[rhenthar]

If you use a vacuum bleeder, especially the air-powered kind, it'll suck so hard from any point in the system, it will actually draw the pistons in on both sides. This means if you use the ABS bleed point, it's pulling fluid FROM the calipers, instead of through them.

Here is the key: Hold the brake lever fully while doing this. It cuts off the supply to the reservoir, meaning 100% of the suction is useful. The fluid level will not fall so long as the lever is all the way in, so you can just let your bleeder go to town drawing in all the fluid from the calipers and retracting the pistons fully. You will have to pump the lever slowly after all this is done, to extend the pistons back out. Figure 6-8 pumps, so you'll be adding fluid constantly at that point.

Repeat that a few times, and you'll get every last bit of air out.

Some air will come in around the threads in the bleeder if you're doing this on the caliper bleeders, and for this reason afterwards I do a few traditional bleeds: squeeze lever and hold - loosen/spray brake fluid out a hose on the bleeder - tighten bleeder - let go of lever. The ABS bleeder has an O ring that stops this effect and keeps the bleeder sealed despite it being loose.

Some of that is mitigated if you take the bleeder off and put some teflon pipe thread sealing tape around the threads, but make sure it's high enough up not to allow any loose tape to enter the brake system. I allow a couple of millimeters of bare metal to show at the bottom where you thread it into the caliper.

Remember in a state of lower pressure (suction) all air bubbles grow in size and generally move around more easily and faster.