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Air in the brake line?

Entoptic

Entoptic

Red Power!
Joined
Mar 13, 2007
Location
Buy GoPro Now!
Moto(s)
MV Agusta Brutale Dragster RR
My front brake is very squishy. I literally have to grab a fist full of brake to see anything really happen. It does brake but not like I believe it should and I was wondering if there is a way to bleed the air out of the brake without any special brake bleeding tools.

Thanks in advance.
 
Without using a fancy vacuum pump, you're pretty limited to a rubber tube and lots of practice/patience.

Someone feel free to correct me if I'm wrong :angel
 
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If it started happening without disturbing the lines/bleeders/etc it is more likely that you need to rebuild the master cylinder. If you have a leaking caliper it will show up on the front wheel. Loss of feel at the lever with no leaks is usually an indication of failing master cylinder seals. They are little pieces of rubber and they wear out.
 
First, I sure hope you're not riding the bike.

If this just happened (you haven't done any brake work and haven't bleed/flushed the fluid), I'd look for two possibilities. 1. Your brake fluid is low and you pumped air into the lines from the master cylinder or 2. You have a brake line that is failing. Squeeze your lever and while doing so, check the lines for any bulging. A friend to help with the lever squeezing is handy.

If you have just worked on the brakes and flushed/bled the fluid, then you've likely just failed to get all the air out of the system. And yes, it's generally easy to do without fancy equipment. All it take is the right technique.
 
use a flare wrench. the bleed valves are really soft thus rounded off easily. pb blaster etc applied before trying to open them is not a bad idea if it's been a while
 
auntiebling said:
use a flare wrench. the bleed valves are really soft thus rounded off easily. pb blaster etc applied before trying to open them is not a bad idea if it's been a while
Click to expand...

I personally have seen flare wrenches do more damage than a standard wrench. And I spent a number of years wrenching. Problem with a flare wrench is they tend to open up when any torque is applied to them, rounding off the corners of whatever it is your loosening. If you are that worried about it, go get a 6pt box end wrench.
 
To the OP... I have the vacuum pump, and never use it. Search around at your local pharmacy for the 10cc plastic syringes. Attach them to a length of clear tubing. It works great as a vacuum source, and provides much better control of the bleed process.

FWIW, I follow up every vacuum bleed with an old school pump bleed. Seems to work best that way.
 
BTW... The sign of air in the lines is that there's a lot of play, and it gets worse as the system heats up and the air expands. If your brakes are mushy, but consistantly mushy, check your brake lever adjustment and your pad material - both an improperly adjusted lever and worn out pads can make it feel like there's some air in the system.
 
ST Guy said:
it's generally easy to do without fancy equipment. All it take is the right technique.
Click to expand...

Tap Plastics is your friend for some clear plastic tubing. You're welcome to borrow my non-fancy equipment (tubing into plastic water bottle) when you start looking into the problem. I live near the Panhandle.
 
msethhunter said:
I personally have seen flare wrenches do more damage than a standard wrench. And I spent a number of years wrenching. Problem with a flare wrench is they tend to open up when any torque is applied to them, rounding off the corners of whatever it is your loosening. If you are that worried about it, go get a 6pt box end wrench.
Click to expand...

Sounds like a chain store wrench.
 
OK... NO one actually said anything about: NOT over squeezing the lever! IF air is present the increase in press. will Always result in super small air bubbles that are almost impossible to bleed out! Be gentle, SLOWLY press the lever, also to expedite bleeding, lightly "rap" on the assorted parts{ calipers, mastercyl. junctions and hard lines} with a soft wooden dowel. broom handle, padded hammer handle ect. !!! most braking systems are designed to bleed normally, some are NOT!!! They inherently have pockets that will readily trap air! or moisture!!! Brake bleeding is Not a beginners sport!!! BEWARE folks cus "everyone want's to be a mechanic!"
 
Really? Brake bleeding is one of the simplest tasks that I can think of on a bike. If you can't figure it out then you're probably not fit to even ride one.
 
Burning1 said:
To the OP... I have the vacuum pump, and never use it. Search around at your local pharmacy, or feed store for the 10cc plastic syringes. Attach them to a length of clear tubing. It works great as a vacuum source, and provides much better control of the bleed process.

FWIW, I follow up every vacuum bleed with an old school pump bleed. Seems to work best that way.
Click to expand...

Fixed.

But wait! You're in the middle of A City! You don't have a feed store! What to do?

Hit up your local vet. S/he may look at you oddly, but they're usually receptive as long as you don't look like a druggie. (Remember to shave before you go in and ask. :teeth )
 
Basic hydro-brake laws...

If you lose pressure and cannot pump it back, check your Master.

If you lose pressure and CAN pump it back up, look for air.
 
Brake bleeding is not difficult. Bleed the system and see if things improve. If your brakes start working better and stay better then the problem is solved. If the problem comes back then look further.
 
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