Gravity Bleeding: How?

[mreid]

Originally Posted by BK911

Here's another alternative:

<$5 pressure bleeder



I have used it MANY times on MANY cars with no issues.
The procedure changed slightly. Can bleed brakes in about an hour.
I set the regulator so it just barely pushes air out the hose.
Kinda gravity plus bleeding.

This! Four calipers done in about 15 minutes. No bench bleeding. No pumping. No hassles.

[911pcars]

With a completely drained system, about 16 oz (typically, 1 can) is all it takes to fill and gravity bleed - minimal waste. With pressure bleeding, some have run through several pints of sometimes expensive fluid to rid the system of air.

Brake bleeding

Sherwood

[Bob Kontak]

Originally Posted by porschenut

Bob, as you can see from my post, I was quoting your description of using the brake pedal method with the speed bleeders. THAT is what I'm talking about. I'm not talking about gravity bleeding.

This must have been a senior moment because I did not see your post. I see where you talk of pumping the pedal so my mistake.

Could have been the beer, maybe?

[piggdekk]

Just tried gravity bleedding in my 71 T with front S calipers, gravity bleeding seems to work fine with the rear calipers, but with the front ones when I loose the bleeders (I know is 2 on each caliper) I don't get any flow out of them until I start pressing the brake pedal. After some bleeding done by pushing on the brake pedal the feel is not too bad, but I cannot understand why gravity works on the rear calipers but not on the front ones. Any clues?
luca

[boyt911sc]

Originally Posted by mreid

This! Four calipers done in about 15 minutes. No bench bleeding. No pumping. No hassles.

With an air pressure regulator, use 10 - 15 psi. compressed air to bleed the brake lines and you'll be done in minutes. Probably about 5 mins. or less per wheel.

Tony

[911pcars]

Originally Posted by piggdekk

Just tried gravity bleedding in my 71 T with front S calipers, gravity bleeding seems to work fine with the rear calipers, but with the front ones when I loose the bleeders (I know is 2 on each caliper) I don't get any flow out of them until I start pressing the brake pedal. After some bleeding done by pushing on the brake pedal the feel is not too bad, but I cannot understand why gravity works on the rear calipers but not on the front ones. Any clues?
luca

With the bleed screw open, there's no normal impediment to the free flow of gravity-induced fluid flow from the reservoir>master cylinder>brake line>caliper. If the front calipers need some urging with the brake pedal, I might suspect one or more flex brake lines or some random debris might be the reason (but both calipers?). With advanced age, flex hose internals can deteriorate and expand which narrows the fluid passage. In extreme cases, it can block the return flow and cause the pads to remain extended onto the rotor.

MHO,
Sherwood

[piggdekk]

Thanks Sherwood,
I'm puzzled too. I should have mentioned that I bled the brakes after changing pads and putting new goodridge braided lines on the front calipers. the rear one are still the original ones as I was too afraid of damaging the hard lines and I need the car for the weekend. The brakes do bite a lot better, but the pedal still has a long stroke (as long as before I changed the lines and the pads). I wonder if air in the master cylinder would explain this. I believe the master cylinder is "dual" so front and rear calipers are somehow independent.
thanks
luca

[Brian 162]

Originally Posted by BK911

Here's another alternative:

<$5 pressure bleeder



I have used it MANY times on MANY cars with no issues.
The procedure changed slightly. Can bleed brakes in about an hour.
I set the regulator so it just barely pushes air out the hose.
Kinda gravity plus bleeding.

That is brilliant.
I'm going to try the same thing this week but I'm going to use nitrogen to force the fluid.