2022 ND MX-5 Brake Bleed Nightmare

[ChrisB118]

I'm hoping to share my experience and get some advice, I have a 2022 ND Miata, and I've done several modifications to it, I just tried to bleed my brakes for the first time, and I'm having an absolute shamble of a time getting the pedal to feel correct again. The main problem I have is the pedal is very soft at the top of the travel, then firm at the bottom of the travel. The pedal is very firm when pumping the brakes with the engine off, there seem to be no noticeable leaks in the system. I've bled the brakes multiple times, putting over 36 oz (3 bottles) of Prestone DOT 5.1 brake fluid through the system. (is this fluid not good for some reason or another that I don't understand yet? If so, please enlighten me its about the only thing available in local parts-stores for a "high-temperature" fluid (I track my Miata fairly regularly), and I've bought a bunch...)

I have the Goodwin Racing 12.88 BBK in the front, with the 4-piston Dyna-pro Calipers
Link - https://www.good-win-racing.com/Mazda-P ... -1725.html
and the Goodwin Racing Ultralight 4-piston rear caliper upgrade
Link - https://www.good-win-racing.com/Mazda-P ... -1968.html

Any advice would be much appreciated. I think I have air in the ABS system somehow (I broke a bleeder screw on the rear and the master cylinder went dry while I was sourcing a replacement) The ABS does activate, and I did activate it a couple of times by sliding the car on a gravel lot in between two different attempts at bleeding the brakes. I know the ABS system activated, but it also seems to be particularly weak in my car.

I do all my work at a local rental garage, so solutions that leave the car up in the air for a long time cost a fair bit of $$$ since I need to reserve the lift time, any kind of advice would really help a lot. I tried to activate the ABS manually using an OBD scan tool, but this also did not work with multiple OBD2 tools that should have that feature.

[Brian]

Sorry if this sounds basic but now and then we have seen folks not understand that these calipers have bleeders on both banks, inside and outside halves, four valves total per caliper with two facing up and two facing down. Over time we crack open the down facing valves to release any water in the system but on first install it should be just the TWO up facing bleeders per caliper. Thus, if bleeding only ONE bleeder per caliper that leaves big air bubble in the other half of that caliper.

The other issue we see folks have is that they try and bleed through threads of the brass plug that holds the bleeder, not understanding that the bleeder is the very tiny black valve in the middle of a brass plug, and not the brass plug itself. So, if using wrench that is fitting around the outside of brass plug that is not correct, should be tiny wrench on just the black valve that is in middle of brass plug.

To make this even more clear, wrench to bleed on BLUE arrow black valve and NOT the red arrow brass plug.