Gravity bleeding Options

[930cabman]

Everyone knows how easy (?) bleeding our brakes are, I have tried the friend method, shooting 5 or 10 psi through the MC and gravity method. From what I have seen all have a similar level of success. Prior to replacing a rear caliper the pedal was solid, since the new caliper I can get about 80%.

This old horse must be well beaten by now

[technicalninja]

adjusting free play comes to mind as the most common reason for lower pedal.

On the bleeding process itself:
I've been using a vacuum bleeder system for decades and it has not failed me once on any brand of car.

https://www.amazon.com/FOUR-UNCLES-Bleeder-...985039&th=1

I just have the 2l vacuum chamber. The re-fill bottle does not exist in my shop.

I found a small orifice taper end adaptor that fits in the bleeder hole after I remove the bleeder.
That unit can suck a master cylinder dry in seconds without some form of restrictor.

Mine has a tiny hole in it and it gives you plenty of time to keep the reservoir filled.

I use it to flush old brake fluid out of systems every week. The first one I had was a "Vacula" brand bought off a tool truck which was damn expensive. It lasted 20+ years.
Doing amazon searches I found the one I own and Amazon told me last time purchased was March 26 2018. It was far cheaper and has kicked ass for almost 5 years now on a weekly basis.
I have an automotive AC specialist shop and do other work all the time. Flushing brake hydraulics is a normal PM that I suggest at least every 4 years (daily driver appliance cars).
This is my current unit

https://www.amazon.com/Capri-Tools-Vacuum-B...la-568857234602


My adaptor (which is critical for this to work) is sort of like the pointed adaptors in this kit .
https://www.amazon.com/MV8000-Automotive-Tu...la-316724733774

My process is as follows:
Suck master reservoir dry with tool. If easy remove reservoir and clean with water in sink. Dry it like you mean it and then rinse it out with alcohol. Dry it like you mean it and I will normally bake it in the sun for 20 min if possible. Wipe out recesses that reservoir fits into (not possible with Porsche).
re-install and fill with your brand of brake fluid. I normally use DOT 4 but I NEVER use DOT 5 silicone fluid. Dot 5.1 is OK to use as well.
Go to farthest bleeder from master. Break bleeder loos with 1/4" socket and apply vacuum into bleeder orifice. Unscrew bleeder from caliper, switch vacuum tip to caliper. If it fits right, you will get NO bubbles in the stream coming out and you can see this through the clear tubing. Pull fluid till the color changes and stick bleeder back into caliper. Move vacuum tip back into bleeder orifice. Screw in bleeder and lock lightly with wrench.
Lather/rinse/repeat with the other three calipers. Never let the master reservoir go dry.

After the suck portion is done, I will remove adaptor from vacuum line and place line over each bleeder itself. Bleed caliper normally while using line to catch brake fluid (no vacuum applied here).
I NEVER allow the brake pedal to go farther than normal used stroke into the master cylinder bore. The unused lower section of the bore can trash the umbrella seals on the master piston if it's stroked into the floorboards sometimes.

I'll do the normal bleed and then final tighten the bleeder with the socket. After everything is done, I'll blow the bleeder out with shop air and re-install the bleeder cap with a little bit of silicon grease. This will stop any corrosion that locks bleeders into calipers.

I'm now stupid careful with brake fluid as it's hydroscopic and because of that is easily absorbed through the skin. It will process through the liver but not through the kidneys (or vice versa) and is cumulative in the human body. It never comes back out and can cause trouble much later in life.
I worry about this as I've been drenched in brake fluid many times over my automotive career and may have already killed myself with this crap...

[rhodyguy]

Get speed bleeders and and clear plastic tubing that fits them. Enough tubing to reach from the pass side caliper to the floor next to the drivers door.

[VaccaRabite]

There are three things that happen:

1) air gets bound up in the proportioning valve
2) Some calipers have 2 bleeders, and you only bleed the highest one.
3) You let the master cylinder go dry letting new air into the system.

I use a motive power bleeder to help prevent #3.

I have also used the "Long tubes" method with speed bleeders. You use a LONG clear tube - long enough to run from the rear pass bleeder back to the reservoir. Pump till you can no longer see bubbles in the line. The res never goes dry as you are always pumping fluid back into it. When one caliper is done, move the tube to the next. Back brakes first then fronts.

Either method will get my brakes hard as a rock in very little time.

In my experience, you have to choose between a Motive bleeder or speed bleeders. The motive does not have enough pressure to overcome the ball valve in the speed bleeders. But, it does keep the res full, so its still useful.

Zach

[rjames]

Get speed bleeders and and clear plastic tubing that fits them. Enough tubing to reach from the pass side caliper to the floor next to the drivers door.

This.

Tried everything else and was getting nowhere. Speed bleeders and enough tubing so I could watch the bubbles disappear while pumping the brakes made short work of it.

[930cabman]

Sounds as though the Speed Bleeders have it, thanks all for your input

[rhodyguy]

With SBs, you don’t have to go through brake bleeding 101 with the helper. Usually the wife in the past.