Upper control arm bolt repeatedly backing out

[woodkd]

The right side upper control arm bolt (stock suspension) on my 69 camaro continues to back out and I have subsequently lost the washer, lock washer and bolt twice. After the first loss, I used loctite but this appears to have no effect. The bolt will back out after a couple hundred miles of driving. I suspect the issue to be related to the threads on the shaft. Any suggestions or ideas as to a cause or resolution are greatly appreciated.

Thanks in advance,

Ken