Brake bleeding.

[The_heartbreak_kid]

I dont know how this is possible but I have never had to bleed my brakes before...but I think the time has finally come.

The inflexible metal tube brake line on my bike is bent. And needs to be replaced. Im assuming that the brake lines are going to need to be bled as well right? Or because it is below the MC do I still need to do it?

Im planning on following the process in my manual...but is there anything else i should I know? If I do it wrong will I know immediately or is there a possibility of it working at first then cutting out while Im riding?

 

[bobber bill]

It helps to wiggle the lines while bleeding. This will encourage trapped air to travel up and out through the reservoir. Also, lightly tapping the caliper all around with a rubber mallet will help evacuate any bubbles. Just watch for the bubbles to go away and tighten all your bleeder screws. Pump your master cylinder repeatedly until it firms up to your liking.

If you do it right, you will know because your brake lever will have good pressure/resistance. If you get it right once, it will remain that way. Speed bleeders help too.

 

[xander18]

I've found that bleeding brakes on this bike is far easier than on my 72 Duster (full manual drum brakes, yeeehaw). If you're doing it on your own look into buying a tool for it (these are all you need). If you're hesitant you can always just buy more brake fluid than you think you'll need and do a really thorough job at it.

 

[gggGary]

Assume no one has ever done the brakes and plan on doing a full overhaul. If the master cylinder is full of crap (nearly always) bleeding will be nearly impossible and drive you up the wall. Not to mention depending on a 30 year old brake system full of glop and rust isn't the smart choice. Hint before opening the system remove the caliper and use the master to move both pistons in the caliper, they can be very hard to get out once the system is open. From the hard brake line reference I am guessing you have a 72-76 bike.
LilBill has an excellent how to overhaul article to help you.

 

[retiredgentleman]

When I install a new brake line, I always prefill the line with brake fluid. I use a syringe to force brake fluid into the line, then install the line. The M/C are not designed to pump any volume, just pressure.