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Complete adjustable brake proportioning kit

Complete adjustable brake proportioning kit
Complete adjustable brake proportioning kit
Everything you need to install an adjustable brake proportioning valve on your Miata!

Made in the USA

Exclusive to Flyin' Miata

Availability: In stock



One of the best ways to get the most out of your brakes is to adjust the brake proportioning, or bias. The ideal brake bias depends on your ride height, the amount of traction you have (both due to your tires and the surface you're driving on) and the specification of your braking system. You always want the front brakes to lock up first for stability reasons, but Mazda was extremely conservative and so the rears never have a chance to make much of a contribution. This adjustable proportioning valve allows you to adjust your brake bias for the perfect setup. We always have a way to adjust our brake bias in our competition cars. The valve allows you to adjust the rear line pressure from 43% to 100% of the front.

The kit includes everything you need to make installation very easy. No flaring or line bending required! The fittings are made of brass to ensure a better seal both on the flare and the tapered pipe threads when compared to harder materials. Compatible with all 1990-05 except those with both factory-installed Sport brakes and ABS. If your car has ABS but not the Sport brakes, this proportioning valve kit will still work for you. This kit is for NA and NB Miatas. The NC and ND cars with ABS use electronic proportioning, and the non-ABS NC would need two of these to work properly so we don't recommend it.

Will fit any car that uses metric brake lines and inverted flares, such as Honda or Toyota. Most Japanese imports should be able to use this proportioning kit.  Note that we cannot confirm fitment in non-Miata applications, and we have had reports that some other brands have an unthreaded "nose" on the end of the flare nut that will prevent proper engagement with the threads on this part.


  • Wilwood proportioning valve
  • M10 inverted flare to NPT adapters - FM exclusive parts!
  • M10 inverted flare union
  • Loctite 545 Thread Sealant

Warning - having too much rear bias can make your car very unstable. Please spend some time testing in a controlled environment.

Additional Information

Additional Information

Part number 14-76240
Fits: 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 2002
Manufacturer Wilwood
Flyin' Miata exclusive Yes
Fits Exocet? Yes
Proposition 65 Warning: Cancer and reproductive harm
California emissions No

Customer Reviews 3 item(s)

Easily worth asking price, works beautifully.

Only issue I had was with the union fitting provided with the kit. I was getting a brake fluid shower upon any pressure in the lines. Picked up another union fitting swapped em out and all is well.
Review by Archie / (Posted on 7/23/2020)
Must buy IMO with caliper purchase
Super glad I picked this up along with my caliper purchase. After the rear calipers were installed, I was able to feel my rear brakes doing their job for once. Install was quick but had to bend stock brake lines ever so slightly to line up with the ports.
Review by Ben / (Posted on 12/4/2019)
Make those rear brakes do some work...
In a stock configuration, the rear brakes on an NA Miata do almost nothing (except hold the car with the e-brake). I hope you never learn why you want one of these. I was racing my '90 Miata in a World Racing League endurance race at Circuit of the Americas during a torrential downpour. The front wheels would lock up braking into every turn. I had to resort to aggressively engine braking. If I had the proportioning kit, installed at the time, I could have just dialed in more rear brakes, saved my engine, and had faster lap times!
Review by Eric / (Posted on 2/21/2017)
Click here for instructions for this part.