[Merv and Sharon]

Dave I have 12", 250 lb QA1 rears and the DD501 12" shocks. I found that the 300lb was too bouncy and that I needed the crank up the Rebound damping a fair bit to reduce that. I also was made up some small collars from when I had 10" 300lb springs. That helped to make sure that it all stayed together on full droop. However, with the 12" springs, mine are pretty much like yours, with some degree of preload.

The rule of thumb that I was given was that the shock should be able to move within at least 60% of its travel. Mine do that. The only bump stop I can see is the small "o" ring! My old AVOs had a bump stop but far less travel than the QA1s. The cars sits well at present with all heights (from the wheel arch centre - unreliable) equal. I plan to wheel/corner weights soon and adjust accordingly.