My adventure girl Mystique started leaking copious quantities of fork oil out her right side fork seal about 4 weeks ago so the order parts routine kicked in. Since we were out in Canada 2 weeks ago On Mistress (K1200LT), this was not a rush but since the smoke has filled the valley and has finally let up it seemed a good time to work up some courage and tackle this.
I relied a tonne on the "Chain Gang" FAQ, the BMW shop manual, and the A&S BMW for their exploded parts diagram to make sure all the parts were accounted for and assembled in the right order. I'm an exploded diagram kind of guy when trying new repairs.
First things first was to prop her up with a jack on the protection guard to lift the front wheel up enough to get clearance for un-mounting. Once up, it's time to remove the brake caliper and ABS sensor, clear the cable guides, and tuck them around to rest on the engine guard.
Then off comes the lower fender/fork stabilizer brace assembly and the only thing left is to loosen up the forks from the triple tree. You need to remove the cap (lifts off easily) and slide each fork up about 6mm up in order to leverage a dowel under the handlebar and press down in order to free up a c-clip spring (leverage out with a very small flat-tip screwdriver). Once the c-clip is free, slowly release up the spring retainer and then you can loosen up the three bolts that clamp the fork and slide out the fork.
I didn't dump the oil until this point and inverted the fork to release most of the oil, then removed the drain bolt from the bottom and let the oil drain from there as well, then remove the spacer tube, ring, and spring.
With the oil removed, I thought this a good time to remove the fillister screw that holds the upper and lower assembly together but it just turned in itself as the screw had jammed in the pipe for some reason. Looking on the net to see if others had this problem (yes) and if they had a solution besides drilling, cutting, or torching/heat, air-wrenching (this seemed to be the answer from most) and one rather resourceful reply suggested tapering a wooden broom handle, inserting it into the fork up to the pipe, turning it upside down and rapping the fork and handle combo down on the ground and then under pressure using the hex-head socket remove the screw.
It worked on both!
With the ability now to separate the two, I removed the dust cap and the inner seal clip. To remove the inner seal it is said to pry it out but I found that if you put the lower fork in a vise where the brace mount is you can use the inner fork as a slide hammer and with a couple outward pulls knock out the inner seal, washer, and bushing thus separating the forks for cleaning.
While apart, I cleaned out the threads on the pipe that had some kind of thread-locker on them (this is why they bound like they did) in the pipe and worked the bolt to makes sure it would install easily, then I reversed the assembly up to installing the bushing and inner seal. I used a flat-bottomed punch and a hammer, and lightly worked in the bushing using the flat washer as a tap plate and seated it, then gently did the same with the inner seal with a plastic dowel so I would't scratch the stanchion.
Assembling the rest of the springs and washers, I then slid the fork up into the triple-tree to it's 6mm mark, added the 600ml of Bel-Ray 15w fork oil, and pressed in the spring retainer and c-clip, slide the forks down and align, put the fork stabilizer, wheel, caliper and ABS sensor back together and tested with flying colors!
First time though a fork set like this, feeling pretty good about it all.
