Brakes


by Jimmy Hemphill and Keith Richmond
Last updated: 20 September, 1996

Contents:

Introduction:

 This document will evolve durring the next several months. We do not intend to be your "One Stop Miata Brake Shop." We do hope to provide a broad band of information that will be helpful to most Miata owners. If you find this information useful, use it. If not, please help us improve its content.

Comments and Suggestions:

Replace your brake fluid at least every 18 months. When you replace the brake fluid, also make sure that you replace the clutch fluid as well. Brake fluid is corrosive, and replacing it frequently is much cheaper in the long run than replacing brake parts.

When adding or changing out brake fluid, use only fluid conforming to SAE J1703 or FMVSS 166, DOT 3 or higher specifications. Using any other type of fluid in the system will damage the seals, which could result in a system failure.

Avoid mixing different brands of brake fluid, and when you replace your hydraulic fluid, try to completely flush the old fluid out of your system.

Just like my first grade teacher, Miss Champion, told me - neatness counts, and good housekeeping is important. Brake parts are designed to work with only pure brake fluid. If your brake fluid becomes contaminated, it will start to destroy seals and hoses almost immediately.

Be careful with brake fluid. It is corrosive, and it will eat your paint.

Miata rear calipers aren't self-adjusting. It is a good idea to check their adjustment when you replace the system's hydraulic fluid. Proper adjustment will give you a higher brake pedal and less travel in the emergency-brake handle.

The Miata Club reports that "rear brake calipers have a tendency to freeze up if proper care has not been given." They recommend (see Tech Tips on page 26 of the Winter 1995 issue) that members having brake work done on their cars make certain that the pins on which the caliper halves slide are well coated with a special high temperature grease. The grease can be found at most auto parts stores.

If you modify your car's brake system, make certain that anyone driving your car completely understands how your modified system drives. Remember high-performance brake components that work for you may not work as well for your significant other.

Before you replace your brake pads with high-performance pads, make sure you talk with several people who are familiar with the pads you are considering. I would never buy high-performance pads from someone who did not have first-hand experience with the pads they were recommending.

Don't buy Cross Drilled Rotors unless you ask lots of questions (see performance high-grade section). Make sure that you buy the rotors from someone with first-hand knowledge of the rotors' performance, reliability and durability.

If you work on your Miata, buy a shop manual and use it. I have never made a mistake that I could not have prevented by reading the manual in more detail, by following the manual more precisely, or by visiting with one of the dealers that sponsor Miata.net. "Go slow (plan thoroughly and work methodically) to go fast." My wife doesn't seem to have problems with this concept. I like to tear stuff apart before I read the shop manual. My wife generally gets better results.

Develop a relationship with one or more of the Miata.net sponsors and join a Miata club if your can. I'm a member of the Houston Miata Maniacs. Keith is a member of Mazda Sportscar Club of Washington. Every club has at least one tech expert and almost everyone is willing to help. I buy nearly all my after market parts from one dealer, a Miata.net sponsor, who is very patient and extremely helpful. I would not buy high-performance brake parts without first consulting with him.

Fundamentals and Mechanics:

Rather than "re-inventing the wheel" we are including a link to Automotive 101:

This section of Automotive 101 provides both a general and a more detailed discussion of brake systems. It also includes an excellent section on anti-lock brakes.

Automotive 101 also includes sections on other automotive components (cooling, electrical, exhaust, etc.).

If you know of a better site, please let us know.

An Internet Miata Brake Job (by Keith Richmond):

Click here to view the brake pad change page.

Improving Miata Brake Performance:

Performance improvements fall into three broad categories: 1) high-grading brake pads and fluid, 2) replacing brake lines with stainless steel hoses, and 3) installing cross drilled rotors. The Fall 1995 Miata Magazine includes a review of Jackson Racing cross drilled rotors, stainless steel brake lines, and high-performance brake pads (see the On The Market section on page 50).

High-grading Brake Pads and Hydraulic Fluid:

High-performance brake pads and hydraulic fluids fall into the same category as motor oil. Everyone has an opinion, and what works well for one person may not work at all or another.

High-tech compositions can significantly improve brake pad performance. They may require significant time to warm up when first used and may generate lots of brake dust. They may also require unique break in techniques (often called "bedding the pads"). Again the best thing you can do is to talk with other Miata owners, visit with various dealers, and select a pad that will work for you. Remember what works well on the track may be a nightmare to live with on the street.

Make certain that you understand how to properly install the pads (special coatings may be required) and how to break the pads in. Also make certain that you use a brake fluid compatible with the pads' performance.

High-performance brake pads are relatively inexpensive - one to two hundred dollars a set. They can significantly improve your car stopping power and are a particularly good upgrade when you replace your factory pads.

Stainless Steel Brake Hoses:

Regular brake hoses expand when you apply pressure, giving the brakes a "spongy feeling." Stainless steel brake hoses don't expand, significantly firming up the brake pedal feel. They have a minimal effect on brake fluid temperature and were not intended to be used for this purpose.

The Miata Club likes stainless steel brake lines well enough to call them one of their favorite "things to do to a Miata." They are relatively inexpensive - less than $200 a set and seem to be an obvious system improvement.

Cross Drilled Brake Rotors:

Cross drilled brake rotors are a controversial issue. Most reasonable people agree that drilled rotors will improve braking performance.

Proponents of cross drilled rotors believe that they: 1) "dramatically improve brake performance by reducing fade, rotor glazing, and pad wear," 2) "radically increase cooling," 3) "significantly improve wet weather performance," and 4) "decrease unsprung weight."

Others believe that the lower mass of the drilled rotors causes them to heat up faster and to higher temperatures than the non-drilled rotors. They believe that drilling decreases the structural integrity of the rotor and that this structural weakness, and the increased heat that drilled rotors generate, can lead to premature warping or catastrophic failure.

One thing is certain "They look marvelous." For four to five hundred dollars, your Miata can have brakes that look as good as the ones on your local drug dealer's Porsche.

I plan to buy cross drilled rotors. I also plan to thoroughly research various manufacturers and will only buy rotors from someone that uses cross drilled rotors on a car they drive frequently on the street. I would be leery of re-drilled factory rotors and would be most likely to buy a product from a company that does lots of Miata business.