So in another BMW engineering marvel, someone decided to attach one end of the rubber boot to the half of the ball joint that turns, and the other end to the half that doesn turn. When new, there's a rubber gasket inside the top of the boot which allows it to slide on the metal disk it's attached to until the grease dries out and then it just rips open from rotational torque. Poor design, in my opinion.

So off to the auto parts store (O'Reilly Auto) I went. They sell a two pack of universal replacement tie rod boots. One large and one small. If you cut them roughly in half, the top half of the large one will attach to the bottom of the ball joint and friction fit to the bottom of the disk where the old boot attached. The small boot will attach to the metal disc where the original boot attached and friction fit against the top of the bottom boot. So what I wound up with is two boots and a double seal on the ball joint. Total cost under twelve dollars and that included a tube of CV joint grease to service the ball joint. I'll post a couple photos later.

Here's the photos. You can see the zip strips attaching the boots to the ball joint. I don't think they are necessary if you cut the boots to the right height as that makes everything friction fit/compression fit, but I thought they would be a good idea to ensure a water-tight seal. Time for a beer.

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Great job coming up with a fix.

You can also order a replacement boot that is a bit thicker construction than the original BMW part on eBay at http://www.ebay.com/itm/BMW-Ball-Joi...item20cedcadb2 .

I installed mine and was very happy with it, bought another just in case...because if you have the part the one on the bike will never, ever wear out!