2003-2012 Mazda RX8 Parking Brake Problems and Adjustment

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2003-2012 Mazda RX-8 uses a cable-operated hand lever in the center console that works a screw-type parking brake built into each rear disc caliper. When the lever pulls up too high, will not hold on a hill, or a rear wheel drags after a pad change, the cause is almost always cable stretch, a rear caliper piston that was not set correctly, or a sticky caliper mechanism, not worn drum shoes, because the RX-8 has no rear drums.

This guide walks through how the system is laid out, how Mazda says to check and adjust it, and which rear parts to replace when adjustment alone will not fix it.

How the RX-8 Parking Brake Works

Mazda's service manual lists the system as a parking brake lever with a parking brake switch (the switch turns on the red brake warning light). From the lever, a front parking brake cable runs back to the rear parking brake cables, which connect to an operating lever on each rear caliper. An adjusting nut at the lever sets how much slack is in the whole system.

At the wheel, the rear caliper does double duty. The hydraulic piston clamps the pads for normal braking, and when you pull the lever, the cable rotates the caliper's operating lever, which mechanically pushes the same piston and pads against the rear rotor. That design has two consequences an owner needs to know:

• The rear piston is threaded. It cannot be pushed straight back with a C-clamp like a front piston. Mazda specifies rotating it clockwise with a special service tool while pushing it in.
• Rear pad wear and parking brake lever travel are linked. As the pads wear, or if the piston is not set correctly, the lever feel changes.

Common RX-8 Parking Brake Problems and Symptoms

Lever pulls up too high or clicks too many times

This is the most common complaint. Cable stretch, worn rear pads, or a rear piston left in the wrong position after a pad job all add travel. The car may still hold on flat ground but roll on a steep driveway.

Parking brake will not hold the car

Beyond excessive travel, look for contaminated rear pads (fluid or grease), glazed pads, a seized caliper operating lever, or a rear cable frozen inside its housing. A seized cable usually leaves the lever feeling hard with little travel instead of loose.

Rear brake drag or heat after releasing the lever

If a rear wheel is hot after a drive or the car feels like it is pulling against the brakes, the parking brake may not be fully releasing. Mazda's cable installation note says to verify that the caliper operating lever returns to its stopper with the parking brake lever released. If it does not return, the cable is too tight or binding, or the caliper mechanism is sticking.

Brake warning light stays on, or never comes on

The parking brake switch at the lever controls the light. Mazda's procedure has you pull the lever one notch and confirm the light comes on. If the light stays on with the lever fully down, check the brake fluid level first, then the switch. The service manual gives a continuity check for the switch with its connector unplugged.

How to Check Parking Brake Stroke the Mazda Way

The RX-8 factory procedure measures lever travel by counting notches under a set pull, not by feel. The steps from the Mazda service manual:

1. Depress the brake pedal several times. This sets the rear caliper pistons against the pads.
2. Pull the parking brake lever two or three times and release it.
3. Slowly pull the lever at a point 50 mm (1.97 in) from its end with a force of 98 N (22 lbf), counting the clicks.
4. Compare the count to the notch specification in the factory service manual. If it is outside that range, adjust.

The pull point and force matter. Yanking the lever as hard as you can will always give a lower count than the spec is written for, so a good-looking result from a hard pull can hide a system that is actually loose.

How to Adjust the RX-8 Parking Brake

Adjustment is done at the lever, not at the wheels. Per Mazda:

1. Depress the brake pedal several times.
2. Remove the service hole cover on the rear console to reach the adjusting nut.
3. Turn the adjusting nut to bring lever travel into specification. Keep the parking brake released while you turn it.
4. Pull the lever one notch and verify the parking brake warning light comes on.
5. Verify the rear brakes do not drag. With the rear of the car safely on stands, in neutral and with the lever down, both rear wheels should spin by hand without binding.

Two cautions. First, do not use the adjusting nut to cover up a rear caliper problem. If the lever was fine before a pad change and is high after it, the pistons were probably not set correctly, and tightening the cable can leave the brakes dragging. Second, over-tightening pulls the caliper operating levers off their stoppers, which causes drag, heat and fast rear pad wear.

