Brake bleeding a dual system

[360gts]

Just completed the build on my vintage race mini....time to bleed the brakes.
It has a complete new brake system...calipers, lines, rear cylinders and a new MS front/rear master. (no servo)
Heard many horror tales about bleeding this setup.
So, before I tear my hair out (what is left)....any tips/suggestions as to the best way to do this.

[Craig]

Dermott ,

I’ve been using the Eezi bleed from minispares.
http://minispares.com/product/Classic/A ... o%20search

Seems to work a treat.
Changed few of these tandem master cylinders lately.
I only run around 20 psi for pressure.

Craig

[360gts]

Dermott ,

I’ve been using the Eezi bleed from minispares.
http://minispares.com/product/Classic/A ... o%20search

Seems to work a treat.
Changed few of these tandem master cylinders lately.
I only run around 20 psi for pressure.

Craig

Tried the vacuum unit and the pressure unit....no luck so far.....just doesn't seem to want get the fluid to the rears!

[EAVB]

I had similar trouble with one of these I was doing for a friend recently. After faffing around for a while I ended up reverse filling the system via the rear bleed nipples using a garden sprayer filled with brake fluid and slackening the unions at the master cylinder end.

After that the system bled straight away. It's not as cowboy as it sounds! I have used this method in my day job for years and it makes a cheap pressure bleeding kit.

[miniminor]

Fluid in mine was well overdue a change. Used my vacuum unit and made a balls up, obviously introducing air into the system and 'losing' the pedal. Bought a gunson eezibleed and whole system changed in about 15 mins.

[Spider]

Usually the hard part is getting a flow from the Master in the first place. I find a pressurising tool best for that, once you can get fluid from the tube nuts on the Master, then old school pedal pumping I find not only quickest, but also removes the air the best too.

I don't like vacuum bleeders are the seals of the type in the Master Cylinder and Wheel cylinders are not designed for this and can draw air in to the system past the seals, they are designed to seal under positive pressure, not negative. It's also highly likly that the Vacuum Bleeder is closing off the Rear Wheel Shut Off Valve and so that's why there's no fluid to the rears.

The workshop manual for the early Masters (like you have) says that both front and back need to be bleed at the say time. Of course, in the event of a system failure, the whole idea of a Tandem arrangement is to leave one circuit operational, so this clause in the manuals never made sense to me. The PDWA Switch can (and should) Trip when bleeding one circuit at a time and will need resetting following bleeding. That's supposed to be achievable by removing the switch and standing on the pedal hard to re-centralise the shuttle in it, though often they need some help by moving the shuttle through the switch port. If you aren't using a switch (which I would think on your Race Car you aren't), then I'd suggest removing the PDWA Valve altogether as its only purpose is to activate a fail switch.

[mascher]

For new master cylinders, especially the tandem type, I always bench bleed them. It seems to help.

Kelley