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1980 GL1100i Rear Brake Master Cylinder

4484 Views 19 Replies 13 Participants Last post by  jpenticuff
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Did some work on 1980 GL1100i Interstate and have a problem with the rear brake.

Rebuilt the Master Cylinder but the problem didn't go. Where canI find a Master Cylinder (w/Banjo connection) that won't cost an arm and a leg?

Any suggestions / hints would be appreciated.
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What is the problem with the brake? Some things look like a master but may be elsewhere.
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More Details,

The systemdoesn'thold pressure.

Flushed.

Bled.

Rebuild kit.

Tried Clamping Caliper and still doesn't hold pressure.

and ...The fluid has a grayish color.

No Leaks.



This is the kind that has a hose between the master cylinder and reservoir.



???
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Anyone know a reputable seller of Used (or new)Rear Master Cylinderfor a 1980 GL1100i?
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The gray colour is old brake fluid. I understand that the system you may have is linked front and rear so bleding the one cylinder will not help. You ned to turn your attention to the front end and bleed the front as well.

This has been discussed a few times on this forum and a search will show up the tips on how to do this belleding of linked systems
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Welcome to the forum, 80GL.

Yeah, always bleed the caliper farthest from the master cylinder first. That's been the rule forever. Any brakes,all thetime.
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This doen't have the connection to the front. I believe 80 and 81 were the only years. I read on one of the forums that 83 does.
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Yeah that's right only 83's linked..but back to your problem..the rubber hose maybe be bad..and expanding and taking all the pressure. Getting a replacement cheap is a eBay or breaker deal..and it's always a crap shoot or look here in the for sale section. But most brakes off the bike can't be tested so all you have is "it was working when removed" statements. SO save your rebuild parts you may need them.
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It's a bit of hike for you but Coopers Cycle in Franklin, NH usually has things like this, I got one last year for my 1982. When they take it off the bike they bolt the opposite end of the banjo and bleed it. That way the seals stay wet and you can see it pressurize by pumping the master.
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80GL1100iRydr wrote:
This doen't have the connection to the front. I believe 80 and 81 were the only years. I read on one of the forums that 83 does.
Hmmm, that does change things...

The gray fluid may be a clue. I'd make sure to get fresh fluid flowing through the calipers first. Do you have a bleeder or are you pumping?

Also, there may be somthing in the reservoir holdingthings up. Small particles do big things.

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He is right, his 80 goldwing does not have linked brake system, you should try with a vacuum pump
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yes use one from harbor freight for 20dollars or so i had a heck of a time bleeding the rear caliper out
i rebuilt the caliper and the master cylinder also so i went and bought one from harbor freight for 20 bucks kinda of handy to have anyway and it did the job in just 3 tries
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I am definately seeing a patern of bleed once, bleed twice, and even a third time is nice!! So I will try again, and use a vaccum pump. Thanks to all for the advice, I will keep you posted on the outcome.
_rydr_
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Flush it out with at least 3 full bowls of Dot 4 brake fluid. I use a Mighty-Vac to do mine and it works like a charm.
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One thing we overlooked is the tiny hole syndrome,.... In the master cyclinder there is 2 holes, one is large enough to see with the naked eye, the other you have to feel around to find,.... I used a wire off of a wire brush and poked around until I found the Tiny thole and cleaned it out the best I could,...... I also rebuilt my caliper which made a big difference, Actually had to do it twice because of the same problem you are mentioning,.. no pressure. Once I cleaned out the Tiny Hole, pressure built up,.... Bleed with new brake oil and what I did also was to hanga brick or something heavy overnight to help the air to escape thru the MC,..... Any way hope this helps,,.... one other thing is to put a little Teflon Tape on the Bleeders to help keep air out;) I think changing a T belt is a better Job to do,. bleeding Brakes is one of my least favorite jobs:X!! :pumpkin::bat::waving:Good Luck, Bob
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I have just bought a 1980 gl1100i and after it sat for a year i am getting no presure to the rear brakes. I have bleed them. I get fluid out of the bleeder valve but never get any presure. What am i missing? Thanks for any help.

jim
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Welcome to the forum for both of you new wingers!

I have found that you also have to go nice and slow to get plenty of fluid into the master. Down stroke count of 3,up stroke count of 4,wait 5 count. The holes are small and need time to push the brake fluid.

You might disconect the banjo from brake caliper,put fingers on both sides and you might find it easier to get fluid started from master.

Make it a family project and have your mate come help.
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jpenticuff wrote:
I have just bought a 1980 gl1100i and after it sat for a year i am getting no presure to the rear brakes. I have bleed them. I get fluid out of the bleeder valve but never get any presure. What am i missing? Thanks for any help.

jim
If you've pushed the piston into the caliper it takes quite a few pumps to get the pads onto the rotor.

How strong is the jet of fluid coming out of the bleeder?
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Hi 80GL1100iRydr,



I am in the process of doing a complete rebuild of my brakes - front and back. Everything non metal is going. Unfortunately, even the pistons - $$$$. I could not save a few of them and if I replace a few I will replace them all. Oh yes... the 82 is not a linked system with the front. That started in 83.



In any event, what they are saying about the return pressure equalization hole it true. Make sure it is clean. This will cause that problem along with locking the caliper. It sounds like you have air in your system though.



On your M/S there is the nipple that your brake reservoir line attaches to. It's plastic and is held on by two screws. Remove that (if you hadn't before for cleaning. There is an o-ring around it so it might be a tight wiggle to get it off. Once off, there will be two drilled holes there. Make sure you clean the o-ring seat before re-assembly. It will be full of crud.



One will be large as mentioned, and go right through to the inside of the M/C where the plunger is. The other hole looks like they started to drill it and then stopped. If you look carefully in the center of that you will see a much smaller hole... maybe .20 of a mm. That is the hole that needs to be cleaned. Take things apart and clean them with solvents and a if you have to a small piece of wire. Don't just poke it in there with things still assembled as it just pushes that crud into the boar of the M/C and will do damage somewhere else.



BTW, this is the same setup as is the front M/C as well with the little hole. You can see that just by taking that front reservoir cap off and looking carefully down the through the plastic holes to the metal of the M/C.



VERY IMPORTANT: There is one other thing that you should be doing as well that I have found out... replace that 8" piece of hose that goes from the M/C up to the reservoir. Trust me when I say it will rot out from the inside after nearly 30 years of corrosive brake fluid in it. That was happening to me and was turning may fluid black. I had replaced it all (the fluid) last summer.



Honda does not carry a replacement for this hose anymore. I had to go all over town to find an industrial supply company that has something that was compatible with brake fluid. Fuel line is not. That brake fluid is aggressive stuff. When I found it, it was on a 250 foot roll. I told the guy behind the counter that I only needed 8". He mumbled something about that was what his wife said, went out back and cut me 3 feet of hose and gave it to me. He wouldn't take any money for it.



I hope this helps...



Tim.
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It is coming out in a slow stream not jetting out.
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