The ZG1200 Voyager Xii and the ZG1000 Concours use the exact same driveline design and tooth pattern for the driveshaft front coupling (at the transmission output), and for the rear wheel hub coupling (at the final drive output). The engaged teeth within these two couplings see virtually no sliding action, but see almost exclusively fretting-type action (and then only of a thousandth of an inch or so) as the teeth engage back and forth as torque is applied one way with throttle and then reversed with braking.
A lot of folks likely only lubricate the wheel hub teeth when they change rear tires, and probably almost nobody pulls the driveshaft out and lubes the front coupling (the entire rear swingarm has to be pulled off to get to it). When talking about driveline lubrication, the manual makes a reference to "High Temperature Grease", which could end up being several different NLGI grades, given the descriptions on tubes at the auto parts store. A common grease that probably a lot of folks use is NLGI #2, often with it's distinctive "red" color.
Owning both of these bikes, my experience with these couplings is that upon disassembly, the grease often has long been slung out of the teeth, with the teeth dry or virtually dry by the time the rear tire is worn out. I have even seen fretting corrosion beginning to occur between the tooth surfaces from the dryness. So how can this be improved given longer tire life's and longer service intervals???
These coupling tooth designs Kawasaki uses are most similar to industrial Gear-couplings, and still similar, but not quite as much, to industrial Grid-couplings. In both of these styles of couplings, an often-specified type of grease is FALK-brand Long-Term-Grease (LTG). FALK is an industrial coupling manufacturer. In these design couplings, it is a no-no to use NLGI #2 or other "thinner" greases, because at speed, the rotational forces in the coupling will eventually sling the grease out (ever seen a driveshaft coupling guard absolutely coated in grease??), until the coupling runs dry, and then it proceeds to rapidly wear out and self-destruct. I once made this mistake, the result was a 3" dia. x 24" lg. driveshaft rotating at several thousand rpm being thrown about 20ft across a room and doing a good job of trying to embed itself into a concrete wall!!
The reason the FALK LTG grease works is that it is thicker and much more tackier than any of the common multi-purpose greases, which is why is stays inside the coupling and "hangs" onto the rotating teeth so much better. Given the similarities of design and application, this makes the LTG a fantastic grease to use in these two coupling joints.
Anyway, a person can buy a tube of this grease from about any industrial drive & bearing component supplier (like Motion Industries, etc.). However, a tube of FALK LTG is expense and would be several lifetime-supplies worth. An easier, and cheaper, way to get LTG grease is to go on Ebay and look for someone selling a NOS FALK coupling grid and look for the little packet of LTG grease that typically comes with it. Buy it (got mine for $10), throw the coupling grid away, and keep the grease packet. The grease packet will lubricate at least a half-dozen wheel drive hubs and driveshaft front couplings.
It should be noted that the splined-joint at the rear of the driveshaft (at the final drive input) is a true sliding joint with applicable fine-splines. There are two O-rings within this joint that are meant to retain the grease, so using NLGI #2 "red" at this point is a good and cheap choice, just don't pack the joint completely full. So far, I have seen no issues with this joint ever being found dry when taken apart.
So there it is, hope this helps someone out!
