Rear suspension sagging

[S15508g]

I am completely stumped
I have an 89 Carrera i’ve been struggling with the rear suspension it keeps sagging
I’ve replaced the factory Spring plate bushings with elephants and did a whole bushing refresh with koni yellows all around
Eventually the car would sag about a quarter of an inch. To about 24 inches from ground to fender. After re-indexing torsion bars many times and inspecting everything I decided to go with the renline adjustable Spring plates with there bushings and replaced the bushing hats. I re-indexed the torsion bar higher than what it was and reinstalled everything. Adjusted the spring plates which are amazing by the way so they would read about 24 1/2 from floor to top of rear fender. After a quick sort of alignment go up and down the driveway and it’s fine after about half an hour or an hour of driving the car sinks back down to 24 inches both sides. Torsion bars are well lubricated I did not inspect them for any cracks they are labeled for the correct side. Any thoughts.

[911obgyn]

Inspect your torsion tube, any rust or cracks?

[S15508g]

How can I inspect the tube. I can look when I get the Bar out. I’ll look for cracks. I hope it’s not that. But by process of elimination it can only be bar or tube.

[dannobee]

The final step in setting ride height is a test drive to "settle" the suspension. Stiction that occurs when jacking up the vehicle won't allow the suspension to return to its "normal" position. Set the ride height, then test drive, then verify and make adjustments. The other option is if you "know" that stiction raises the car 1/2", set the ride height to compensate for that (1/2" higher than what you "think" it should be), then let it settle to your desired ride height.