How to rebuild your rear master cylinder


Step-by-step tutorials on how to maintain and fix your GL1100
  • Sponsored Links
User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Mon Jul 21, 2014 2:38 pm



gexxie wrote:Hi, I joined this site today and already I think I have my answer. I just rasied a question (viewtopic.php?f=16&t=23080) but this thread gives me the next step. If my brake is siezing even without me using the brake, it has to be the heating of the fluid with no chance to return through the master cylinder. I've changed everything else!. So, need to buy some more bits and plan my weekend to get this finally fixed. Admin - this is just the best site ever.... Thanks
Thanks for the kind words. This tiny brake fluid return port causes people more problems. Frequent (at least every other year) brake fluid flush/changes will prevent this from ever happening, so add this item to your maintenance checklist to avoid future problems.



robertdawber
Posts: 285
Joined: Fri Aug 07, 2009 9:24 pm
Location: Eliot, ME
Motorcycle: 1983 GL1100 Interstate

Re: How to rebuild your rear master cylinder

Post by robertdawber » Sat Mar 28, 2015 10:52 am

I am rebuilding my cylinder today. When I began to take it apart it was very, very hard to do. The circlip was so filled with corrosion and rusty crud. Before I began I read all of the comments. I found that being patient and using brake cleaner as Scott suggests-it worked out well.
My point is not to rush things.
Bob

robertdawber
Posts: 285
Joined: Fri Aug 07, 2009 9:24 pm
Location: Eliot, ME
Motorcycle: 1983 GL1100 Interstate

Re: How to rebuild your rear master cylinder

Post by robertdawber » Mon Apr 06, 2015 8:47 pm

WingAdmin wrote:They don't make new ones...so my advice would be to pull apart what you've got, scrape (gently) the rust and crud that's in there, and rebuild it using a commonly-available rebuild kit. Mine was completely full of rust and crap (as you can see in the pictures) and it cleaned up quite nicely. I think you'll be surprised at just how clean it comes out. Just use lots and lots of brake cleaner, and be gentle when scraping the channels clear - more than anything else, make sure you don't scratch the bore of the master cylinder.
I did all of this and then installed Speed Bleeders. Used my Mighty Vac. Everything seemed fine and today (My bike is still a work in progress and in the garage) I noticed brake fluid on the floor under the Master Cylinder. When I push the pedal with my hand I hear a squishing sound from the cylinder. Any thoughts?
Bob

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Mon Apr 13, 2015 12:06 pm

robertdawber wrote:
WingAdmin wrote:They don't make new ones...so my advice would be to pull apart what you've got, scrape (gently) the rust and crud that's in there, and rebuild it using a commonly-available rebuild kit. Mine was completely full of rust and crap (as you can see in the pictures) and it cleaned up quite nicely. I think you'll be surprised at just how clean it comes out. Just use lots and lots of brake cleaner, and be gentle when scraping the channels clear - more than anything else, make sure you don't scratch the bore of the master cylinder.
I did all of this and then installed Speed Bleeders. Used my Mighty Vac. Everything seemed fine and today (My bike is still a work in progress and in the garage) I noticed brake fluid on the floor under the Master Cylinder. When I push the pedal with my hand I hear a squishing sound from the cylinder. Any thoughts?
Bob
Was the bore of the cylinder clean and smooth? Did you get the piston seal on the right way around?

User avatar
stschil64
Posts: 1
Joined: Thu Jul 23, 2015 5:23 am
Location: Martinsville, IN
Motorcycle: 1983 GL1100I Insterstate

Re: How to rebuild your rear master cylinder

Post by stschil64 » Thu Jul 23, 2015 6:21 am

I just purchased an '83 Interstate. It needs some TLC, so I got it for a song. The rear master was seizing, as well as it having a seal leak on one of the front calipers. My question is this: I am an avid ammo reloader and have a pretty nice (and large) ultrasonic cleaner that I rarely use for brass cleaning. Would running these brake parts though a bath in the ultrasonic cleaner hurt them in any way?

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Fri Jul 24, 2015 8:31 am

The master cylinder and caliper are made of aluminum. You can certainly clean them in an ultrasonic cleaner, but just remember that they are relatively soft, and will pit easily if the cleaner is set too high, or if they are left in too long. The cylinders in particularly cannot survive pitting, as they will then leak brake fluid around the edges of the piston and seals.

