Question about replacing brake lines and pads

[mercm3]

I am literally in the middle of swapping out brake lines and pads. When i drained the front lines using the mighty vac I noticed lots and lots of air bubbles, I didn't care much since i was just draining the system but I'm worried I might not be able fill and bleed the system correctly, what am I doing wrong? I included a picture showing my hose connection to the bleeder valve just in case my connection is wrong somehow. Any advice is appreciated since my lines are all over my garage at this time hehe

 

[Wavex]

hmmm, you're trying to bleed your brakes without the brake lines on?

That won't work bro hehehehehe bleeding should be done after everything is back together... think about it, you're trying to get air bubbles out of the closed loop system...

 

[Fred]

You'll get some bubbles with a mity-vac because it's constantly sucking air in past the threads on the bleeder nipple.

You'll have to go by feel instead of sight to get the brakes bled.

I'd finish up the job by bleeding manually to get the last of the air out. I've tried mighty-vac's, pressure bleeders, speedbleeder valves, and Vacula, and nothing I've seen gets as good a bleed as a piece of plastic hose and an 8mm wrench.

 

[Fred]

hmmm, you're trying to bleed your brakes without the brake lines on?

I'd been about to comment on that, but I figured that he sucked the fluid out, then removed the lines, and then took the picture.

At least I hope so. If you're right, then I'm afraid for his safety.

Fred

 

[Wavex]

It's either that or he forgot to keep the master cylinder reservoir topped off

Having another set of hands helps to bleed brakes... one guy with the pump and 8mm socket taking care of the caliper, the other on top filling the reservoir as you suck fluid out from the bottom...

The guy on top can help finish the job manually by "pumping" the lever while you open/close the caliper nipple...

 

[mercm3]

yeah drained the system then pulled the lines off then I started worrying about all air i saw when i first started draining and decided to snap the pic

 

[Wavex]

ok, I am even more confused now.

Do you have the new pads and lines mounted on the bike? Yes or no.

If you don't, do it. If you do, and are still seeing a lot of bubbles after filling your brake reservoir and pumping for a few minutes, you may have an issue with your pump or that caliper's line...

If you could be a bit more specific that would help.

 

[C-bus Biker]

Speaking of brakes.... is the brake light supposed to have some play or is mine loose?

 

[mercm3]

so I installed my new lines and new pads, the rear lines were a breeze and were bled very easy. Somehow I can't seem to bleed the fronts, my steps are

first I tried the mityvac
I connected line to bleeder valve
pumped the pump to create vaccuum
open bleeder valve, crazy mass bubbles
pump like all sorts of fluid down full of bubbles

so I decide to use the old fashion method
I open the bleeder
my wife pulls the brake,
I close the bleeder
my wife releases brake
then pumps brake
we do this for about 30 mins nada no tension at all

I was curious if I finish 1 side on the front will the brake lever have any tension?
Also how long does it normally take to bleed a side?

 

[huxy]

I open the bleeder
my wife pulls the brake,
I close the bleeder
my wife releases brake
then pumps brake
we do this for about 30 mins nada no tension at all

I think you're opening the bleeder at the wrong time in the sequence. You pump the brake, hold the lever to the bar, then open the bleeder and fluid/air comes out. Then close the bleeder and repump. Make sure the level of fluid in the master cylinder doesn't drop too low or you end up letting air back in at the top.

It took me and a mate probably 20-30 mins of pumping the lever and bleeding to get pressure in the system. We did stop for a drink of tea and a biscuit or 10 to keep our strength up though

When it is all done, leave it for a couple of hours (or overnight), and then see if any more bubbles come out.

The back one came up much quicker but the hose is much shorter so I guess less air can hide in there.

 

[Unseen]

Speaking of brakes.... is the brake light supposed to have some play or is mine loose?

It supposed to have some play :thumbup:

 

[Fred]

The problem you're having now is that you've got a master cylinder full of air. It's like a pump that has lost its prime. Until you glet fluid into the master cylinder, you won't be able to bleed the brakes all that well.

Here's something I wrote a while back. If you follow the third step's instructions, you'll be bleeding air out of the master cylinder.

ratbike.org: Tips for Easy Brake Bleeding

 

[mercm3]

well finally brakes are bled and everything is all good!!!!!... sorta there was some collateral damage last night when I guess "I forget"(hmm did I really?) to let my wife know how dangerous the brake fluid was, part of my brake master cylinder got paint damaged, anyone know where I could get some paint to fix this?(sorry for the crappy pic)