'10 R12GSA Rear Brake Leak

Good Day, All,

Just returned from an almost great 5 hr ride on my '10 GSA. About 3 hrs into the ride, noticed the rear brake starting to feel a bit spongy. At about hour 4, rear brake completely gone. Immediately pulled over. An inspection reveals the rear brake fluid reservoir completely empty. Rear brake pedal goes all the way to the stop with no resistance. There appears to be some seepage in the area of the bolt, pc 7 on fiche drawing 34-1649. I searched the forum as best I could but have not seen a similar issue noted. Before I put the bike up on the lift, I thought I would ask if anyone knows of anything to look for specifically or of any cautions I should know about.

My plan is to first attempt to tighten the subject bolt. If movement is noted, refill and bleed the brakes and watch it/test it/ride it to see if this fixes things. If no movement is noted, plan is to disassemble the joint, inspect for wear/imperfections, replace any needed parts and try her again.

If the reservior is empty and you only see "some seepage" keep looking.

Where did you find the referenced fiche drawing picturing bolt #7. Without the drawing it doesn't mean much.

If it is a banjo bolt fitting where the line connects either to the master cylinder or the wheel caliper then it might be able to be tightened.

sedanman said:

If the reservior is empty and you only see "some seepage" keep looking.

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Since it is empty and there isn't fluid left I would expect only a little seepage at this point. Who knows where it all dripped to going down the road.

PGlaves said:

Where did you find the referenced fiche drawing picturing bolt #7.

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Paul,

Sorry for not including that info. I found the drawing at the MAX BMW site.

http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=52024&rnd=08102012

Although not shown in the drawing, I am assuming the Pressure Modulator that is shown in the Brake Pipe Front ABS dwg, #34-1647, is where the two Brake Pipe Rear items labeled as '1' connect bridging between the rear master cylinder and the adapter labeled as item 3. I am also assuming this is how and where the front and rear brake systems are linked but remain hydraulically independent. This is just a guess.

PGlaves said:

Since it is empty and there isn't fluid left I would expect only a little seepage at this point. Who knows where it all dripped to going down the road.

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Those were my thoughts. I guess what I should do is to first refill/bleed the rear brake system and start looking for actual leak points with brake pressure applied instead of relying on the seepage I found as the source of the leak. I will then proceed with the repairs based on the results of this test/inspection.

Jim Rogers said:

I guess what I should do is to first refill/bleed the rear brake system and start looking for actual leak points with brake pressure applied instead of relying on the seepage I found as the source of the leak. I will then proceed with the repairs based on the results of this test/inspection.

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Just finished the pressure test using the rear brake pedal. Referring back to dwg 34-1649 from the MAX BMW fiche for R1200 GS ADV 10+ (www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=52024&rnd=08102012): sure enough, the leak is in the adapter (pc 3)/brake hose (pc 6)/hollow bolt (pc 7) joint. Using only moderate torque, no movement noted on the bolt. Because it is such a bear to get to, I think I will call Adventure BMW to see if it is a warranty item before I disassemble the joint.

That should be an easy fix.

The parts shown as "8" Gasket Ring are little crush washers. Replacing both of those with clean and undamaged sealing surfaces should fix it.

That fitting on the end of the line is called a banjo and bolt #7 is called a banjo bolt. It is hollow and has a hole cross drilled to deliver fluid inside the banjo.

To close out this thread:

Trailered the GSA to Adventure BMW in Chesapeake, Va on Tuesday. Walked in with my diagnosis and a copy of the subject dwg. (34-1649 from the MAX BMW fiche for R1200 GS ADV 10+ (http://www.maxbmwmotorcycles.com/fic...rnd=08102012):) with the suspect joint circled. Tim said, ÔÇ£That banjo joint is pretty much bullet proof. I have seen that adapter (pc 3) fail once.ÔÇØ Oh great! A failure so rare the part will have to come from Germany. Glad I have the RTP to ride. Confirmed the bike was still under warranty. Thursday afternoon, Nolan called to say she was ready for pickup. What? It was an adapter failure. An obscure part, not in their stock, and she is ready already? Picked her up Friday. Those folks at Adventure BMW are great and have always done me right. Stop by and see them if ever in the area.