User avatar
MaxRide
Posts: 4
Joined: Sun Aug 16, 2015 1:30 am
Location: Dayton, NV
Motorcycle: 1983 GL1100 Interstate

Re: How to rebuild your rear master cylinder

Post by MaxRide » Tue Aug 18, 2015 3:35 am

Hi all.

I just bought a GL1100i to supplement my Rebel and to commute to school with. The guy who sold it to me assured me everything was working properly and that the bike was good to go! I drove the bike home and immediately noticed the spongy front brakes...I get the bike up onto the stand and find out the rear brake is partially seized. It took a bit of time but I was able to remove the rear caliper and finally got the rear master disassembled. The brake was seized without the cylinder attached, so I guess the caliper is the issue.

I disassembled the cylinder anyways using this instruction manual. The amount of gunk on the outside made me think it would be easier to just buy a "new" cylinder, but once I got it apart the inside actually didn't look as horrible as I thought it would. The key to getting the cylinder apart for me was removing the clevis and then hooking the jam nut to the frame of my bicycle, in the slot where the wheel hub normally sits...one good yank with that method FINALLY released it.I cleaned and cleaned and cleaned and the cylinder is actually looking like it might be usable--however, while cleaning I did accidentally put a light scratch on the wall of the cylinder. At this point I'm wondering how screwed I am.

The scratch doesn't look bad, but it is there. At this point should I be looking for a new cylinder or should I put it back together and test it out first?

And by the way--thanks for a great write-up! Everything is going well so far except for the scratch...totally my fault and partially because I assumed a new cylinder was needed and wasn't being careful enough.

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Tue Aug 18, 2015 9:07 am

It really depends on the depth of the scratch. I would do your best to polish it (to round off the edges of the scratch and prevent them from wearing away at the rubber seal on the piston) and try it out.

If the scratch is more significant, try making up a small batch of J-B Weld, put a dab on the end of your finger, and smear it on the scratch. Then pull out as much as you can before it cures - the idea being that the J-B Weld will fill the scratch and cure, while the rest is "squeegeed" out. Once it's cured, polish the inside of the bore with a small piece of 1600 grit sandpaper.

User avatar
Wilcoy02
Posts: 911
Joined: Sun Nov 21, 2010 11:37 pm
Location: Marengo, Ohio
Motorcycle: 1983 GL1100 I purchased 3/16

1983 GL1100I frame with an 80 engine. poor boy installed with C-5 ignition--DIED in Grande Prairie Alberta Canada 8/15


98 valkyrie sold 8/16

Re: How to rebuild your rear master cylinder

Post by Wilcoy02 » Sat Apr 09, 2016 12:52 pm

step 23
The rubber seal

Does the closed end of the seal go toward the concave piece or does the closed end of seal go toward the screw type piston??

thank you

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Sat Apr 09, 2016 1:51 pm

Wilcoy02 wrote:step 23
The rubber seal

Does the closed end of the seal go toward the concave piece or does the closed end of seal go toward the screw type piston??

thank you
The seal isn't closed - it's a ring, kind of like a thick O-ring. It goes around the piston. If you look closely, it is a bit narrower on one end then the other. The narrow end goes towards the concave end of the piston:

Image

Subvetma1
Posts: 20
Joined: Mon May 27, 2013 9:29 pm
Location: Washington Court House, Ohio
Motorcycle: 1982 GL1I Interstate

Re: How to rebuild your rear master cylinder

Post by Subvetma1 » Sun Apr 17, 2016 10:29 am

May sound like a stupid question but would any kind of brake fluid work or do you need a specific tiype?

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Sun Apr 17, 2016 1:26 pm

Subvetma1 wrote:May sound like a stupid question but would any kind of brake fluid work or do you need a specific tiype?
You should use whatever the manufacturer calls for, with the exception that if they call for DOT3, you can use DOT4. It is fine (and probably recommended) to use DOT4 in an Goldwing. Do NOT use DOT5, it is not backwards-compatible with DOT4, and cannot be mixed in any way with DOT4.

Justinrobo54
Posts: 5
Joined: Mon May 30, 2016 2:02 pm
Location: Hemet california
Motorcycle: 1978 honda goldwing gl1000

Re: How to rebuild your rear master cylinder

Post by Justinrobo54 » Mon May 30, 2016 2:08 pm

I'm in the middle of rebuilding my rear master cylinder and on step 23. When compressing the spring and pushing the piston down I can't get it compressed enough to get the seal inside, or enough to get the washer in place and snap ring behind it. Any ideas on why that would happen?

