Do I really need this?
 

Looking to replace this potential vacuum leak. Do I need this "back flow" adapter? Or can I just replace the hose?

You only need that if you want your power brakes to work.

Where can I find this part?

I should clarify what I'm talking about not needing. Gold piece with arrow on it. Can't seem to find the part. I'm pretty sure I will break it when I replace the hose.

I drove my FB without the valve for 2 years and never had a brake issue. If someone else disagrees please chime in.

Thanks....any more input would be appreciated!

I capped mine off when my booster went bad. I was pretty hard to brake but I did stop.
I would keep it. It's durable and every first gen had them so you can pick one up off a junk car.

You need that one way valve to help keep the vacuum on the booster. Otherwise it will not hold
vacuum for very long and your brakes will be power brakes sometimes (under high vacuum ==
acceleration) and not power brakes with there is no vacuum (decel) which is when you would
want them the most.

Thanks for the info. Anybody found an alternative part for this?

Simple. Go to your local parts store with it in hand and ask for a 1 way check valve for use on the brake booster. If the part was useless why the hell did Mazda engineers put it on the car then? Theyre not going to spend 1-2 dollars per car for a useless part.

There are a lot of useless parts on 7s... the cold start fluid reservoir comes to mind. Half the emissions stuff doesn't work either after a decade, much less 3.

Beg to differ, sir; depends in some cases on your definition of "useless." The car will run with around half the ancillary parts removed. Doesn't make them useless.

Power brake assist is not essential to operation, but it's awfully nice to have. As is consistent braking performance under all conditions.

As TG pointed out, the one-way valve preserves brake-assist vacuum at the booster during low-vacuum conditions.





PS; all my 35-year-old emissions stuff works well enough to pass SoCal's enhanced smog check. :egrin:

If your not an automotive engineer you have no right to say anything on the car is useless. They put the time into designing these "useless" parts.
Again if anything was useless it wouldn't be on the car. Sub Zero starting is an exception that was a horrible idea.

My 85 GS didn't come with one of these, and it doesn't show up on the parts diagrams either. Did they not use these one way valves through the whole production run? I don't remember ever having a 1st gen with one of them in place...

I am not an automotive engineer, but I am a engineer. Every day I see things get pushed through that look good on paper or are a political move rather than a solid decision. Also as an engineer I can safely say there is always a more effective solution then the one you have made.

That being said noting on the 7's really irks me like the sub-zero. Well besides the armrest and bin joints, but that's a different problem.

Also, @ DD it does totally depend on your definition of useless, and I certainly live in a state w/o emissions checks :lol: The brake thingy (clearly I know what I'm talking about here) is clearly not one of the useless things. Uniform and responsive breaking is something I am fond of.

1980 parts fiche, Section 4340A, Page 2.E.9, reference # 43370, part # 0233-43-770 "Valve, Check"

1979 parts manual, Page 157, Section 4340A, Same reference number, Same part number.

Looking at the 84-85 fiche, it looks as if the check valve may be built into the brake booster, inside that round boss that the vacuum inlet comes from. The previous boosters didn't have that.

Searching that part number doesn't get any results.

That's because it's from original docs - Mazda changed their numbering scheme some years back. Dealer can translate it, if it's still available.

The one way valve is found on early brake boosters. The later bigger ones like 81-85 don't use them. I think they're built in.