I'd assume your '89 is the same as my '95. They come apart from the top. I made a tool by threading some 1/2 nuts on a piece of threaded rod then welding them in place. It's supposed to be 19mm (.748") but 1/2" nuts are .740" flat to flat and they worked fine. Length of mine is 17". Here's a pic. Click to make big.
TW Fork tool.jpg