How to rebuild your front master cylinder


Step-by-step tutorials on how to maintain and fix your GL1100
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KCwing
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Re: How to rebuild your front master cylinder

Post by KCwing »



Will this DIY article work for a 1978 GL1000?

Thanks!



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Phunnybone
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Re: How to rebuild your front master cylinder

Post by Phunnybone »

My 1200 LTD (#3) master cylinder innards didn't quite look like this, and the original clip DID NOT come out willingly (but the replacement went in easily. Solved the front brake locking up problem.

frodeem
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Re: How to rebuild your front master cylinder

Post by frodeem »

I am trying to build the front master cylinder. So far I have managed to do everything except the rubber boot from step 21. I followed the instructions to insert the boot over the piston and made sure the top of the boot sits in the channel around the top of the piston. I cant seem to understand the directions for the bottom of the boot. I have attached some pictures to show what I mean. Hoping someone can help me. Appreciate your help.
















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WingAdmin
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Re: How to rebuild your front master cylinder

Post by WingAdmin »

I'm not entirely sure from the angle of your pictures, but it looks like the boot might not be seated in the groove in the master cylinder. I found that it was easiest to push the base of the boot down around the piston and get it seated into the groove in the master cylinder, then work the top of the boot around the end of the piston and seated in its groove.

frodeem
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Re: How to rebuild your front master cylinder

Post by frodeem »

WingAdmin wrote:
Mon Jan 29, 2018 8:52 am
I'm not entirely sure from the angle of your pictures, but it looks like the boot might not be seated in the groove in the master cylinder. I found that it was easiest to push the base of the boot down around the piston and get it seated into the groove in the master cylinder, then work the top of the boot around the end of the piston and seated in its groove.
Is the groove above the circlip?

frodeem
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Re: How to rebuild your front master cylinder

Post by frodeem »

WingAdmin wrote:
Mon Jan 29, 2018 8:52 am
I'm not entirely sure from the angle of your pictures, but it looks like the boot might not be seated in the groove in the master cylinder. I found that it was easiest to push the base of the boot down around the piston and get it seated into the groove in the master cylinder, then work the top of the boot around the end of the piston and seated in its groove.
Thanks WingAdmin, I was able to do it after I removed the top of the boot. Appreciate the help.

ptrumblejr
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Re: How to rebuild your front master cylinder

Post by ptrumblejr »

i love this article the pictures are extremely helpful

I have a problem i hope someone can tell me where i went wrong. i rebuilt my front master cylinder and it worked just fine on the bench. Squeeze the handle it goes in release the handle it springs back. Perfect, I thought. As soon as I put back on the bike i put brake fluid in the cup, squeezed the handle and does not return. sticks in the compressed position. i removed it opened it back up everything was good. return port open, works great on the bench again. put back on the bike and it doesn't return.

Can someone tell me whats going on before i start throwing tools? Thank you in advance. :cry:

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Re: How to rebuild your front master cylinder

Post by WingAdmin »

ptrumblejr wrote:
Tue May 19, 2020 10:17 am
i love this article the pictures are extremely helpful

I have a problem i hope someone can tell me where i went wrong. i rebuilt my front master cylinder and it worked just fine on the bench. Squeeze the handle it goes in release the handle it springs back. Perfect, I thought. As soon as I put back on the bike i put brake fluid in the cup, squeezed the handle and does not return. sticks in the compressed position. i removed it opened it back up everything was good. return port open, works great on the bench again. put back on the bike and it doesn't return.

Can someone tell me whats going on before i start throwing tools? Thank you in advance. :cry:
Doe sit work if the banjo bolt is cracked, so that there is no pressure in the brake line? Or is it as soon as there is brake fluid introduced, the spring no longer pushes the piston back out?

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Re: How to rebuild your front master cylinder

Post by ptrumblejr »

As soon as i put fluid in the spring doesn't push it back.

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Re: How to rebuild your front master cylinder

Post by WingAdmin »

ptrumblejr wrote:
Wed May 20, 2020 6:38 am
As soon as i put fluid in the spring doesn't push it back.
I would have a look at two things:

- Check that the inside bore of the cylinder isn't corroded or otherwise damaged - it needs to be fairly smooth
- Check that the rubber sealing ring on the piston was put on the right way around - it's tapered one way:

Image

ptrumblejr
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Re: How to rebuild your front master cylinder

Post by ptrumblejr »

I suppose the cylinder wall could be damaged but it was a fresh rebuild kit with a new plunger and seal the was on the right way. I have an aftermarket assembly on the way. Im hoping that gives me brakes so i can ride.

ptrumblejr
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Re: How to rebuild your front master cylinder

Post by ptrumblejr »

so after my rebuild attempt failed, i purchased an after market front master cylinder assembly. bolt on, bleed and go. or so i thought. its moving fluid and my caliper is moving as releasing but its not solid braking. plunger goes full depth and brakes only lightly apply. the lever never gets tight. am i missing something? since the foot pedal is connected to both front and rear calipers is the one connected to the handle supposed to be soft? i have never owned a Goldwing before so i dont know what to expect.

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Re: How to rebuild your front master cylinder

Post by WingAdmin »

ptrumblejr wrote:
Wed May 27, 2020 5:06 pm
so after my rebuild attempt failed, i purchased an after market front master cylinder assembly. bolt on, bleed and go. or so i thought. its moving fluid and my caliper is moving as releasing but its not solid braking. plunger goes full depth and brakes only lightly apply. the lever never gets tight. am i missing something? since the foot pedal is connected to both front and rear calipers is the one connected to the handle supposed to be soft? i have never owned a Goldwing before so i dont know what to expect.
It should not be soft. If it is soft, that means something is compressing. Either you still have air in the system, or you have a hose that is failing and stretching.

Try pumping up the handle several times until it gets as firm as it's going to get, then hold it down tight, and use a bungee or rope to tightly hold the brake lever tight on. Leave it sitting like that overnight and see if it makes any difference.



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