This is in regards to a 1992 K100RS, 16valve.  Well, I found a leak in the brake line from the rear master cylinder to the rear ABS module.  Of course, there are no lines in the country (USA) and I'd have to order it from Germany.

I've read around the forum and found a few custom brake line websites.  I'm currently looking here: http://www.venhillusa.com

I'm thinking of changing the connection at the rear master cylinder to a banjo connection.  It's the only one on the bike that isn't a banjo connection.  Would that be okay to do?  If so, I'll need to get the correct size banjo bolt for it.  I read around the forum that the front brakes are 10mm banjo bolts, but only read in one spot that the rear master cylinder is 12mm female thread.  What size banjo bolt should I look for with what type of thread?

I've got a line ready to order but need to select banjo bolt size, which, on this website, is only available as 10mm or 3/8".  The options are: 10mm x 1.00 Single-length, 10mm x 1.25 single-length, 3/8 x 24 (UNF) single-length, 10mm x 1.00 double-length, 10mm x 1.25 double-length, 3/8 x 24 (UNF) double-length.  I'm not sure any of these will fit the rear master cylinder.

Also, is it the same line as the k1100 has?  Would this work? (top right, part number 22144S.) http://www.motobins.co.uk/displayfinal.php?q=109&s=0&subs=109&model=K100&title=STAINLESS%20STEEL%20HOSES

I happen to know that the banjo bolt thread on the front calipers are a 10x1mm thread. I confirmed this yesterday as I was stripping a caliper down. I would therefore suspect that all of the brake line threads are metric so you can discount the UNF ones. If the rear is a 12mm then I would expect the thread pitch to also be 1mm rather than 1.25, but I could be wrong.
The parts diagram shows both rear brake pipes for an ABS equipped 16v as having banjo fittings on both ends and the washer/gasket as being 10mm. The BMW part number for the hollow bolt attaching the line to the rear master cylinder is 34321242205.
If you need me to go and take the footrest hanger of my bike and photograph it then let me know and I'll do it in the morning.
Hope this helps.

Yeah, I actually just looked at some parts diagrams on maxbmw and it shows both ends as banjo.  Mine is not, and I find that to be a little strange.  Mine is the same set up as the previous link I posted.  Either way, I ordered the banjo bolt and washers from the parts diagram for my bike so I should be good there.  Now to find a hose.

I could just order the hose from the same parts diagram, but I'd love to change it to a stainless braided hose.  Do the banjo connector sizes change drastically enough that a 12mm bolt would no longer fit where a 10mm normally would in those Venhill custom brake lines?

Just been down to have a look at my bike. It also has a straight fitting into the rear master cylinder. Seems that the parts diagrams may have something wrong.

FWIW: I've messed with a lot of K bikes and don't recall EVER seeing a banjo bolt into the rear master.

By the way, there are plenty of K bike brake line configurations that don't use a banjo bolt.  Like at both ends of the metal lines for the front ABS modulator.

They are esentially the same as a K1100 and dont have the banjo fitting. I put a Banjo fitting on my K1100 and to be honest it was a real PITA because of the towbar fittings and it had to be aligned perfectly for the other end to fit the ABS Module. I later got a venhill premade line from Motobins and it was an easy fit.  The banjo fitting is a normal 10mm fitting but I would recommend not to use it as it could destroy the ball flare fitting seat in the M/C if the bolt is a tad over length. I had to use 2 copper washers to prevent this happening to my M/C.

Well, I figured I'd order the hollow bolt from the parts catalogue on MaxBMW.  I ordered the what the parts catalogue described as the hollow bolt that threads in to the rear master cylinder.  Here's what came:



It seems to be an appropriate length in comparison to the existing straight fitting.  I'm going to order a line from venhill and give it a shot.  For now, I cut the leaky part of the hose off, hose clamped the crap out the hose to the straight fitting, and then welded the hose clamp to the 'nut' part of the straight connector, and no leaks.   :|   Can't wait for that new line to come..

That hollow bolt does indeed fit the rear master cylinder.  I got a brake line in from Venhill a couple days ago and put it all on with the banjo fitting on the rear master cylinder.  Everything is great!