I had this happen with my Coronet. I did a complete 4 wheel brake job one summer all the way down to new brake lines. The car drove great all summer but when I took it out of storage the next summer the car would dive to the right. I took the drums off and noticed the right front shoes were dis-colored. I replaced the shoes and haven't had a problem since. It's been 9 years now. I'm not sure what got on the shoes, maybe something on my hands when I installed them? Maybe they were contaminated when I bought them? But I never found any hydraulic leaks.