In general, the actual preload on the balls is always very light. Where a huge number might come from is the tightening torque on a nut which is clamping inner race + spacer + inner race into a stack. This brings the races into position where they apply a light pressure to the balls. No matter how much more you tighten such a locknut, the preload on the balls will not change because the spacers are what create the preload, which is basically ground into the bearing at the factory.
In a back to back or face to face paired bearing assembly, no spacers are used, of course, and the factory preload occurs when the races meet. But if the bearings must be seperated by the spindle design, then typically, both spacers would be exactly the same length, between the inner and outer races. It is possible to monkey around with the preload under these circumstances, by altering the length of one spacer relative to the other one.
So, you may not know exactly what you have. When I rebuilt my Haas spindle, I made up the bearing and spacer stack and applied pressure to the stack with a plate on top, via use of a hydraulic press, and moderate pressure. From this, I could get a feel for the length of the outermost spacer relative to the inner one (which is not accessible in the stack). Now I went totally on a hunch and a bit of experience , but I lapped only one end of the outer spacer length carefully (with a lot of careful checking of the length to make sure I was keeping the ends parallel) until it took firm finger pressure to slide the outer spacer back and forth in the stack. That, I concluded, was the preload I wanted. It worked out well, too.
Haas retains their bearings with shrink fit spacers, not nuts. So the actual preload on the stack is unknown. All I did was heat the spacer, drop it on the spindle and let it cool. Then, because it would be a little bit loose lengthwise after cooling off, I bumped it on tight against the stack with the press. One little pop sound occurred when I did this, indicating to me that the spacer had moved just a wee bit as it settled into final position.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)