Is there a secret to getting the six bolts from the CV halfshaft to the output flange to stay tight?

There is not much thread in the flange by design, but what is there is covered in grease as it goes through the bearing carrier. I sprayed the bolts and the holes in the output shaft down with brake cleaner and wiped them down. But a week later, they had all backed out.

When a CV comes off the flange on a Gen 1 X5, it will not move at all.

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2001 E53 3.0 5pd