User avatar
WingAdmin
Site Admin
Posts: 19311
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: How to rebuild your rear master cylinder

Post by WingAdmin » Mon May 30, 2016 8:14 pm

Justinrobo54 wrote:I'm in the middle of rebuilding my rear master cylinder and on step 23. When compressing the spring and pushing the piston down I can't get it compressed enough to get the seal inside, or enough to get the washer in place and snap ring behind it. Any ideas on why that would happen?
Did you lubricate both the seal and the inside of the cylinder first with brake fluid?

Justinrobo54
Posts: 5
Joined: Mon May 30, 2016 2:02 pm
Location: Hemet california
Motorcycle: 1978 honda goldwing gl1000

Re: How to rebuild your rear master cylinder

Post by Justinrobo54 » Tue May 31, 2016 6:05 pm

WingAdmin wrote:
Justinrobo54 wrote:I'm in the middle of rebuilding my rear master cylinder and on step 23. When compressing the spring and pushing the piston down I can't get it compressed enough to get the seal inside, or enough to get the washer in place and snap ring behind it. Any ideas on why that would happen?
Did you lubricate both the seal and the inside of the cylinder first with brake fluid?

Yeah I did and I actually got it to work but know when pressing the rear brake I'm not getting any firmness back, meaNing when I press the pedal I still can't brake

User avatar
Wilcoy02
Posts: 911
Joined: Sun Nov 21, 2010 11:37 pm
Location: Marengo, Ohio
Motorcycle: 1983 GL1100 I purchased 3/16

1983 GL1100I frame with an 80 engine. poor boy installed with C-5 ignition--DIED in Grande Prairie Alberta Canada 8/15


98 valkyrie sold 8/16

Re: How to rebuild your rear master cylinder

Post by Wilcoy02 » Tue May 31, 2016 8:54 pm

Justin

You are not alone on this point. The bike I am rescuing has the exact same problem. Rebuilt masters, new ss lines, rebuilt all the brakes, calipers. The front is fairly good but I am not satisfied with any of what I have done.

I've bled the lines with and with out a mighty vac and by hand so many times.

So when you find an answer PLEASE post it.

This bike had 2011 plates on it- so it sat a while.
Last edited by Wilcoy02 on Tue May 31, 2016 9:16 pm, edited 1 time in total.

Justinrobo54
Posts: 5
Joined: Mon May 30, 2016 2:02 pm
Location: Hemet california
Motorcycle: 1978 honda goldwing gl1000

Re: How to rebuild your rear master cylinder

Post by Justinrobo54 » Tue May 31, 2016 9:12 pm

Wilcoy02 wrote:Justin

You are not alone on this point. The bike I am rescuing has the exact same problem. Rebuilt masters, new ss lines, rebuilt all the brakes. The front is fairly good but I am not satisfied with any of what I have done.

I've bled the lines with and with out a mighty vac and by hand so many times.

So when you find an answer PLEASE post it.

Guess I'll keep messing with it til I get it but I'm thinking because it sat for so long it might be locked up calipers. So that's what I'm checking out next

User avatar
Wilcoy02
Posts: 911
Joined: Sun Nov 21, 2010 11:37 pm
Location: Marengo, Ohio
Motorcycle: 1983 GL1100 I purchased 3/16

1983 GL1100I frame with an 80 engine. poor boy installed with C-5 ignition--DIED in Grande Prairie Alberta Canada 8/15


98 valkyrie sold 8/16

Re: How to rebuild your rear master cylinder

Post by Wilcoy02 » Tue May 31, 2016 9:18 pm

I could not get one caliper to give up one of the pistons when I rebuilt. A wise old guy told me to take the end off the grease gun and pump the caliper full of grease. Well it worked slicker than snot.

Justinrobo54
Posts: 5
Joined: Mon May 30, 2016 2:02 pm
Location: Hemet california
Motorcycle: 1978 honda goldwing gl1000

Re: How to rebuild your rear master cylinder

Post by Justinrobo54 » Tue May 31, 2016 9:21 pm

Wilcoy02 wrote:I could not get one caliper to give up one of the pistons when I rebuilt. A wise old guy told me to take the end off the grease gun and pump the caliper full of grease. Well it worked slicker than snot.
I was thinking about doing that just boutique a grease gun a Lil while ago

Justinrobo54
Posts: 5
Joined: Mon May 30, 2016 2:02 pm
Location: Hemet california
Motorcycle: 1978 honda goldwing gl1000

