SpeedyC2

As another data point, I recently replaced the castor blocks and the noise seems to be gone.

I still swear it was coming from the rear of the car, and there did not appear to be any issue the internal anchor nut weld for the castor block as rcatherton suggested, but the noise does seem to have gone away...

I'll post again if it returns!

951kaos

Rebuilt my suspension in 2009; Elephant Racing and Racer's Edge bushings; torsion bar delete; Bilstein Escort Cup coil overs; solid mounts for torsion tube; retained previous owners Weltmeister sway bars. Originally found that the machined split rings that the previous owner installed to locate the rear sway bar hit the body/frame when the sway bar loaded and made a hard knock sound; removed the split rings and used hose clamps to locate sway bar. All was quiet till more mileage was put on the car. The knock noise would appear on hot days when the suspension loaded during cornering or running over a bump on one side; but would be quiet on cold days or driving on the highway. I suspect the rear sway bar bushings on my car are now getting worn/soft as there is light mark where the bar has touched the body/frame under load. Currently planning on replacing the bushings with generic Powerflex ones and installing a plate under the mounting brackets to bring it away from the body.