best way i've found..when it comes to bleeding brakes..spec if you have taken the system apart..after it 's all back together..take a pair of vise grips..clamp them on the rubber sheath that wraps around the line..about 3 or 4 inches from the master cylinder..pump the master cylinder up..until you start to fill pressure..then while holding the lever in..release the vise grips..this forces fluid down the lines..reclamp the vise grips..pump the handle up..rinse and repeat..in no time at all.you will force the air down to your brake cylinders...do not open the brake bleeding screws while doing this.
I'd be afraid of damaging the hoses, and I wouldn't even consider it on stainless braided lines. The part that confuses me about this method is 1) why are you only 3-4 inches from the master cylinder? There is a lot of line between there and the slave/caliper. 2) How do you get the air out without opening the bleeder screws?
Gravity bleeding works pretty good too. Just don't let the reservoir get low.
It does, but it also takes a while.
One more method that works great, I guess it's pretty much the same as the pop bottle method, but can use a lot of brake fluid:
1. Get a couple feet of clear tubing, ID should be the same as your bleeder screw nipple (tight fitting).
2. Put one end of the tubing over the nipple. If the tubing is the right size, this will take a bit of force. The object is to get a good seal between the tubing and the nipple...I've used a small zip tie around the tubing to add a little extra assurance.
3. Get a large CLEAN glass jar...pickle jar, quart jar, etc. Set it on the ground below your bleeder screw. Cut the tubing long enough so the end of it sits in the BOTTOM of the jar.
4. Pour a couple inches of brake fluid into the jar.
5. Fill the reservoir.
6. Crack the bleeder screw...just enough that when you squeeze the lever you see air bubbling into the jar of fluid, or you see brake fluid being forced into the tubing.
7. Pump the brakes while monitoring the fluid levels in the jar and reservoir.
8. Continue this process until you no longer see air in the tubing / bubbling up in the jar.
Important: DO NOT let the reservoir run dry...you'll just pump air into the system and have to start over. If the jar fills with fluid, close the bleeder screw before removing the tubing from the jar. I personally don't reuse the fluid from the jar, I dump it out and continue with fresh fluid from a sealed container. You may have to do this for 5 minutes, let the air settle for 5 minutes, and so on...depending on the length of your lines and the amount of air in them.
What this does is forces air out into the jar of fluid, but instead of sucking air back in when you release the lever, it sucks fluid back in.
Brake fluid cab degrade many types of tubing, so throw it away when your done. I've always used vinyl tubing since it's available anywhere...but I never reuse it.