NB Brake Booster Upgrade
 

I recently upgraded to NB brakes on my 93 NA. Brake pedal is mushy, I'm told I should get an NB booster, and master as well.
Can I get some info on what model year I need? I have ABS.

Make sure ABS is completely bled of air?
https://www.miataturbo.net/suspensio...-brakes-57742/

There are 3 different booster sizes, 2 master sizes (separate from whether or not they have ABS) from 1.8 cars. It would be easiest to get a master/booster pair off of a wrecked 2003+ if you want to ensure that you have the big master and a bigger booster that play well with each other. Non-ABS have an extra port that the ABS models don't have. On my non-ABS NB I only had to do minor finessing of the hard lines to get everything to fit together. I don't know if that is the case with a 1.6 NA.

The following thread by Keith Tanner will be relevant to your interests: Some interesting brake information

I have the "Sport" booster from a MSM in my car with stock 1.8 brakes. Paired with the bigger (15/16") master the pedal effort is very slightly less than what I had stock, but with a noticeably firmer, shorter-stroke pedal. I like this. The non-Sport NB2 booster is considerably more powerful and would yield lower pedal effort.

Ya'll just love linking posts from 10+ years ago. lol

Ive been on eBay, rockauto and googling images and I see a lot of different looking boosters and masters. there are abs and non abs version of each and then there are different looking pressure valves too. Seems a lot more than just 3 different boosters, and 2 masters.

here is my setup in 93. looks a lot more like a 94 model than it does what other 93 with abs have
https://i.imgur.com/JbleeQp.jpg

Does anyone have the Mazda part numbers for the different masters and boosters?

This info is all in the thread started by Keith at FM over on miata.net. The link was posted above. Basically the booster and MC from a 01-05 car is what you want, which ones specifically depends on your set up and preferences for travel, effort, feel, etc.

Booster Ratios
1990-00: 4.74:1 <- this is a bit approximate, as Mazda gives a range of output pressures as acceptable
2001-05 non-Sport and Sport with ABS, except for MSM: 9.7:1. Yes, that's about double. This booster is visibly fatter, and I suspect it has dual diaphragms inside instead of a single.
2001-05 Sport without ABS and MSM: 6.4:1

Booster part numbers for 01-05 Cars
non-ABS, non-Sport(a.k.a. non-Hard) is part # N066-43-800A
non-ABS, Sport(a.k.a. Hard) is part # N067-43-800A
ABS is part # N069-43-800
MSM is part # N115-43-800

MC sizes
Non-sport- 7/8"
sport- 15/16"

Caliper piston sizes for reference
non-Sport, front: 2.01"
Sport, front: 2.125"
non-Sport, rear: 1.25"
Sport, rear: 1.375"

If you read through the thread, a lot of folks in there recommend the Sport (non-abs) booster with the MC from a 93-95 929 (1" diameter) for the best overall pedal feel and modulation, short of going to manual brakes and dual MCs.

I run this setup and absolutely love it. Though my car is an NB2 with sport brakes and no ABS, so it already had the right booster and the larger sport calipers. Feels even better now that I upgraded to the STR42/STR21 kit from V8R

The Miata.net thread is good, but note that the question of which NB2s got which booster is more complicated than presented there. I've seen multiple unmodified cars where they didn't match.

I have the 6.4 NB2 booster (the singleton, came out of a sport, ABS car) with a 929 1" master and I agree, it's a good mix with a BBK for a track car (TSE Wilwoods on mine)

--Ian

That Miata thread is good, but is also misleading by making claims that are not true.
Generally, if In want a sifter brake pedal feel, I want a lower ratio brake booster. But according to that thread the NA1 has the lower ratio booster.

A lower ratio booster will make your pedal "stiffer" in the sense that it'll take more pedal effort to get a given level of braking. It'll have no effect on the amount of travel the pedal needs to reach a certain brake line pressure. To change that, you need a bigger master cylinder, which increases the pedal effort. You then get a stronger booster to bring the pedal effort back to where you want it.

The Miata.net thread was started and researched by someone who has more aftermarket Miata knowledge than most anyone. Keith Tanner has literally written books on the subject and is the resource for LS swaps (he was interviewed by Road & Track when they tested Flyin' Miata's LS ND, for which he did much of the engineering work). I'd make sure I knew what I was talking about before dismissing what he says.