Rear brakes sucking air


Information and questions on GL1800 Goldwings (2001-Present)
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DonCal101
Posts: 2
Joined: Wed Dec 07, 2011 9:13 pm
Location: Placerville, CA
Motorcycle: 2002 GL1900A

Rear brakes sucking air

Postby DonCal101 » Thu Jan 01, 2015 1:02 pm



I have a 2002 GL1800A which I have owned since new, 80,000 miles. I commute about 80 miles daily on it. After thoroughly bleeding the brakes as per the shop manual (no power bleeder) the rear brakes are great for about 3 weeks. Then the brake gets spongy and has longer travel, eventually to the stop. When I bleed it again, after having to refill the pedal reservoir at least 3 times, I get lots of tiny bubbles, like a foam. Then things are fine again for another 3 weeks or so. Any guesses as to where the air might be coming from?



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Aussie81Interstate
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Joined: Thu Nov 27, 2014 2:34 am
Location: Penrith Australia
Motorcycle: 1982 CX500 Turbo (restoration project)
1981 GL1100 Interstate (sold)
1988 GL1500

Re: Rear brakes sucking air

Postby Aussie81Interstate » Thu Jan 01, 2015 4:44 pm

Bleed nipple may not be sealing correctly - or you have a bad/leaky fitting in the hoses.

Did you install new crush washers both sides of each fitting for the new lines?

If there are tiny bubbles you have air in the system - any signs of leakage ?

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jinx
Posts: 252
Joined: Sat Jan 30, 2010 11:42 am
Location: Mechanics,pa
Motorcycle: 2006 gl1800

Re: Rear brakes sucking air

Postby jinx » Thu Jan 01, 2015 4:54 pm

This is going to be some what vague and I apologize for that. If I remember properly there is a high spot in the rear brake system that doesn't get bleed properly with the factory procedure. If you check some of the other sites you may
find the procedure to bleed the rear brake system and remove the trapped air in the high spot.
I think if you search for spongy brakes on gl1800 you will find the post.

Sorry that is the best I can do for now.

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DonCal101
Posts: 2
Joined: Wed Dec 07, 2011 9:13 pm
Location: Placerville, CA
Motorcycle: 2002 GL1900A

Re: Rear brakes sucking air

Postby DonCal101 » Fri Jan 02, 2015 12:08 pm

Thanks. I've tried raising the back side of the bike to make the rear caliper the highest point. No visible fluid leaking from the rear master cylinder, delay valve, front calipers, anti- dive unit. It seems to be letting air in but no fluid out. It seems like it must be a long way from the rear caliper, because it to takes so much bleeding before I see the bubbles.

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jinx
Posts: 252
Joined: Sat Jan 30, 2010 11:42 am
Location: Mechanics,pa
Motorcycle: 2006 gl1800

Re: Rear brakes sucking air

Postby jinx » Fri Jan 02, 2015 1:46 pm

I did a search but could not find any direction but some one mentioned loosening a banjo connector . They provided a pic but it wasn't very good. But it looked like it was under the right side cover.

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PastoT
Posts: 294
Joined: Sun Jul 01, 2012 9:20 pm
Location: Mt Home, Idaho
Motorcycle: 2002 GL1800 (107k)

Re: Rear brakes sucking air

Postby PastoT » Tue Feb 10, 2015 3:05 pm

I have an 02 that I recently started double pumping the rear brake to get full affect. Rebleeding the rear brake circuit did cure it but I had the same issue last spring and rebleed the system then as well. I suspect the one or more bleed nipples worked loose ever so slightly. next time I work over the breaks I'm adding a sealant or weak Loctite to each. There was mention of two additional bleed points for the factory rear brake bleed instructions... yes there are two points where the rear are linked to the front and both points are along the left fork. So after bleeding front left upper, front right lower, rear lower, the anti-dive and rear upper you have these two left. Both are points where bubbles can rise up to.

Bleed point # 6 is the lower junction box at the upper left side of the frame (when facing forward). To locate it follow the brake hose up from the secondary master cyclinder (above the left brake caliper). For this you will need a wobbly ended 12mm flare nut wrench. with pressure on the brake pedal crack it loose, listen and watch for brake fluid to spray then tighten before the pedal is released. make sure its is snugged up before moving on (this is the one point I think I could have sucked air back in). This is a bear to get at and work on so have patience.

Bleed point #7 is the Banjo bolt on the secondary master cylinder. Again pressurize the circuit and crack the bolt loose and Look and listen for air/fluid spray and retighten before releasing the brake pressure.

I call this the Rocky Bleed as I understand it was published in another forum by a beloved but banned member who is full of great maintenance and upgrade knowledge and some may refer to as snarky! It has proven itself worth while to me each time I've flushed my brakes; I just left something unsealed. I literally just flushed my rear brakes last week and they are much better, I went back and checked my nipples again after a long weekend ride just incase! :lol:


Tom, in Mountain Home, Idaho
2002 GL1800 (Illusion Red) Non-ABS, 108k miles
Retired Air Force

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