Hi people,my 87 tdt just got some work done,i put new spheres in the back to help out give me a smoother ride,then i bled the system and i see no leaks,but my rear will sag for a week after i put a heavy load,i cant tell it it reloads by uitself or a long road trip will spring it,i was wandering if anyone knew what could be causing this,before i changed the spheres i had a bumpy ride but it would never sag after loading it up,but now when i go to costco and buy a lot of heavy stuff such as water cases etc it will sag for days.