PB distribution block

[Ted Z.]

Is it true that the distribution block (db) is merely to trigger a switch in the event of a brake fluid problem? Is it true that if the shuttle valve is tripped, one cannot bleed brakes until the valve is recentered? Do I need the recentering tool when bleeding brakes even if the valve is centered?<br />
All brake bleeders are gravity bleeding just fine and I do not have brake light showing on dash. As such, does that mean the shuttle valve is centered and I do not need the tool to bleed the brakes.<br />
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As an aside, brake bleeding has been a pita. I changed all calipers (rebuilt) and new master (3 of em ). Rubber lines are now braided stainless. No leaks detected anywhere. I did bench, buddy, and gravity bleeds. On other forums, I see that bleeding is not exactly a simple job. Cars been up on blocks for a month. Thanks for assisance. Ted 64289

[Domenic T.]

Re: PB distribution block

Ted,
The valve has to be centered. If I remember when either front or back brakes go, the valve moves to ground the brake light. Many make the mistake when bleeding and pump the pedal which will cause the shuttle valve to move and ground. I remember that it was not hard to center the valve.
Front and rear have to be bled before testing the pedal, and some test it after bleeding one system.

Dom

[Ted Z.]

Re: PB distribution block

Thanks Dom, As you know, the block is not easy to get to. how specifically did you recenter the valve? do I need the tool to keep it in place during bleeding? as I indicated, i have no brake light and all bleeders are flowing during gravity bleeding. Looking forward to your response. Im guessing 99% of C3 owners struggle with bleeding and it has to do with the recentering issue.

[Domenic T.]

Re: PB distribution block

Ted,
it's been years, but I remember removing a fitting on top of the block. That may have a wire on it? and fishing the shuttle valve to center.
Wow, today on newer cars nothing is easy to even see.
I am sure one will chime in and give you good advise. I have 3 pressure bleeders. One with dot 3&4, one with dot 5, and one with 5606 aircraft fluid.
I like pushing the bubbles up and toward the master cylinder. But to each his own. The best advice (almost) will be in the manual.
Dom

[Ted Z.]

Re: PB distribution block

thanks again. my block is set vertically and the switch is on the side. i cannot see how id recenter without removing block; not as easy as sounds. the top fitting is a fluid line connection. im just trying to determine if i need the srew-in tool that goes into the block in order to bleed. But, still need to get shuttle centered to get tool to bottom out and hold shuttle in place to bleed brakes. unfortunately, no videos that i have seen. hope others can help.
ted 64289.

[Owen L.]

Re: PB distribution block

Is it true that the distribution block (db) is merely to trigger a switch in the event of a brake fluid problem?

All brake bleeders are gravity bleeding just fine and I do not have brake light showing on dash. As such, does that mean the shuttle valve is centered and I do not need the tool to bleed the brakes.

Yes, it's really just a switch to indicate brake failure (via pressure difference) in either the front or rear system. If you can bleed both the front and rear and no light is activated on the dash then don't worry about the switch. It's centered well enough and will not cause issues as is.

[Ted Z.]

Re: PB distribution block

Thank you Owen! That is great news. some have posted you cant bleed if you depressed one corner. Stating it sends the shuttle off center disallowing full brake bleed. Ive been primarily gravity bleeding and stiil attemping to determine why I cant get a normal pedal. alrready returned 3 MC's. Hence I started questioning dist block and booster. Never had so much trouble R&R brakes. Ted

[Owen L.]

Re: PB distribution block

Brake bleeding can certainly be a frustrating challenge. I use a homemade lid contraption with my air compressor for a similar process to the Motive bleeder. Here's a link to a post on CF with a pic of my setup:
https://www.corvetteforum.com/forums...post1603285254

A lot of folks recommend 2-3 additional bleeds after you attain a safe braking situation. This allows road jostling and braking action to move any remaining bubbles to the calipers.