Rear Pads, Calipers and Rotors: When Adjustment Is Not Enough

Setting the rear piston during a pad change

Mazda's rear pad replacement procedure disconnects the parking brake cable from the caliper and removes the caliper. On reinstall you clean the exposed part of the piston, then rotate it clockwise slowly with the special tool while pushing it fully in until the piston grooves line up in the position shown in the manual. The inner pad has a projection that must sit in a piston groove. After the job, Mazda has you pump the pedal and check three things: the pad projection is seated in the piston groove, parking brake lever stroke, and brake drag. A pad projection that misses the groove is a classic cause of a high lever and uneven rear wear.

Pad wear limit

The service manual gives a rear pad minimum thickness of 2.0 mm (0.079 in) and says to replace pads as a left and right set if either side is at or below it. For replacement, we carry Hawk HPS street rear brake pads for the RX-8, the Hawk HP Plus rear pad set for autocross and spirited driving, and EBC Bluestuff NDX rear pads for track days. Hawk notes its compounds are made for iron rotors, not carbon ceramic. Browse more in our brake pads collection.

Rotors

Because the parking brake clamps the rear rotor, a rear rotor that is scored, worn below its minimum thickness or running out of true reduces holding power and can cause judder. If you are replacing rear pads on worn rotors, do both. The EBC USR slotted rear rotors for the RX-8 with standard suspension fit this car, and more options are in our brake rotor collection.

Calipers and cables

If the operating lever on a caliper will not return to its stopper with the cable disconnected, the internal mechanism is sticking and the caliper needs to be rebuilt or replaced. Check brake calipers for your car. If the caliper lever moves freely by hand but the cable will not slide in its housing, replace the cable. Rusted cables are common on cars from salt states.

How Hard Is This Job?

Torque all caliper and mounting support bolts to the values in the factory service manual, and after any rear brake work redo the stroke check before driving.

Frequently Asked Questions

Does the Mazda RX-8 have drum-in-hat rear parking brakes?

No. The RX-8 parking brake is built into the rear disc calipers. The cable operates a lever on each caliper that mechanically pushes the rear piston and pads against the rotor.

Why is my RX-8 parking brake lever higher after new rear pads?

Usually the rear pistons were not rotated in and aligned so the pad projection sits in a piston groove, or the pedal was not pumped afterward to bring the pistons out. Recheck the caliper installation before touching the cable adjuster.

Where is the RX-8 parking brake adjuster?

At the lever inside the center console. Remove the service hole cover on the rear console and turn the adjusting nut with a deep socket while the parking brake is released.

Can I push the RX-8 rear caliper piston back with a C-clamp?

No. The rear piston is threaded for the parking brake mechanism. Mazda specifies rotating it clockwise with a rewind tool while pushing it in. Forcing it straight back can damage the internal mechanism.

How do I know if the parking brake is dragging?

With the car safely supported, in neutral and the lever fully down, spin each rear wheel by hand. It should turn without binding. Also confirm each caliper operating lever sits against its stopper when the lever is released.

Sources

1. Mazda RX-8 service manual: Parking brake lever inspection and adjustment - stroke check at 50 mm with 98 N, adjusting nut via rear console service hole, warning light and drag checks
2. Mazda RX-8 service manual: Parking brake system location index - system components, lever and parking brake switch
3. Mazda RX-8 service manual: Rear disc pad replacement - cable removal, clockwise piston rotation, pad projection in piston groove, post-job checks
4. Mazda RX-8 service manual: Parking brake cable installation note - operating lever must return to stopper with lever released
5. Mazda RX-8 service manual: Rear disc pad thickness inspection - 2.0 mm minimum, replace as a set
6. Mazda RX-8 service manual: Parking brake lever removal and installation - propeller shaft and front console removal, cable and switch layout
7. Hawk Performance HB378N.565 - rear pad fitment for the RX-8 and iron-rotor-only compound note