Need help with Master cylinders

[dschmitta]

Hey everyone,

Hit rear brakes yesterday and poof, nothing, brake was not nthere. Stopped, noticed trail of brown liquid, almost looked like mud!!! Adjusted rear pedal tight, pushed and fluid sprayed onto ground. Took apart and drained, fluid looked almost like mud. Couldn't believe it. Looks like the two horseshoe shaped metal clips just rusted into nothing. Also, decided to check front M/C fluid and it was black. Glad I found out before i had no brakes!.

QUESTION: I was going to use kit to fix rear M/C. Was just going to drain flush front and then use DOT 5 silicone in both. Heard the silicone doesn't break down and doesn't have moisture problems like DOT 3. Is this true and would kit work or should I just replace with new M/C assembly? Any help appreciated

P.S. Does anyone know where to get parts for bike. 1980 xs1100G. Microfiche was showing M/C assbly not available. Thanks

[greatnw]

MC rebuilds are easy and life saving IMHO. Really, as long as you can clean up the MC and the inside is nice and shiny the rebuild kit solves most trouble.
I'm with you on the synthetic fluids helping to drastically retard fluid deterioration. It is one of the first things I do on any vehicle I acquire.
I still have my XS11 apart for some other repairs but will be upgrading to steel lines on the front.
When I first went through my project I didn't think I had a chance of rebuilding them because everything looked really nasty when I took them apart. However, a little cleanup and new kits and they both work great.
Rebuild kits are under $30, MC's are three times that and really not usually necessary.
Glad you were able to stop! Brake failure can lead to heart failure!

[natemoen]

Rebuild kits are available and 9 out of 10 times that solves the problem with the master cylinders, most people can even get by with just cleaning and refusing the parts. What was leaking that caused the problem?

About dot 5. It is not that it stops water from getting in the system, it is just that the water does not mix with the fluid. Instead the water pools in the low points of the system. I would not switch to dot 5 unless I swapped out the lines as well. Either way ,dot 5, 4, or 3 regular fluid changes must be done to curb the water buildup in the fluid because it will get in no matter what!

Now my opinion. I personally would rather have the water dispersed throughout the fluid rather than a puddle in the bottom of the MC or the caliper. I do not see the added expense of dot 5 worth it, and I do brake fluid changes every year or two on my vehicles and never have any issues with the dot 3 I use.

[DGXSER]

Look for seller Georgefix on ebay for kits. I belive he carries the brake kits.

As to DOT 5, be VERY Careful!! DOT 5 does not work and play well with DOT 3 or 4 at ALL!!! If the two mix they tend to form a gelotinous goo sort of like pudding with air soft pellets mixed in. So if you plan to switch, make sure you thoroughly clean EVERYTHING including the lines, otherwise you will end up with worse looking gunk than you have now.

This should serve as a good reminder to everyone, check your brake fluid, if its been two years or more, or if it looks at all brown and nasty, flush new fluid into the system!!

[oldyam80sg]

Agreed-Have gotten myself into a habit to change fluid every 2 years.Fluid is inexpensive and i have found out speed bleeders are the best thing to have.Also many modern bikes use DOT 5 brake fluid-My 1999 Kawasaki ZRX 1100 uses it in there.If it doesn't say DOT 5 on the cap-don't use it.Also DOT 3 is available at many places-7 -Eleven,many convenience stores and food stores also carry it.

[fredintoon]

- - - I was going to use kit to fix rear M/C. Was just going to drain flush front and then use DOT 5 silicone in both. Heard the silicone doesn't break down and doesn't have moisture problems like DOT 3. Is this true and would kit work or should I just replace with new M/C assembly? - - -

Hi dschmitta,
us senior citizens remember our dads telling us horror stories about how combining vegetable-based engine oil with dino-based engine oil creates an engine-destroying anti-lubricant.
Same with mixing DOT3 or DOT4 with DOT5 in braking systems.
Either will work. DOT3 or 4 absorbs moisture to denigrate the fluid. DOT5 lets moisture gather in beads to rust steel internals. You takes yer choice. A combo turns to sludge.