Rebleed Master Cylinder?

[clifftt]

I changed from a single reservoir to a dual reservoir master cylinder on my '66. It's power disc, rear drum. Master was bench bled on a vise, then installed. After all plumbed in, during bleeding the system, the large reservoir went dry, probably sucked some air. I've bled the system with a quart of fluid, but the pedal goes almost to the floor, and the car barely stops.

Should I rebleed the master cylinder? Any other ideas?

 

[cudascott]

If you pulled the reservoir dry you got air in the master. You can bleed the master in place with two
short lines from the outlets turned down into the reservoirs make sure the open ends are below the fluid and pump away.

 

[pishta]

make sure your rears are adjusted. If they are not they can take alot of fluid. Fronts are the large reservoirs and displace more than the drums. Your disks should be audibly dragging if they are filled as they dont back off the disk with any spring, just the action of the piston lip seal. Yes, route some bent brake lines back under the fluid levels of the reservoirs and press slowly until your assistant sees no bubbles. You can gravity bleed them too but it takes a watchful eye on the reservoirs to make SURE they dont go dry.

 

[RedFish]

Is this a entire brake upgrade or just master cylinder R&R ?
I've seen more than one reman'd master cylinder fail as if it died during the bench bleeding procedure.
I've more often seen disc brake calipers put on upside down.

 

[BillGrissom]

make sure your rears are adjusted.

Ditto, if you fooled w/ the rear shoes. I adjust fairly loose so I don't risk the shoes dragging. The pedal goes far down even though I bled well. First thing I do is back up many times, jamming on the brakes so the adjusters do their job. You should feel the pedal travel less each time. Of course, have your hand on the e-brake and insure it works before moving the car.

 

[clifftt]

Pish, Bill, I've adjusted the rear brakes to where there is a noticeable drag on the drums.
Redfish, this is a new, not reman cylinder. Calipers are right side up, bleeders at top.
For now, my money is on air stuck in the master. I'll report back.