rear brake master cylinder replacement


Information and questions on GL1100 Goldwings (1980-1983)
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Tipsy McStaggers
Posts: 39
Joined: Thu Jan 04, 2018 10:45 pm
Location: Atlanta, Ga.
Motorcycle: 1980 GL1100

rear brake master cylinder replacement

Post by Tipsy McStaggers »



I tried rebuilding mine with a K&L kit, but the front seal doesn't hold. Leaks when under pressure during bench bleeding. Anybody ever retro-fitted one from another model? Anything close enough to replace it with? Would like to get something new or remanufactured. thanks



Tipsy McStaggers
Posts: 39
Joined: Thu Jan 04, 2018 10:45 pm
Location: Atlanta, Ga.
Motorcycle: 1980 GL1100

Re: rear brake master cylinder replacement

Post by Tipsy McStaggers »

Took the master cylinder apart and the rubber seals from k&l kit seemed like they got soft and mushy and lost there shape. Re-used the old front seal but couldn't find the old rubber cup that fits over the spring so used the new one(was flimsy and hard to get back in). Put system on bench vice and ran attached brake line into reservoir and primed it so line would be full. Then with caliper piston half out filled caliper with fluid then attached line. After having everything connected I used a c-clamp to try and push the piston back in but it wouldn't budge, too much pressure. I released bleeder valve and pushed piston in some then closed valve. Was able to push plunger but piston just kinda just pulsed out a little then back in after letting plunger return. It doesn't pull any fluid from reservoir and push piston out like it should. Is the rubber cup that goes over the spring not doing it's job? Thanks, sorry for long post

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newday777
Posts: 1882
Joined: Tue Jan 11, 2011 5:21 pm
Location: Milford NH summer/fall & Oceanside, CA winters(N San Diego) with lots of miles riden between
Motorcycle: 2008 Cabernet Red. Level 4

1983 GL1100A Wineberry 36,000 miles

1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: rear brake master cylinder replacement

Post by newday777 »

Sounds like you are using the wrong kit. There were 3 different rear master cylinders on the 1100 series wing depending on your year.(you didn't say what year you are working on...)

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