Stretching Posterior Chain

[jynx]

I have a few flexibility problems. When I try to squat my bodyweight my heel comes up. If I throw at least 315 on the bar, I can squeeze to keep my heels down, which works. I really want to work on my flexibility in my calves, hamstrings, and lower back, however my static stretching isnt really cutting it. What can I do on my own to improve this? Thanks in advance.

 

[b_saan]

Straight Leg Deadlifts and Good Mornings are both good for ham/lower back flexibility... keep stretching before and after.