You don’t want to be one of those “I broke my final drive” guys
When is the last time you checked you rear suspension or the shaft on your BMW R1200GS? We’ve made a thorough inspection on our long term test bike (my 2015, 60,000 km) and we got a bit surprised when we removed the final drive. Beware, this operation is not included in the standard service schedule, so you must ask the service to do it.
The hidden enemy – corrosion
Besides changing the oil, the shaft-driven BMW models need special checkups from time to time. Although well hidden inside the rear wheel swinging arm, the drive shaft can rust. This happens due to the numerous heating cycles throughout various climate conditions. It might not seem like a big problem at first, but the newer models like the R1200 series feature a single unit-shaft, compared to the older R1150 that featured a detachable shaft joint. This means you'll have to replace the whole shaft in a worst case scenario.
The rust will not affect the shaft itself, but the problem kicks in when the rust gets to the seals and damages the needle bearings inside. When this happens, you have a serious problem because the shaft joint can break at any point and you'll end up postin photos on the internet when getting lost on a secondary road. That’s why a thorough inspection must be performed from time to time.
If you are a riding addict and you don’t care about the weather, the rust issue might show up a bit sooner than you think. The temperature-variation will be the biggest enemy for you. When it’s colder outside, and you ride for a couple of miles, the whole rear wheel assembly will heat up. This means only one thing: condensation will show up inside the swinging arm housing. You might think that the rubber boots that are fitted on the bike will stand against this problem, but even the rubber boots must be check for premature wear at least when replacing the rear drive oil (every 20.000km).
The maximum check-up limit stands at approximatively 30.000km or three to four years. To perform the job, you have to make sure you have the right tools otherwise see a mechanic for this job. There are 100% chances that your shaft shows rust traces because it comes with a fresh metal finish so it can cool itself more efficient, and as we all know fresh metal and water won’t go together pretty well.
Try to use a soft steel wool to remove the rust and apply high-temperature water-proof lube on the shaft and joint. This way it will stay nice and rust free until the next check-up. Clean the inside housing and check for any water that gathered inside. Make sure everything is nice and clean and apply a bit of silicone solution to the rubber boot so it will keep its flexibility for longer.