bleeding brake master cylinder

[pedracer]

I'm just about to fit a new brake master to my non-abs 190L smiley. I'm no novice to brakes, but there seems to be a split decision on benchtop priming the master cylinder before fitting. I cannot find any fittings to do this in my workshop, Is it worthwhile leaving it for a while or will I get away without pre-priming it?

[MinorMatt]

I never have...

[pedracer]

heyho, the new master cylinder is in position. I'm staggered how easy everything came apart, the benefits of it spending most of it's life in a hot dry climate I guess. The old master cylinder piston rubbers looked in good order, but there were loads of little black specs, my guess being that somewhere the rubber is perishing in the brake master. Tomorrow eve will bring on the bleeding ceremony.... I'll do my best to get the air out of the master before nipping up the fittings.
Standby.

[cherniy_chack]

There are no features of air removal from the brake system when replacing the master cylinder.
The master cylinder is mounted on a vacuum amplifier, brake tubes are connected to it and the nuts on the tubes are tightened.
The reservoir is filled with brake fluid and nuts are released on the brake pipes.
When a clean brake fluid starts to flow out of the threads without air bubbles, the nut turns.
After the master cylinder is filled with brake fluid, air is removed from the brake system parts by unscrewing plugs on the service brake cylinders and pressing the brake pedal.
It is better to do this work with an assistant, but you can do it yourself.
You just need to have a stick of suitable length for the brake pedal to rest in the seat. And move quickly.

[pedracer]

just an update,
May be worth mentioning how i bled the master cylinder.
Install the master cylinder and reservoir dry, and couple the brake lines up to check everything lines up.
Install a catch tray and some tissue around the pipes. This gets a little squirty.
Undo the brake line connectors by 1 turn
Using a spare spare of feet, Depress the brake pedal fully, and then fill the reservoir with new fluid.
Nip up the connections.
Brake pedal up to the top, (this draws down new fluid), and then undo the connectors by 1 turn.
Brake pedal down again, nice and slowly. Fluid and air will squirt from the loose connections. When pedal fully depressed, nip them up again.
Brake pedal up to the top again and undo the connectors by 1 turn.
Brake pedal down again, Fluid only will squirt from the loose connections, if any air comes out with the fluid, repeat the process until just fluid emerges.


The bleed the lines, starting with the furthest first.

Easy.

[petethetug]

I just did the calipers and was in a hurry to get the van on the road so I went and got a "Gunsons eezibleed" £22 from Halfrauds. Probably cheaper on the net but definitely money well spent. Couldn't believe how easy it was!
PTT.

[gotgcoalman]

real men use a tube and jar and lots of swearing