The spindle is a cantilever beam and the maximum moment is at the root of the spindle, tapering off to zero at the point where the outer wheel bearing exerts a force on the spindle. If the vehicle is rolling straight the upper side of the member is in compression, which does not affect the "stress risers". It's only where the tire is trying to tuck under the car that there is a possibility of this area being in tension, and that tension is opposed by the weight of the car. So the amount of tensile stress in that area may be quite a bit less than imagined.

So what happens IF all the planets line up and the spindle fails? It bends. Yes, that would probably lock up the wheel, but in such an extreme case there would be warnings as the spindle bends through its elastic region before going into the plastic (yielding) region.

So I'd certainly use that spindle and not give it another thought. On my daughter's car.

R.