cb vs. cv master brake

[cedryck]

Evening Gents.
This owner of a 65 2a is having difficulty expleting air from a cb type master, any comments? Has anyone swapped out a cb to a cv, seems like the design is less likely to trap air in that large cavity at the end of the master. Any comments appreciated.

[Momo]

Best thing you could do is upgrade to the vacuum assist brake system. It eliminates the angle completely. You'll need a Series III brake pedal tower, master and servo, clutch master, and some plumbing modifications. The CB is a real bear to get right.

This might help you out:

http://aluminumfriend.blogspot.com/2007/01/power-brake-upgrade-for-pre-1968-land_02.html

[cedryck]

Thanks, I am in the interest to keeping this vehicle as original as possible, not going to apply the vacume operated brake system. I would like to hear from someone who has eliminated the cb master with either a cv, or willwood type master, thanks all the same.

[cousindave]

momo: great website!!! Looks like you've been taking tips from Rip Van Winkle.

[I Leak Oil]

You can switch to the CV. I don't remember if the line fittings are the same though. I never had an issue with the CB on my truck though.

[cedryck]

thanks, I will and feel the cb is just poor by design, that big cavity at the end tends to trap air, making it difficult to expel.

[lew_sa]

Bench bleed the CB before you install it.

[shock]

It may have been my imagination but I jacked up the front end of my '66 88 after having some of the same trouble and it seemed to do the trick for me. I think I read somewhere about it and didn't have much to lose at that frustrating point. Maybe changing the level caused the air bubble to move to a better spot or it moved out through the reservoir. Or it was all a dream. Oh and if you do, please use jack stands and wheel chocks. Good luck.

[kwd509]

is there any downside to switching to the CV cylinder for the brake master?

[cedryck]

As far as I know, now issues in switching from cb to cv, I do believe that at least one fitting is different, and requires changing. Yes raising the front end will help eliminate air trapped at the back of a cb. Loosening the output pipe so it bleeds while preasure bleeding will help too. 14psi into the system will help expel air through wheel cylindar taps.

[gudjeon]

I had a '57 ser1 CB and it was a bugger to bleed. What I ended up doing was getting a help to put a few pounds of air pressure into the reservior breather hole. Held a rubber-tipped blow gun right on the hole and applied some air. Then I bled each wheel as normal. Just about 8-10psi. Worked on mine and bled out lots and lot of tiny bubbles. I pushed about a quart and a half through this way.

[cedryck]

yea, I have preasure bleeder and will use that, this seems like the only reasonable way to bleed, using pump and hold method (like any usa car) just does not work well.

[scarter]

new issue

Using a new CB, have bled lots of very tiny air bubbles out. After more than a pint of fluid, still lots of tiny bubbles, however, upon pump stroke to floor to expel fluid/bubbles, pedal sticks down and has to be retracted by hand each time. It's as if the return spring isn't there. Ideas?

[I Leak Oil]

Is the returns spring there?
As a matter of habit I don't bottom out the pedal when bleeding a system. I like the idea of keeping the cylinder within it's normal working range.

[scarter]

Return spring's in place.