rear brake (abs) bleeding woes

[jbeebe]

Let me start by saying hello! It's good to join another forum. Having only worked on Japanese (and a couple HD's), it's been interesting diving into the K75. Frustrating at many times...but interesting. The sticker shock of the price of parts is something that I am not enjoying, however! About a month ago I picked up a non-running '92 K75s, with abs. I spent about a month going through the whole thing to get it in touring shape. Here it is now, with the exception of the new seat cover which has been put on yesterday.







It didn't have any rear brake pressure so I disassembled the the rear mc and found the bore to be a little pitted. I opted to replace instead of rebuild and installed a new bmw mc. It bled great. As the procedure states, starting at the modulator and then going to the caliper, it built great pressure. I put about 50 miles on it since then. Today while out on another "shake-down" ride, I abruptly lost rear brake pressure and went home without the rear brakes.

It is not leaking from any connection and it refuses to build up any pressure no matter how much I bleed from the modulator and caliper. I used my compressor operated vacuum bleeder as well as doing it old school by hand. still nothing. I have also bled it from each banjo bolt. The mc pushed fluid out of it a couple of times until it too filled with air, so that coupled with it being new doesn't throw up any red flags. It doesn't appear that the modulator is getting any fluid from the MC, because the mc will not pump fluid to the modulator end of the hose connecting the two. The entire system is filled with fresh DOT4.

I'm just at a loss to what to try next. I know there are stories about hoses collapsing on themselves...but I've worked on/owned over a dozen vintage and newer motorcycles and have never encountered that. 

Any direction/help would be much appreciated!

Thanks.

[jbeebe]

Update: I think the supply line from the reservoir might be getting pinched off. I can get the system to bleed with the footpeg and MC assembly hanging loose. I'm trying to figure out how to route it while attaching the footpeg assembly without it pinching, but can't quite get it

[Paul_Waterloo]

Watching this thread, it is one of the last things I need to do on my K1100LT also. The brake grabs initially but real braking.

[jbeebe]

Update:

It was definitely the supply line routing. It seemed every possible position I would put it in would be squeezed off by the footrest bracket when mounted. This is how I had to route it so that it is pinched off the least:



The picture makes it look like it is sticking out and could get caught in your boot, but it's an illusion. It's not in the way.

Does anyone have a picture of how it's supposed to be routed???

[K1300S]

It goes entirely behind the foot plate.

[jbeebe]

It goes entirely behind the foot plate.

The circular silver colored swingarm plate seems to be blocking the hose from bending back and coming up closer to the modulator.

[Laitch]

Does anyone have a picture of how it's supposed to be routed???

It goes entirely behind the foot plate.

Here's a picture. Hose at red arrows.

[jbeebe]

Thanks Laitch, I couldn't quite get it turned that way without getting pinched on the swingarm. Maybe I'll give it another go

[Laitch]

Here's another example.

[Laitch]

The stock hose is ~18.5" long.