I just replaced the king pins and bushings on my '48 Ford F-1, now the brake drums rub on the brake backing plate (mostly on the bottom) when driving. They do not rub when the wheels are lifted off the ground. I had the local machine shop replace and size the bushings. I put washers on the lug studs behind the drums temporarily to stop the rubbing. Any ideas as what is causing the rubbing? Thanks in advance for any help.