Noticed the smallest of a puddle 'neath the swingarm which turned out to be brake fluid. I couldn't tell where exactly was the breach so I removed the peg plate and inspected the whole assembly. All hoses and connections looked fine.
I was examining the reservoir itself when out slopped a some fluid on my hands. I found the tiniest of holes, actually a missing shard of plastic. Strange, sez I so I gave the whole thing a squeeze and it burst open in my hand (brilliant, I know). 


My question: Since a replacement is in the cards, could I replace it with the later 'barrel' version that mounts on the upper frame near the battery? If 'could', is it a good idea? Seems like it'd be a bit more sheltered from sun, grime, salt, rain, etc. up there. New hoses, some rerouting, and voila?

I'm not certain of the answer to your question, but I don't see why practicaly any reservior would not work.  After all, its basically just a holding tank that gravity feeds to the MC.

With that said, if you want to go OEM, I have a spare.  I bought it new and installed it after my reservior disintigrated, just like yours.  It was only on the bike for a couple of months (and maybe 100 miles because I had the bike in various states of tear-down). I removed it when I put on rearsets for my cafe racer conversion and put in a whole different MC and lever set-up.  It's clean and in like-new condition.  I paid $30 for it, but make me an offer if you want it.  I'm open to a good deal since I'm never going to use it and would rather send it to a good home than have it cluttering my shop.  PM me if you are intersted.

This disintegration of the reservoir seems to be a common failure.  I suppose it's the result of exposure to ultraviolet light/ozone or what have you in an industrial environment.  My question: could/should this be dressed up with a protective coat of paint?
This weakness is a good argument for using DOT 4, which won't strip paint from the frame when the reservoir fails.

Use the barrel type. A longer hose may be required, but they came standard on my '88 K so no problems with compatibility.

I have done this. It is an advisable upgrade.

You need the bracket to hold the "new" res and will also need to drill a small hole  in the relay box for the screw that holds the bracket. The screw is the same as those for the relays.

There are two sizes of barrel res so make sure you get the correct bracket for the res you end up using.

duck wrote:You need the bracket to hold the "new" res and will also need to drill a small hole  in the relay box for the screw that holds the bracket. The screw is the same as those for the relays.

One of the very few things I disagree with you about. IMHO BMW's way of mounting the reservoir is utterly stupid, having to remove FICU, carrier and battery just to get at the reservoir mounting screw. Both of my rear reservoirs are mounted on brackets that clamp between the footpeg hanger and the gearbox. If I ever have to remove the rear hydraulic system the whole lot comes off in one chunk. Piccies will follow, but just at the moment the Blandit,  LFB and Brick 2 are all doing duty as tent-drying stands.

Agree, Dai, that the old position of the MC reservoir down by the right foot peg plate was not convenient.  BMW relocated the MC reservoir on later models behind the right battery cover, and changed the shape from square to round.  The reason for the relocation was to prevent reservoir self-destruction as what happened to the one in this thread.  It's location shields the reservoir from ultraviolet light that embrittles the plastic.

There's no hardware removal needed to get at the reservoir in the new location. It does require a longer hose to reach. The pictures below shows how the clamp is connected to the relay box.  The bolt holding the clamp is located under the starter relay. I think Duck was referring to this clamp.

Ah! That also explains the rusty lump I took off a spare relay box. The two arms were completely missing and all that was left were the two rivets and the bracket that screws to the box.