• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Rear master cylinder rebuild

  • Thread starter Thread starter snyderman
  • Start date Start date
S

snyderman

Guest
One of the things that I can do on my project during the winter is rebuilding my rear brake master cylinder. It is all there, but the seals seem to be shot. I have not even taken it off the bike yet. I did a bit of searching and looked at Basscliff's site, but found nothing on rebuilding the rear master cylinder. Any help out there?

Thanks,
 
snyderman said:
One of the things that I can do on my project during the winter is rebuilding my rear brake master cylinder. It is all there, but the seals seem to be shot. I have not even taken it off the bike yet. I did a bit of searching and looked at Basscliff's site, but found nothing on rebuilding the rear master cylinder. Any help out there?

Thanks,
Click to expand...

It's pretty simple. Take it off the bike and tear it down. Clean everything and replace the rubbers with OEM, if you can get them. Push a strand of wire through the tiny breather hole in the main body - it almost certainly has crud in it. It's easily missed and the unit will not work properly if it's not clean.
Have confidence, you can do this easily.

Take digital photos as you go, makes it easy to remember how it goes back together!
 
Last edited:
Do a search on here and you'll find tons of threads about it. But basically Allojohn has it right.

Make sure you bleed everything properly.
 
Inspect the aluminum master bore for pitting. If corrosion has set in, the master can not be rebuilt.

IMG_1148.jpg


IMG_1149.jpg
 
If you don't have a two stone wheel cylinder hone, you can roll various grits of sandpaper up and hone it with that.

Daniel
 
Thanks for the info, I will have to see how bad it is when I tear into it!
 
I wouldn't bother to hone an aluminum GS master. Honing is good to clean up cast iron automotive master cylinders, but not aluminum masters. The GS master cylinder bore is highly polished from new and any abrasives you put inside only degrade the surface finish and reduce seal life.
 
Pessimism and "I have never done that" or "had any success with that myself", strikes again! :( :rolleyes:


It works and I have been doing it for over 35 years.


Daniel
 
7981GS said:
Pessimism and "I have never done that" or "had any success with that myself", strikes again! :( :rolleyes:


It works and I have been doing it for over 35 years.


Daniel
Click to expand...

The stock finish is something like Ra<8. This is a very smooth finish - equal to polishing with something like 600 grit sandpaper.

Putting a grinding hone inside an aluminum master cylinder bore will degrade this finish significantly and should be avoided. A rough finish will wear the rubber plunger pieces.

The only reason to hone a master cylinder is if there is contamination on the surface of the metal. When a aluminum GS master cylinder corrodes the damage goes down into the metal forming a pit. Sanding over the top of the pit does no good.

I don't care if someone has been doing something wrong for 35 years without consequence. Doing something wrong is doing something wrong.
 
Sorry to hear that some people just can't repair much of anything. :(
Just buy new OEM parts and be happy. ;)
After all, nothing works on these bikes but OEM, right? LMAO!!!

Daniel
 
Thanks for reminding me Daniel...

Original Suzuki brake system seals (master cylinder kits/seals, caliper seals/pistons) are WAY better quality than commonly available K&L parts. In many cases the OE parts are cheaper as well. Two times I wasted considerable time farting around with brake system problems only to eventually trace the issue to crappy K&L parts. Consider this an official warning.:p
 
To the OP, lets see what the factory has to say about the matter...

using a piece of wood or soft metal, push the internals out of the cylinder bore, taking care not to nick or scratch the bore wall
Click to expand...

and the service limits as stated in the GS1000 service manual...

bore standard 14.0mm (.551 in) service limit 14.05mm (.553 in)
Click to expand...

you can take that for what its worth.

to 7981GS, yes I have sanded 'many' a master cylinder/ wheel cylinder bore over the years. did I have 100% success at it? no. would I try sanding the bore on my own bike? sure, and I have. would I recommend else to polish out anything more than a 'light' pitting on there own equipment? no.
 
Nessism said:
Original Suzuki brake system seals (master cylinder kits/seals, caliper seals/pistons) are WAY better quality than commonly available K&L parts. In many cases the OE parts are cheaper as well.
Click to expand...

99% accurate. You can get better, stainless steel pistons (well we can anyway :p). Non OEM rubber isn't - it's jelly. It's junk.
 
I've Used K&L on all my bikes...Never had any of these "problems".....
You guys make it sound like the brakes will fail at 1,000 miles!

My advice to the OP...install what you can afford.
You want Good brakes...switch to stainless steel lines...THAT'S well worth the money!


I have the same bike as you, the Rear Master Cylinder is the EASY one, lol.
I think I have photos of the Tear-down for this bike.
 
Last edited:
You must log in or register to reply here.
Back
Top