Check the flexible lines that connect to the caliper. If they are old, or the age is unknown, replace them. This does involve opening up the brake system so you will have to bleed the brakes. I have a pressure bleeder I bought from www.germanautoparts.com and I would never bleed any other way after having used that.
Check the rear sway bar links. If the little ball joints are loose or and dried out, these are cheap and easy to replace. Allan -- 1983 300D 1966 230
