I just bought my '87 K100 LT with 36,100 miles, what a great ride, until-------it went crunch! I was rolling to a stop, down shifted into first and heard that awful sound. No power to the rear wheel, just a grinding sound like metal against metal coming from the drive shaft area I think. I am so bummed out! I have read some info about these bikes having spline problems, but with only 36,000 miles, come on! Any ideas out there? Any info about what you may think it is and the possible cost of repair would be greatly appreciated.

Well, that could be. To find out you would have to remove the final drive and see what it looks like at the spline end. It is not too hard to remove. One end of the driveshaft splines will be exposed at that point, and you should be able to remove the driveshaft to view the other end.

Sorta sounds like a cactus spline to me. Remove the rear drive from the swingarm and inspect it.



If it needs just the shaft it can be repaired but if the spline on the drive is R/S then source a used drive.

Sorry for your problem. Spline failure after 36000 miles is possible if regular spline inspection and maintenance was not performed by the PO. The splines must be regularly inspected for wear and lubed every 20000 miles (I believe). Better yet is spline lube every second tire change (about 10000 miles).

There are a few companies that can repair the drive shaft splines and final drive. Bruno's in Canada can do an excellent job. For around $750, he will:

• Beveldrive disassembly / Assembly

• Rebuild pinion spline extend 7/16" (11 mm) and heat treated.

• New pinion seal on assembly.

• Will check the Bearings and reshim if needed at the same time.

• Will call if the Bearings are worn and need to be replaced.

• New Drive shaft spline collar with intergraded grease reservoir. (heat treated )

• New U-joint

• 4 ounce Moly paste spline lube (refill drive shaft grease reservoir at every rear Tire change or Yearly)

Bruno's Machine & Repair
HWY 554 # 47
RR1 Iron Bridge Ontario
P0R1H0 Canada
phone / fax 705 843 0822
www.brunos.us
brunos@brunos.us

A new drive shaft and final drive from BMW will be big bucks -- around $1800. Forget that route. Parts from Beemerboneyard will be half the price of new, approaching the price of a rebuild but I think a rebuild is the better option. The benefits are that (1) you are getting splines 11mm longer than OEM meaning more surface contact and less wear (2) grease retention cup meaning no loss of lubrication into the drive shaft and grease is kept where it does the best job (3) hardened splines meaning less wear (4) new seals meaning reset maintenance period for that aspect of your motorcycle.

I'm planning on sending mine in this winter after the riding season.

It's a shame that BMW sold their final drive as maintenance-free. It is not written anywhere to inspect and/or lube the splines, but as already mentioned, it is HIGHLY recommended. Best to do once the rear wheel comes off for a tyre change and it is very easy to do as well...

Alex_GER wrote:It's a shame that BMW sold their final drive as maintenance-free. It is not written anywhere to inspect and/or lube the splines, but as already mentioned, it is HIGHLY recommended. Best to do once the rear wheel comes off for a tyre change and it is very easy to do as well...

It's not mentioned clearly in the owner's manual however, in the maintenance schedule chart used by BMW technicians, there is a service item "Lubricate applicable splines every year* (input shaft, paralever, driveshaft)
Motorcycles produced from 1990 onward, lubricate every 40,000 miles.)". The asterisk after year means "bill as a separate item". So, BMW does recommend inspecting and lubricating the splines. Maybe BMW Sales communicated the benefit of low maintenance to potential clients during the sales cycle, contrary to this schedule.

And, yes, the final drive spline inspection is very easy to do. The first inspection will be the longest as you gain experience and understanding as to whats involved. After that, the process takes less than an hour to do. The transmission and clutch splines inspection/lubrication process is much more involved and takes longer (have to disassemble the drivetrain to get at these splines). The saving grace is that spline wear in the transmission and clutch area is less than in the final drive, and the service interval for those areas can be drawn out.