Originally Posted by FatStrat
...The question is... "does properly setting the preload result in the longevity that should be expected"? Is there any anecdotal, or otherwise, information that points to evidence that this potential problem can be corrected with proper assembly, and an extended service life of the unit be gained?.....
Okay, here we go again, but since you asked.....
My well considered conclusion is that K1200LT final drive failures are a result of assembly and/or manufacturing errors, not a failure of the basic design of the drive.
In my opinion a preemptive rebuild makes the most sense for early model bikes, 99-03 since those are the bikes that had most of the crown wheel bearing failures. 2005s are worth looking into because of the incidence of the spun tapered roller bearing in this year group. Also, once I started routinely looking for the creeping input pinion needle bearing race, I realized that is a fairly common finding, but doesn't result in catastrophic failure that often and not until relatively high mileage; this isn't a problem that I would open a drive to look for specifically, but any time a final is opened the creeping input pinion needle bearing race should be checked for.
My personal experience with rebuild success isn't as good an indication of the value of a preemptive rebuild as is the information that was garnered over several years from good folks on this board who are professional mechanics or mechanical engineers and in some cases were both professional mechanics and mechanical engineers during their careers. The mechanical engineers were unanimous in one central fact: excess pre-load on the crown wheel bearing will lead to premature failure. This information combined with my observation that virtually all final drives with failed crown wheel bearings were found to have excess pre-load led to the conclusion that excess pre-load was the central factor in premature failure.
I should try to recall all the folks who contributed to this effort over the years. The problem with a list like this is that some folks will be left out, so with the caveat that this list is not all inclusive, and apologies to those omitted, here some of the contributors to the effort to understand final drive failures, in no particular order: dshealy, dman, realwing, saddleman, jzeiler, K100Dennis, neil_peterson. Thanks to all those who took the time so share their knowledge and experience in thoughtful posts on the subject.
(To those lesser contributors, the shoot from the hip gunsmith who was going to build a better bearing in his gun shop, and all other "better bearing" builders, to those who would convert the K1200LT to chain drive, etc., thanks for the entertainment.
Of the 50 or so final drives I have rebuilt, I know of only one that went on to fail again. It was off an RT, not a K1200LT. While I don't know why this final drive went on to a repeat crown wheel bearing failure I would not interpret it as an indication that proper rebuild does not improve the future longevity of a drive. I suspect I must have done something to damage the bearing during assembly; the rebuild of this particular drive is lost in my memory, but during my learning curve I had occasion to get a crown wheel bearing jammed in the cover due to misalignment during final assembly and this could have caused micro-stress to the bearing setting the stage for failure. The rider of that RT was understanding, stated that he was an Iron Butt rider and rode his bikes hard, however, I do not think riding habits caused the repeat failure; when rebuilding this RT final drive the second time, the pre-load setting did not need changing.
In my opinion, if a K1200LT final drive preemptive rebuild didn't cost time or money, it would always be worth doing; consider it like maintenance work in aviation. Rather than the "don't fix what isn't broken" approach, in the case of early model K1200LTs I consider a preemptive rebuild to be preventative maintenance.
The decision to rebuild is like buying any insurance policy, what do you consider your risks are? If you always ride close to home your risk is different than if you are planning a long trip where a vacation could be ruined by loss of days, money, and hassle.
No doubt there are brands and models of motorcycles out there with better reliability reputations, but remember that the vast majority of K1200LTs are problem free. People post where there are problems, not when things are going fine. And for those of us who love the K1200LT, there still is nothing out there that compares in comfort and performance in a long distance touring motorcycle. The K1200LT is a classic and remarkable work of engineering, and it still has no peer in its class.
Hope this helps in your decision making.
Addendum: If you have found a low mileage 2005, at the right price I say jump on it.
If I found a 2005 locally with low mileage, I'd consider upgrading my 2000 to an 05.