Re: How to rebuild your rear master cylinder

Post by Justinrobo54 » Tue May 31, 2016 9:23 pm

Justinrobo54 wrote:
Wilcoy02 wrote:I could not get one caliper to give up one of the pistons when I rebuilt. A wise old guy told me to take the end off the grease gun and pump the caliper full of grease. Well it worked slicker than snot.
I was thinking about doing that just boutique a grease gun a Lil while ago

Bought*

bobbybiscuit
Posts: 139
Joined: Fri Feb 28, 2014 3:27 pm
Location: Plymouth, England, United Kingdom
Motorcycle: 1982 GL1100A Aspencade
Contact:

Re: How to rebuild your rear master cylinder

Post by bobbybiscuit » Sat Sep 03, 2016 4:51 am

I am making progress in getting my gl1100a 1982 aspencade on the road. New front brake lines installed (stainless lines) - bled and working as they should - also fitted new front brake master cylinder.

Rear brake mastercylinder - seals had been replaced about 18 months ago - piston moves freely - in fact too freely really. I have unblocked the return hole - looking clear - in fact I sprayed light spray oil through the return hole and it shot through perfectly. BUT i am wondering whether it has affected the seals. I have also taken apart my rear brake caliper. Used an mini buffing pad to polish pistons and bores and the pistons slide nicely in and out (without the seals in place)and I am pleased with the results.

Installed new brake line and also new rubber connection from top up reservoir to mater cylinder with new clips to secure.

Bleeding is a nightmare - I just cant get any brake fluid to reach the rear caliper - or should I say from the rear bleed nipple - the brake fluid reservoir has not gone down at all apart from the initial drop in level when the fluid reached the rear master cylinder.

So by the looks of it the rear master cylinder seals may well be leaking oil past them ie softened too much by the spray oil.

Has anyone got any advice please.

Once this is fixed just need to adjust front headlight - screw in the adjust has rusted out - but once sorted I am ready for bike to be MOT tested and then "happy days" for as long as the weather stays fine.

My bike started first time a few days ago after standing for 9 months. I had put the additive in the tank which reduces the ethanol and protects the seals in the carbs.

bobbybiscuit
Posts: 139
Joined: Fri Feb 28, 2014 3:27 pm
Location: Plymouth, England, United Kingdom
Motorcycle: 1982 GL1100A Aspencade
Contact:

Re: How to rebuild your rear master cylinder

Post by bobbybiscuit » Sat Sep 03, 2016 6:05 am

Just to add I have tried a vacuum pump for over 10 minutes - still no difference. Nothing being pulled through and no difference in the level of break fluid. This has me stumped.

User avatar
Wilcoy02
Posts: 911
Joined: Sun Nov 21, 2010 11:37 pm
Location: Marengo, Ohio
Motorcycle: 1983 GL1100 I purchased 3/16

1983 GL1100I frame with an 80 engine. poor boy installed with C-5 ignition--DIED in Grande Prairie Alberta Canada 8/15


98 valkyrie sold 8/16

Re: How to rebuild your rear master cylinder

Post by Wilcoy02 » Sat Sep 03, 2016 12:37 pm

I had same problem. I took an air hose to the bleed nipple and tried to shoot air back to the master. The oem steel line was plugged.
I sprayed brake fluid thru the line till it shot all the way thru. Blew some more air thru the line. Filled the reservoir and used the mighty vac. Brakes now work.

bobbybiscuit
Posts: 139
Joined: Fri Feb 28, 2014 3:27 pm
Location: Plymouth, England, United Kingdom
Motorcycle: 1982 GL1100A Aspencade
Contact:

Re: How to rebuild your rear master cylinder

Post by bobbybiscuit » Sat Sep 03, 2016 3:04 pm

Never thought of it possibly being blocked. Will disconnect the line and start again please a clean out just in case. i did leave the line out one night by accident on the ground and some creepy crawlies may have thought it was their new home. lol. So its back to the drawing board.

bobbybiscuit
Posts: 139
Joined: Fri Feb 28, 2014 3:27 pm
Location: Plymouth, England, United Kingdom
Motorcycle: 1982 GL1100A Aspencade
Contact:

Re: How to rebuild your rear master cylinder

Post by bobbybiscuit » Sat Sep 03, 2016 3:10 pm

I have also purchased two kits for the rear master cylinder. One as a spare for this one and I am going to try and bring back in to service another one i have which i bought as seized and boy isnt it seized!



Post Reply