'67 MASTER BRAKE CYLINDER BLEEDING

[Rob A.]

I let the rear half of my master cylinder run dry while vacuum bleeding the rear calipers. I refilled it, but can't get any fluid out of the rear bleeder valves depressing the brake pedal now. Assuming this is from letting it run dry, can I resolve this without disconnecting any lines from the master cylinder?

[Joe R.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Rob,

Patience is the key here to get a firm pedal. Fill the MC, open the valve on the right rear and go and have breakfast. I slip on a clear plastic line and put the end in a cup or can. Check on the MC and keep it full this time. Do the same for the left rear. It won't take as long so keep an eye on the left rear. Don't eat too many wheaties.

Regards,

JR

[Jack H.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Suggests you've got a LOT of air in the rear lines to bleed out. You might want to consider buying/using a Mityvac hand pump ($30 list, autoparts stores + Eastwood catalog) to make the bleeding a 1-man job by 'sucking' fluid through the lines from the rear wheels vs. pushing it through via the brake pedal....

[Jeff A.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Rob,

ANother handy item are the anti-siphon bleeder valves for the calipers. They don't let the air come back in when you use the Mighty Vac and really speed the job up.

[Rob A.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Where can I find the anti-siphon bleeder valves?

[David Z.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Vette Brakes has them as do other vendors. Search for "Speed Bleeders"

Here is an example:
http://www.vbandp.com/SearchResult.a...eed%20bleeders

Dave Zuberer

[Craig S.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Speedbleders......see link.....Craig




Speed Bleeders

[Rob A.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

I've had one of the right rear bleeder valves open for over 2 hours and not a drop of fluid yet.....I'll keep trying.....there must be an awful lot of air in there.

[Harmon C.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Rob If the master cylinder hase been sleeved I have been told the system won't gravity bleed. I can not make a resleeved M/C's gravity bleed and have had the same results you are having. Lyle

[Craig S.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Lyle - I am having a hard time understanding why sleeving would have any bearing on bleeding, if the holes are all drilled correctly after sleeving, there shouls be no difference at all in the process....Craig

[Harmon C.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Craig Their may be a hole that is not drilled but my check was to remove the lines from the sleeved master cylinder full of fluid and they did not drip. Lyle

[Rob A.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Does the master cylinder have to be bled again, since I let the rear half run dry? If so, does just the rear half need to be bled?

[Craig S.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Rob - yes, air would have entered the rear section of the MC again, as far as your question about bleeding just the rear section, I am not sure but I believe that the piston travel may move air from the rear section to the front section when it is stroked. It would be best to rebleed again assuming both sections have trapped air....Craig

[Craig S.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Lyle - they may not drip with the cover installed, if the cover is off it should certainly gravity bleed. My cylinder from Apple hydraulics has every port carefully drilled through just as the original did. I haven't proven or disproven your theory yet though as I have not installed it or rebuild the piston and seals yet, but every orifice appears as original...Craig

[Rob A.]

Re: '67 MASTER BRAKE CYLINDER BLEEDING

Do I need to detach the both brake brake lines in order to bleed the master cylinder? The first time I did it was on a bench with fittings where the lines attach. Craig, the way it is now, I can't even get enough fluid to the rear lines to push the pads against the rotors, even pumping the pedal several times.