Willwood Kit on ABS Miata - Do I use proportioning Valve?
 

Hey Guys,

I have a 2001 NB8B with the Willwood Brake kit from Flyin' Miata (4 Pot front with OEM sport brake rear). When buying the Kit Flyin' Miata advised me that the Miatas with ABS have some form of early form of EBD and not to run a Wilwood Proportioning Valve. Reading into this I have seen some mixed reviews on whether or not to run a proportioning valve but have never seen any responses from NB ABS owners if they prefer to run the valve or not. Although I am no trained professional on race/street car set up and by no means do i know anything about brakes past the basics of installing them, I do feel as if the system is very biased towards the front until ABS kicks in and then the system seems to send more power to the rear.

So, With the Flyin' miata Wilwood kit on a 2001 NB with ABS Do I or do I not run the Wilwood Proportioning Valve?

Thanks Guys :)

Wow, so no one knows?

Hey Guss- I can add a single data point not exactly the same as yours... I have a 94 NA8 with ABS, but was running the FM LBBK, which are Wilwoods sitting on all four 1.8 Non-Sport OE rotors. I did use the proportioning valve on track as intended and was able to remove rear brake as needed. ABS still engaged, but I have no idea if it was operating within normal specifications; I never tested it just to find out how it integrated with the BBK.

I can tell you that StopTech specifically engineers all of its BBKs to be fully integrated with all ABS and traction control systems and never recommends an adjustable proportioning valve. I'll assume Wilwood does something similar for my next statement: In your place I would absolutely tell you to keep your stock proportioning, booster and master. If your suspension and grip levels dictate a shift in braking bias, use brake pads to do that. Your baseline should be the same friction compounds front and rear. If you find you have too much rear brake, use a lower friction pad in the rear AND/OR a higher friction pad in the front. Using this approach should maximize the performance of the total system you have installed. I'm assuming that Wilwood designs the Front BBK to have a force output similar to the stock system, or greater.

Anti lock brakes do their own proportioning. So no need for an adjustable.

This is only true on newer Miata ABS systems (2003+, IIRC). Earlier systems still had a prop valve.

--Ian

I used a manual Willwood prop valve on my ABS-equipped racecar. The ABS worked just fine, so it seems that there is no technical reason to not use a prop valve if that is what you want to do. There may be some liability issue at work here, as far as road cars are concerned anyway, that causes the vendors to say that.

I think Emilio runs ABS in his enduro cars, he will have a view I guess.

With the prop valve installed did you tend to find you more a little more bias onto the rear brakes?

My setup was different to yours Gus (see my part-out thread for photos), I don't think my setting would help you even if I could find it. It was a scratch build, so it was just a case of adjusting it to make it work, and (not ideal) it was then set and forget, move on to other things.

All good, I've spoken with some people who work with brakes and they have asked me to test the braking with the ABS fuse pulled and see if the bias changes at all so that will be my next course of action for now. From there if it's the same bias, either a prop valve or higher friction pads it is.

What was the outcome here guss? I'm in a similar boat with my SE (MSM). Standard brake calipers, but running slotted rotors and road/track pads. Finding that the fronts are doing the majority of the work, and wanting to get the bias a bit more to the rear.I have considered a the Willwod prop valve, but no one seems to be able to say for sure if it'll work properly with the ABS and EBD in these cars.