K11 Owners Group

blackcash · Posted: Sat Apr 30, 2011 4:39 pm Post subject: Brake Bleeding 101

I started the other day to circulate new fluid into my front calipers and got what seems to me all the air out the system, and new clear fluid going through but the brakes will not work .
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Ernie-NH · Posted: Sat Apr 30, 2011 7:15 pm Post subject:

Hi BlackCash...

First: gotta know how they functioned before you began,, what you did step by step,, and what ( other than they dont work ) are the symptoms now?? ( leakage, lever feel, etc... )

OK....??

Regards...........// Ernie in NH
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blackcash · Posted: Sun May 01, 2011 1:39 am Post subject:

well im bringing the brick back to life i got it and the brakes were some what stuck like the calipers were engaged somewhat. so i bled some pressure just to free up the wheel so i could move it , i opened the bleeder screw and worked the pistons back in the caliper . there is no leakage no suction sound when i press the hand control. although it is spoongy . im working with a brake bleeding kit and fluid is working through i pushed the old dark fluid through and am getting clear but no caliper movement i can feel the caliper and disc pulsate when i squeez the brake lever though .
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87 k75 31,000 "Blackcash"

Ernie-NH · Posted: Sun May 01, 2011 11:46 am Post subject:

Good morning BC...

How long has this bike been idle ?? Sounds like brakes have not functioned in a long time. If so, its unlikely that you can simply attempt to replace the fluid and expect a normal function. I would suggest that you imply start from scratch, and that includes rebuilding the front master cylinder as well as disassembling the calipers and refitting them with new seals, new dust seals, and re-polishing the piston surfaces themselves to remove residue from decomposed brake fluid. A simple re-bleed will NOT leave you with a dependable braking system !! If you dont have one already, get a copy of either Clymer or Haynes as a guide and let us know how you make out. Another valuable resource for diagrams is Max Motorcycle online, to find and buy the parts you will need to repair your brakes.

Good luck............// Ernie in NH
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blackcash · Posted: Sun May 01, 2011 12:54 pm Post subject:

yeah it sat unused for a lil over a year and i was figuring i would have to over haul the calipers im strapped in the wallet at the moment but i plan on buying the kit in the near future

BobZ(IL) · Posted: Sun May 01, 2011 10:09 pm Post subject:

I suggest you remove the calipers, take the pads out and clean things up. Spray brake cleaner on the piston surfaces, move them in and out to ensure they are not frozen, then reassemble.

Unless pistons are not moving, I'd not rebuild calipers until all else failed; such as replacing brake lines, looking into the master cylinder, etc.
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Ernie-NH · Posted: Mon May 02, 2011 10:33 am Post subject:

Good morning guys...

In the first post from "BC" he noted that the "brakes are not working" and since he moved the bike, we can make a guess that the pistons are retracted and perhaps 'frozen' in place. Secondly he mentioned that the brake lever action feels "spongy"... if the pistons are frozen in the retract position, the spongy feel means that fluid is forcing itself past one or both of the cup seals in the Master Cyl. assembly. These cup seals are inexpensive and can be assembled safely to the plunger using dental floss to stretch them over the plunger piston itself. ( ie: a cheap fix )

If the pistons are 'frozen' in place however, one reason could be that the piston seals are now adhering to the caliper wall due to rubber degradation. Clean and replace seals will take care of that ! ( ie: also an inexpensive fix )

When glycol-base brake fluids degrade ( water in lines ) they form several complex acids which all cause the rubber to revert and form a 'gluey' substance which eventually hardens in place as it ages. In addition, these acids will attack the metal wall of the caliper over time, forming a residue there as well, and over a longer period, will actually pit the wall itself. ( ie: expensive fix @ $450+ per caliper )

While "BC" may get some of the caliper action to return with a simple cleaning, for sure all of the rubber elements in the brake system are by now degraded due to chemistry and a lack of use during the long period it was idle. I for one would feel far more confident having a braking system I KNEW to be good, rather than one that may be compromised. After all, "how much is one's life worth, when facing an impending collision ??"... it must certainly be more than the cost of a simple clean and rebuild ??

Just my $0.02......

Good luck BC...........// Ernie in NH
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blackcash · Posted: Mon May 02, 2011 1:42 pm Post subject:

Look im just now figuring out alot about motorcycles in general I know my fair share of auto but thank god I found this site because everyone so far has been a big help im gonna pull my calipers apart and look into the resivor and go about it like that at first due to lack of cash . I do have a haynes on the bike is the clymer any better should i get one ?

Ernie-NH · Posted: Mon May 02, 2011 7:49 pm Post subject:

Hi BC....

No problem! However when you disassemble and remove the pistons, be very CAREFUL of the piston seal itself as well as the outer "dust seal" ( ie; the one with the conical lip ) these are "rubber" parts and have been permeated with brake fluid ( as they are supposed to do ) and have very fragile contact surfaces. Any rubbing or contact cleaning, may render them useless. Run them each under warm water, check each for chips and/breaks, and then soak them in clean brake fluid for a day before reinstalling IF they are still useable. Also, clean the inside of the caliper walls, ( ie the portion that the piston rides in ) using a soft cloth wet with warm water and dish washing detergent, then use the brake cleaner to remove all of the embedded residue. Lube the caliper walls after that with clean brake fluid and reassemble. Once you've got everything back together, and bled, you'll quickly know whether you have been successful or not.

As for the manuals,,, both Clymer and Haynes are handy, BUT the authorative source is free using the K11OG resources at:

<<< http://k11og.org/forum/viewtopic.php?t=4715 >>>

Good luck and keep us posted !!...............// Ernie in NH
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