Prop Valve on Front Brakes?
 

We've run the Wilwood dual master on the car for years with NB brakes/ST43s and been extremely happy with pedal feel/performance

This year, we moved to the 11'' box mount set up with Dynalites. Race event one we boiled the fluid and got brake fade when pushing really hard. Race two, light pedal pressure directive and no issues, through pad wear was more than expected.

Event two, we increased front spring rate (for a different reason) and found we could barely go to the pedal at all, without locking the front. Pedal feed back has been very vague as well.

Should I be trying to solve this problem with pad selection, or am I on the right track dialing out pressure from the master to the front brakes?

Track only car/ 2,150 weight/ aero/ RS4's

I'm assuming the dual master doesn't delete the stock prop valve, in which case you'd actually want something like the wilwood adjustable prop valve for the rear lines. If you don't have stock prop valve then just ignore all this. Instead of cutting pressure to the fronts you just need to move the "knee' further out on the rears. If OEM prop valve is still in there then at a certain MC pressure it starts cutting pressure to the rears and the wilwood adjustable prop valve allows you to move that around. I'm installing one now and in a similar situation (2351lbs with me in it, ~175whp, air dam/wing, 1100f/600r spring, 225 skreets RT660 or V730). I was already locking fronts well before rears on OEM NA8 setup and now with BX11 (Gloc R12f/R10r) it hasn't gotten any better. Can't comment on pedal pressure as I just deleted my booster with the honed kit b/c I like the considerable pressure of manual brakes, BUT everytime I've driven an enduro miata with decently aggresive brakes (DTC60) on RS4's I've felt like I could barely touch the pedal with my big toe without getting lockup.

Anyways, my guess is you need wilwood prop valve on REAR lines, but I'm not sure how dual master differs from OEM regarding prop valve.

Here's some info on prop valve near end of page
https://supermiata.com/supermiata-brake-faq.aspx

I think you've got problems other than proportioning here.

Fade and boiling fluid make me question bleeding procedures, pad choice, and the age/quality of the fluid. Is that sorted out now?

Do you have a proportioning valve for the rear?

Definitely, absolutely read the SuperMiata page linked above, many times.

i'm also on dual wilwoods...
do you mind showing a pic and the specs of the rear/front masters?

thanks!