I just replace the UCA's on my car a couple of months ago and one of the upper bolts was rusted and stuck. I tried beating on it for a day or so and then got the idea of taking my trusty big C-clamp and a big socket to go over the bolt head and squeeze it out. It worked like a charm. It is hard to get enough swing with a hammer to move a bolt rusted to a bushing stuck in a hard piece of rubber sandwiched in a steel tunnel. A ball joint press might work too if you have one, but my big clamp was enough. Good luck!

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'82 240D Euro 68K and growing