NB Brake Proportioning valve Part #/Rebuild kit?

hks_kansei · Postby **hks_kansei** » Mon Sep 17, 2018 1:05 pm

The prop valve on my car is leaking, which explains the sh*t pedal feel.

Anyway, I can only find the yankee parts lists, and I suspect their NB8A valves were different since they had ABS, and the whole steering on the wrong side thing.

Does anybody have a link to, or access to, the Aussie part numbers?

Or, a link to a rebuild kit for the valve?

Cheers.

manga_blue · Postby **manga_blue** » Mon Sep 17, 2018 6:06 pm

You've probably already seen this on the US parts diagrams. Page 4360A shows the prop valve for the non-ABS option as 43-900 which links to part number NC10-43-900. The diagram does NOT illustrate any repair kit. From that I assume they expect you to buy a full replacement valve, but you're right, there's no certainty that it's the same as the aussie valve.

As I see it you have three options: pull the thing apart and match the seals, springs, etc with generic brake parts or buy a second hand unit or replace it with a Willwood adjustable valve.

hks_kansei · Postby **hks_kansei** » Mon Sep 17, 2018 6:12 pm

Yeah, that number matches my parts listing.
Visually from the diagram it looks the same, but obviously I can't guarantee that it is in real life.

Also, I'm assuming the US spec non-ABS NB8A had their "small" brakes, which I believe are NA6 sized? (their "sport" brakes were our standard NA8/NB8A ones werent they?)

Does the NA6 have the same valve/Bias as the NA8/NB8A in Aust?

I'll contact Mazda Aust with the number and see if it matches their listing, then probably buy it for 1/3 the price from Amayama

I'll leave the Wilwood option as a last resort, I've got no need for bias adjustment, and have always found the stock NB brakes to be fine for my uses.
Plus, I can't be arsed setting it up

rossint · Postby **rossint** » Mon Sep 17, 2018 6:37 pm

US centric but I haven’t heard of them having different brake options on the standard cars. As you can see the cars got more rear bias through the years with the 02 ABS going to an electronic system to control bias.
https://www.flyinmiata.com/tech/stock_bpv.php
Sport brakes normally refer to the NB2 “big” brakes.
Unsure if the US valves are any different to AU models but it would surprise me if they were. Best hope is that someone whose upgraded to an adjustable valve has the factory one kicking around.

manga_blue · Postby **manga_blue** » Mon Sep 17, 2018 6:42 pm

Amayama stock it for $151. Maybe you could trawl Google Images for pics of the master and prop valve on recognisable NB8As to see if you get a bit more certainty. I'd be very wary of using valves from earlier cars. NA6 valves were shyte because of excess balance towards the fronts, they improved the NA8 valve a little bit but it was still pretty bad and then finally got it almost right with the NB8A curves.

hks_kansei · Postby **hks_kansei** » Wed Sep 26, 2018 4:35 pm

For now i've grabbed a secondhand one from the wreckers to try.

If it works, i'll then use my current, leaky, one to open up and see if there's anything serviceable inside, or if the seals etc are all proprietary.

If the secondhand one leaks, i'll probably just grab a brand new one.

Here's hoping this fixes my currently sh*t brakes.