bleeding front brakes


Information and questions on GL1000 Goldwings (1975-1979)
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BSArider
Posts: 30
Joined: Fri Jul 22, 2016 1:05 pm
Location: Hillsboro NH USA
Motorcycle: 1978 GL1000
07 Suzuki Bandit
61 BSA A10
71 Norton Commando

bleeding front brakes

Post by BSArider »



Bleeding out my front brakes after a caliper and master cylinder overhaul. I can't seem to get any kind of flow beyond the master which I bench bleed. At this point I have the brake lever zip tied most of the way back and am getting a stream of very tiny air bubbles back into the reservoir. I plan on leaving it overnight and see what happens. Is it normal for it to be so hard to get fluid down to the calipers? I also know that I over stroked the master cylinder during both assembly and after it was installed on the bike, but never when it had fluid in it...(note to self..read the book FIRST :roll: ) Might I have done any harm that's causing bleeding issues?


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smittyboy734
Posts: 34
Joined: Tue Apr 12, 2016 7:21 am
Location: trenton,mi.usa
Motorcycle: 1978 gl1000..owner 70 cl70 .previously owned 81cb750k,76 cb500T ,78 kz650,71 H1500

Re: bleeding front brakes

Post by smittyboy734 »

not sure if any harm has been done to the piston seals, probably not,i recall having the same issue on my 750 k i went out to a cheap tool store (harbor freight) purchased a vacuum bleeder . have used it on all my brake rebuilds since. also recommend new stainless brake lines, good luck
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badandy
Posts: 79
Joined: Tue Nov 01, 2016 7:03 pm
Location: Weirton, West Virginia
Motorcycle: 1977 GL1000 Goldwing
1982 GL500I
1983 VT500 Shadow

Re: bleeding front brakes

Post by badandy »

I just did a rebuild of my front brake calipers and m/c. I use a vac bleeder on all my brake work. Works every time.
When using the vac bleeder wrap some Teflon thread tape around the bleeder screws being careful not to cover the bleed hole. This seals the threads so you aren't pulling air around the threads when you pull a vacuum on the system. Only crack the screw a 1/4 turn when bleeding.

A few things to do if you have no flow:

Break the banjo bolt loose at the m/c and gently pull the lever until you get fluid. Keep the lever pulled in when you tighten the banjo bolt. If not you will just suck air back in. Sometimes an air lock will occur at this junction and this is the best way to relieve it. If you are getting air bubbles that is a good sign that the air is escaping. Second is "slapping" the lever repeatedly for several seconds. This tends to dislodge any remaining trapped air. Also make sure the "relief" port in the m/c is clear or you will pump the calipers and they won't release because the fluid can't return to the reservoir. On some m/c's this port is very small and gets corroded shut after sitting for a long time. The hole on my particular m/c was large enough to actually see through it.
BSArider
Posts: 30
Joined: Fri Jul 22, 2016 1:05 pm
Location: Hillsboro NH USA
Motorcycle: 1978 GL1000
07 Suzuki Bandit
61 BSA A10
71 Norton Commando

Re: bleeding front brakes

Post by BSArider »

Thanks All-I used my vacuum bleeder to start and got nothing, but after much time pumping I have finally gotten flow to both calipers. Been a long time since I've dealt with a completely empty brake system. :o
sfruechte
Posts: 219
Joined: Tue Mar 09, 2010 12:53 pm
Location: La Crosse, WI
Motorcycle: 1977 GL1000

Re: bleeding front brakes

Post by sfruechte »

Just gravity should work on the front brakes. Worst case all you really need is a clear hose like a battery vent hose on the bleeder and pump away. Once you see the brake fluid in the hose, air cannot get back in. Turns bleeding car brakes into a one man job with no vacuum pump needed.


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