gravity bleeding

I have started bleeding them and air bubbles stopped coming out within 30 minutes. From what I've read this is indication that the air is out but when I tried the brakes they didn't do a great job. The level feels tight and I can't move the wheel by hand when the brakes are applied but they didn't stop the bike very well on a quick (slow) spin up and down my street. I can keep bleeding and bleeding but I feel like I'm just pumping good clean brake fluid through and wasting it.

I know everyone says "just buy a MityVac or it will take hours and hours and hours to bleed your brakes" but how for-real is this? Is it really for real impossible to bleed without a vacuum bleeder? Nobody around here (Guelph, Ontario) stocks them that I can find and I don't want to wait for one from Chacal.

Some questions:
Does the lid need to be on the mc reservoir while I'm bleeding?

Does pressure build up within the MC reservoir? I.e. if the lid is not on tightly will that cause weak brakes (and prevent proper bleeding)?

 

there's a thread on here that describes how to bleed the brakes w.o a mityVac... try a search. basically, you unscrew the bleeder valve before you squeeze the brake lever, and then, with the lever held down, you close the bleeder valve before releasing the lever. rinse and repeat.

 

The MightyVac is Time and Labor Saving Tool.
There's NO reason you can't Bleed the Master Cylinder without one.

Test the Master Cylinder.
You can't Bleed the System if the Master Cylinder is the weak link.
Make a Test Fitting.
Pull the Bango Bolt out of the Brake Line at the Caliper.
Seal the Brake Line with some Hardware.
A Bolt, 2 Flat Washers, a nut, ... and some Rubber cut from an Inner Tube.
Put Rubber Seals inside the Flat Washers and seal the Brake Line.

Get an assistant.
Keep the Master Cylinder OPEN
Add Fluid to 3/4 Full.
Pump Brake Lever and see if the Master will develop Hydraulic Pressure.
Hold Lever tight to Handlebars.
Open Sealed Brake Line ... Bleed air.
Reseal.
Pump Brake Lever and feel for Hydraulic Pressure to INCREASE and RESISTANCE to Pulling Lever toward Handlebars to Increase.
Observe Master Cylinder during Test.

If Fluid shoots-up like Old Faithful ... Master Cylinder needs New Seals.
If Pressure is good and Brake Lever gets FIRM and Tight ... Master is GOOD.
Switch Lines to Caliper.

With Brake Line Hooked-up to Caliper ... Pump Bleed System.
Punp Lever 6 times. Hold firm. Open Bleeder. Ler Fluid or Air escape.
Brake Lever will collapse to handlebar,
Hold Lever firm to handlebar.
Close Bleeder.
Pump Lever.
Repeat until Master forced Brake Fluid through System.

Wrapping Bleed Nipple in Teflon Tape and poking a hole through the tape over the Nipple Opening helps.

 

no

no, but be careful fluid tends to squirt up and out sometimes
if theres a level or high spot in the line someplace a bubble will get trapped there, follow your lines up and see that a bubble has a clear path to go up
you might have to turn the wheel or tape the line to something
let it set overnight then wiggle the lever and see what you get
some people say tape the lever back over night
remember bubbles can't go down

 

I just changed over my brake lines last night on my XJ750 (long story....) and used my trusty syringe to re-fill the system from dry. Took about 20 minutes all up and only "wasted" about a syringe full of fluid (20cc) :wink:

I need to do a pic write-up of this method....maybe this weekend.....

 

i saw those big syringes at a Tractor Supply store if anyone is looking
Ouch !

 

I dont know if this is done but I bleed my m/c brakes by attaching a long tube and sucking the fluid out till no bubbles.

 

Generally, gravity bleeding works if you have the patience. Works for changing out the fluid but may not get rid of air bubbles. For that you'll have to pump (and possibly tap) or push new fluid up from below (the syringe method).