After a lot of work and money...it's official--no front brake at all

[BigD_83]

Well, some brake pressure this morning, but if it follows its usual pattern it will gradually reduce. Exactly like the oem rebuilt MC--but perhaps a bit more lever travel at the highest pressure it builds.

Tempted to return to the OEM MC. At least I know the piston and cup set is new and it does give me a bit more brake pressure.

I checked the line when I had the system torn down. I blocked one end and applied a vacuum to the other end. It held the pressure with no leakdown.

Video uploading now. Will add link when it gets done.

As always, I really appreciate the time you have all taken to help figure this out.

Curious about something; what has the difference been in your daytime/nighttime temperatures?

Do you store the bike in a heated garage?

[oldrookie]

Yep, always in the garage.

I recommend that you all buy stock in brake fluid companies. I've increased their profit margins significantly since I started this process.

[oldrookie]

Nice term "violent bleeding"
I have always done mine that way in MCs and in other vehicles and it has always worked.

I get a buddy to pump the lever briskly then squeeze the lever all the way in.
Then I crack the bleeder to let the pressuirized liquid out.
Close the bleeder and have the buddy repeat the process till the air is gone.

Make sure the res is topped off and level and its should work.

Gotten to the point where I can do both tasks myself. No buddy needed. Unfortunately, it is having no effect.

[BigD_83]

Yep, always in the garage.

I recommend that you all buy stock in brake fluid companies. I've increased their profit margins significantly since I started this process.

The reason I ask about temperature fluctuation is that your description and video plays out like there is an air bubble trapped somewhere in the system, and should get a bit smaller when cold (i.e. better feel in the morning) and worse when warm. I have to admit that you are getting way more travel in that lever than I would expect from JUST a small trapped bubble.

I recall someone (DPep?) mentioning about getting a bubble inside part of the MC and experiencing something similar to what you have been going through.

[Agemax]

Yep, always in the garage.

I recommend that you all buy stock in brake fluid companies. I've increased their profit margins significantly since I started this process.

as long as you are bleeding into a clean container you can reuse that fluid to carry on bleeding until it is right. then once you are happy bleed again with new fluid to finish the job

[john82q]

I have to admit that you are getting way more travel in that lever than I would expect from JUST a small trapped bubble.

yes, but he's got but numerous small trapped bubbles...

[salty_monk]

Tom MLC had leaky bleeder valves that led to this problem... Try some PTFE tape on the threads. (No - he didn't see fluid leaking either & yes the bleed screws were brand new replacements).

Nessism & JC had something similar that turned out to be worn sliding pins in the calipers...

Just a couple of ideas for you in case getting violent with your bleeding doesn't work...

With the amount of brake changes, modifications etc etc I have played with the last few years I have bled my fair share or systems. I usually "suck" the hose at the caliper end (or put a vacuum tool on it) until I see fluid then bleed away as normal.
I have needed to cable tie the lever back to the bars for a couple of days on one or two occasions (leaving it like that under pressure seems to help the air bubbles travel up & out a lot).

Good luck

[oldrookie]

How do you know if the slider pins are at fault? Caliper appears to be moving more at the top than at the bottom.

Uploading a video showing the interior of the MC when pumping the brakes. Seems to be only one hole in the GS500 MC. Bubbles came out at first, not now. Doesn't appear to any air coming out the bleeder at this point either...just simply no brake lever pressure to speak of.

[oldrookie]

http://www.youtube.com/watch?v=hTAirCVx4Bs&feature=youtu.be

[chuck hahn]

You tell if the pins are at fault by removing them and wire wheeling all the craqp off them and then reinstalling them. roll them on something absolutely flat like a piece of glass to see if they are bent even the slightest bit also.

[chuck hahn]

Well the video clearly shows the holes arent plugged. You sure you have the front cup in there facing the right way?? The dished side should face the banjo bolt hole.

[oldrookie]

I did not tear this one down to inspect the piston and cup set. Sounds stupid as I write it. Waited a week for the part and got excited to see it would solve the problem.

Went to install it and found that the plastic window was shot and had to order the glass replacement online to fix it. Then I had to modify an old brake switch line to accept the new switch. Put the teardown aside and dealt with the obvious problems.

I'll pull the pins and inspect them again, but there were no obvious problems with either of them. The whole system was pretty clean for a 29-year old bike. Had just under a 10 thousand miles on it when I got and had been stored inside.

[john82q]

I dont see any activity in the fluid, like the return spurting back.
but maybe its too deep, usally if the fluid is low it will actually squirt/splash back.

Are you sure the mc is actually pumping?

[chuck hahn]

John....that mastr cylinder is off a 550, and what i saw in the video is thatbthere is no return port. You can see the piston moving in the pick up hole though.

[john82q]

Even so there still should be returning fluid...

oldrookie was the bleeder open when you shot this video? if so thats one reason why no return. And if so did it pump out a good amouint each stroke?
the level dosnt seem to drop much...


Btw I thought port less MC were a toyota/ABS thing...