Driveshaft prices are dropping

[Grumpy Goat]

Hi Grumpy - been a while since I visited this site - apologies!

I haven't heard of problems with the RS driveshaft, can you give me further information? Is it a mileage problem?

Welcome back.  

Officially - as in "from BMW Motorrad" - there is no problem, per se, with the driveshaft on the RS (or the GS) or any other water-cooled boxer. That does not mean that there is not a problem out in the field. 

Several owners have experienced failures of the driveshaft universal joint (yoke) while the driveshaft is under load, i.e. when the bike is being ridden. These catastrophic failures often then cause the shaft to whip around inside the shaft housing / single-sided swingarm until the bike is brought to a standstill. By then other components would have been damaged, including, in one case I have heard, damage to the transmission. I have not heard of any accident / loss of life secondarily caused by the failure of the driveshaft leaving the rider in a dangerous situation on the road.

Many people have also reported rusting of splines at one or both ends of the cardan driveshaft which is - to my mind - a separate and unrelated issue to the one above, and is not a problem to the same extent. In my opinion it is a maintenance issue and not a material issue which I suspect the yoke failures to be.

BMW Motorrad has attempted to address the latter issue - the rusting splines - via a service bulletin (not a recall) in which some owners of newer model GSs and RTs are advised to bring their bikes in for inspection and potential fitting of a small one-way "duck-bill" drain valve on the underside of the swingarm at the lowest point. This allegedly to help drain any water or condensed moisture from the swingarm thereby allegedly mitigating the rust at the splines. I have my doubts as to the efficacy of this valve but it is what it is. During that inspection, I have read that in some cases, driveshafts have been replaced leading one to wonder ....  

Point is, they are silent on any other issue regarding the driveshaft. Also worth mentioning, owners of bikes of similar model and year where the yoke failures have occurred have not been included in these service advisories regarding the inspection and fitting of the drain valve. It is almost as if they concur that these are separate and unrelated issues.

All the while, and as far as I am aware, BMW Motorrad does not specify that there is any need for periodic inspection or servicing of the driveshaft since the driveshaft itself is not a serviceable part, i.e. the universal joints are not re-greasable.

So, in summary, depending on who you listen to, the potential "problem" is either material failure of the cardan shaft itself or rusty splines. As I said before the latter is - to me - not a "problem" but is a maintenance issue that someone should be doing, and in my case that someone is me.

As for the failures of the yokes on the cardan shaft, it is not a problem unless it happens to you or to a "significant number" of people. How significant is significant? If it happens to 20 people is it significant? If it happens to one person who has well maintained his bike per the manufacturer's recommendation only at the dealer, and if this failure happens in the middle of an intersection where he can't get out of the way of oncoming traffic and he is killed - is that significant?

Then, mysteriously, a new driveshaft (part number change only??) has appeared in the fiche for our bikes and for 80% cheaper than the previous part.

Sorry for the long-winded response, but to me this is a problem that could happen to anyone one of the thousands of RSs (and GSs and ...) with a similar designed cardan shaft. The only way to mitigate the risk is by periodic inspection which I (and a few others) choose to do. For more on that I invite you to visit my Youtube channel and watch the videos of my experience on this issue. They are in the RS Maintenance playlist, starting with this one: