1986-1996 Mazda RX7 Parking Brake Problems and Adjustment

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 1986-1996 Mazda RX-7, the parking brake does not have its own drums or shoes. The center-console lever pulls a cable to a small lever on each rear disc caliper, and a screw mechanism inside that caliper pushes the piston out. Nearly every RX-7 parking brake complaint, such as a lever that pulls too high, a car that rolls, or a rear wheel that drags, comes from that caliper mechanism or the cable that feeds it. Adjusting the nut under the console is the last step, not the first.

How the RX-7 parking brake works

Mazda's factory service manual for the 1986-88 second-generation (FC) RX-7 lists the parking brake type as "auto adjustment, rear brake," operated by a lever. Each rear caliper carries an operating lever with a stopper pin. When you pull the handle, the cable rotates that lever, and a cam and threaded shaft inside the caliper push the piston against the pads. The same threaded mechanism is the automatic adjuster. As the pads wear, the piston is ratcheted outward so the parking brake keeps the same lever travel.

The third-generation (FD) RX-7 from 1993 on uses the same basic idea. The 1993 Mitchell service information tells you to release the parking brake and disconnect the cable from the caliper before removing a rear caliper, and to rotate the rear piston back rather than pushing it straight in.

Because the adjuster only winds outward, the piston cannot be shoved back with a C-clamp the way a front piston can. It has to be turned clockwise while it is pushed in. Mazda's tool for this is the disc brake piston wrench, 49 FA18 602.

Factory adjustment specs by generation

The two generations use different lever-stroke specs, so check the one for your car. Both are measured with a firm, specified pull on the handle after pumping the brake pedal several times.

For 1989-91 and 1994-on cars, confirm the stroke in the service manual for that model year before adjusting.

Symptoms and what they point to

• Lever pulls too many notches and the car still rolls. Either the cable has stretched, or the caliper self-adjusters have stopped advancing and the pistons sit too far back. If you only tighten the cable, you are compensating for a caliper that is not doing its job.
• A rear wheel is hot or drags after a drive. The cable is too tight, or a caliper lever is seized and not returning to its stopper pin. The Mazda FC procedure has you check that lever-to-stopper clearance at the caliper before touching the cable. If the clearance is not less than 2 mm, it has you lengthen the cable, not shorten it.
• Brake pedal goes lower than it should. The FC factory manual lists a malfunctioning automatic adjuster, along with air in the system, as a cause of too little pedal-to-floor clearance. That makes a lazy rear adjuster a pedal problem as well as a parking brake problem.
• Knock from the rear over bumps. Brake and Front End notes that a screw-type caliper system with no cable tension can knock when the car is driven over bumps.
• Parking brake light stays on or never comes on. Both manuals say the warning light should come on when the lever is pulled one notch. If it does not, check the lever switch before blaming the brakes.

Why these calipers stop adjusting

The adjuster only works if the caliper lever moves freely and the threaded shaft inside is clean. On an RX-7 that sits for months, is driven without using the parking brake, or lives where roads are salted, the lever shaft corrodes, the boot splits, and the piston or adjuster seizes. Old fluid makes it worse because moisture attacks the bore. The FC factory manual calls for brake fluid meeting FMVSS 116 DOT-3 or DOT-4. The 1993 Mitchell procedure says DOT 3 and warns against mixing types. Use what is printed on your reservoir cap.

The cable is the other weak point. A frayed or rusted inner cable can stick partly applied. That holds one caliper lever off its stop and makes that wheel drag even with the handle down.

Correct order to fix it

1. Pump the brake pedal several times. This lets the self-adjusters take up any slack before you measure anything.
2. With the rear raised and supported and the handle released, look at each caliper lever. It should rest on its stopper pin, and each lever should snap back when you pull and release it by hand. A lever that hangs up means that caliper needs service or replacement. Adjusting the cable will not fix it.
3. Check the stroke at the handle with the specified pull, and compare it to the table above.
4. If it is out, remove the console cover and turn the cable adjust nut at the lever until the stroke is in spec. Brake and Front End points out that this adjuster sits under the center console on many cars and is awkward to reach, so plan for the trim removal.
5. Spin both rear wheels by hand to confirm nothing drags. Mazda's manual puts this check in bold before lowering the car. Then confirm the warning light comes on at one notch.

After rear pad work, the order matters even more. Mazda's FC procedure has you wind the piston in clockwise with the piston wrench, install the pads and V-spring, torque the caliper lock bolts to 29-41 N-m (22-30 ft-lb), then pump the pedal before checking the parking brake cable. The FD procedure also says to align the grooves in the piston with the pads. If you skip the pedal pumping, the stroke will read long and you may overtighten the cable to compensate.

What to replace at the same time

Mazda says to replace the rear pads on both sides at the same time. The 1993 Mitchell data sets the rear pad replacement point at 0.04 in (1.0 mm) of lining, and the rear rotor discard thickness at 0.71 in (18 mm) against an original 0.79 in (20 mm). A rotor worn near that limit lets the piston travel farther, which asks more of an adjuster that may already be tired. If a caliper lever is seized, replace the calipers in pairs rather than freeing one side and hoping. A parking brake that grabs harder on one side usually means the two calipers are in different condition.

Browse rear brake calipers and brake pads. If you are doing the front axle at the same time, 1986-89 cars can use the EBC Redstuff ceramic front pads or the EBC GD Sport slotted front rotors. For 1993-96 FD cars there are the EBC GD644 slotted front rotors and the Wilwood Superlite 6R front big brake kit.

How hard is the job?

A stroke adjustment is a driveway job: raise the rear, remove the console trim, and turn one nut. Replacing rear pads is moderate, but only if you have a piston tool that turns the piston. Trying to force the piston straight back can damage the adjuster. Rebuilding or replacing a seized rear caliper means opening the hydraulic system and bleeding it afterward. It is still within reach of a careful owner, but budget time for stubborn cable ends and old fittings.

Frequently Asked Questions

How many clicks should an RX-7 parking brake have?

The 1986-88 FC factory manual specifies 4-5 notches with a 22 lb pull. The 1993 FD data specifies 7-10 notches with a 44 lb pull. Check the spec for your year.

Why will my RX-7 rear caliper piston not push back in?

The rear piston is threaded onto the parking brake adjuster, so it has to be rotated clockwise while pressed in. Mazda uses the disc brake piston wrench 49 FA18 602 for this.

Can I fix a weak parking brake just by tightening the cable?

Only if the calipers are healthy. If a caliper lever does not return to its stopper pin or the adjuster has seized, tightening the cable will make the brakes drag without fixing the cause.

Why does my rear brake drag after adjusting the parking brake?

The cable is too tight. On the FC, the lever-to-stopper-pin clearance at the caliper should be under 2 mm. Back the adjust nut off and spin both wheels to confirm they turn freely.

What brake fluid does an RX-7 use?

The FC factory manual lists FMVSS 116 DOT-3 or DOT-4. The 1993 Mitchell procedure specifies DOT 3 and warns against mixing types. Follow the marking on your reservoir cap.

Sources

1. Mazda 1986-88 RX-7 Factory Service Manual, Section 11 Braking System - parking brake type, 4-5 notch stroke, 2 mm stopper clearance, piston wrench, lock bolt torque, fluid spec
2. 1993 Mazda RX-7 Brakes, Mitchell Repair Information - 7-10 notch stroke, rear pad and rotor limits, caliper removal steps, DOT 3
3. Brake and Front End: Adjusting Parking Brakes - screw-type caliper adjustment order, knocking with no cable tension, console-mounted adjuster