Front brake advice please

[gwilki]

Well, Chief, since you asked so nicely, I am back to report on my embarrassment in this particular case.

Having spent hours on trying to get "lever" and failing, my excellent mechanic solved the problem in less than 30 minutes. All that was needed was some patience and a better understanding of where the air was trapped. He told me that, on these cylinders, it's best to tilt them in such a way as to cause any air to rise. Then do not pump the lever several times, as I had been taught. Simply lightly pull on the lever while releasing the banjo bolt. Patience and slow but sure is the solution.

All this said, I am back on the road again - well, as soon as it quits raining.

[chief]

Please be sure and let us know the outcome!  Cheers. 

[gwilki]

Thanks for this Chief. After some hours on this, I dropped off the bike at my mechanic.

I have the vacuum set up. I could draw fluid through the line. Before that I was able to suck air through it. I installed the new seals, but I'm thinking maybe they are not the correct ones of the master cylinder itself is bad. Even after pulling clear fluid using the vac, I had no "pedal" and no amount of pumping the lever would give me any.

At one point, I loosened the banjo at the master cylinder and pulled the lever - nothing.

I hope to hear some time this week what the mech found.

Thanks again.

Grant

[chief]

Have a look at your bleeding procedure, make sure you are doing it correctly. Verify the hoses are cleared of any debris. Verify seals. Make sure the hoses are installed properly and fittings are tight.

If you aren't seeing good fluid flow when bleeding you have hose/seal problems.

I use a mightyvac for bleeding...

https://www.vulcandrifterriders.com/mityvac.html

brake system maintenance.

[gwilki]

Back again, Chief. I got the kit today got the new seals on and the master cylinder back on the bike. I have been playing with this for a couple of hours and I cannot for the life of me get this thing to bleed.

Here is what I've done. I have vac bleeder so with the top off the cylinder, I drew a vacuum at the caliper and opened the bleeder. After a couple of tries, I got fluid in the container. I topped up the master cylinder and put the top back on. Then, I tried bleeding by pumping the lever and opening the bleeder valve. I could not get anything at all. The lever goes to the handle bar. The caliper is not moving at all.

When I had the master cylinder apart, I checked both of the holes in the bottom of the cylinder. The large one was easy to clean. I have jewellers drill bits, and I was able to confirm the tiny hole was clear using one of them.

Update: This morning, I loosened the banjo bolt at the caliper and pulled the brake lever. Nothing came out.

I am at my wit's end. Any thoughts, PLEASE.

[gwilki]

Thanks much, Chief. I found a local source who can order the kit, priced at only ~$32. It should be here by the end of the week. I'll close this with a report on how I make out.

[chief]

First, triple check everything. I'd go ahead and replace the seals... they are supposed to be evaluated and replaced every 4 years. Also make sure all the passages and ports in the master and  caliper pins and bushings are thoroughly cleaned. Could be a debris problem. If one of the ports/pin holes in the master is clogged you will have problems. 

[gwilki]

Last Fall, I replaced the brake line, brake pads and new fluid. At the start of this riding season, all was well.

Two days ago, I noticed that the lever was almost touching the grip to get the brakes to engage. The master cylinder was full. I bled the brakes again and got a bit of improvement, but not enough. I stopped work for the day. Today, I pulled the lever and nothing. Master cylinder is full.

I suspect that the seals/piston, being 22 years old, are not holding pressure in the system.

There is a rebuild kit available here in Canada for ~ $55.

Given the symptoms and what I've done so far, can someone here please tell me if you believe that I am on the right track believing the master cylinder needs a re-build?

thank you