Noise from the rear suspension

[NZ XR6]

A few months ago, I had the rear pads replaced. Since then, there has been an intermittent noise from the rear suspension on the right. It sounded like something was loose in the back, so I removed all of my work stuff and checked the spare wheel well, but didn't find anything loose.

it seemed most noticeable over bumps that caused a lot of suspension travel, but sometimes I would hear nothing for a week or so.

I investigated further over the Christmas break. There is a judder bar near home that seemed to provoke it at the right speed, so I drove over that a few times with the windows down. It sounded more like a creak than a clunk, if that makes sense. I jacked up the rear of the car but couldn't find any play or visible damage.

Last week I rotated the tyres and found that the rear wheel nuts had been seriously overtightened - just standing on a 1/2" power bar didn't work and I had to jump on it to loosen the nuts. So I changed the wheels over and torqued the wheel nuts to the Ford spec.

And the noise is gone - we've been away for the last week and no sign of it! I'm at a loss to know how overtightening the wheel nuts could cause the noise - any thoughts?

Needless to say, I won't be going back to that workshop again.