Parking Brake Adjustment on Rear Disc Brakes

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a car with rear disc brakes, the parking brake is adjusted in two stages: first the braking element itself (the small shoes inside the rotor hat, or the self-adjusting mechanism inside the caliper), then the cable. Tightening the cable alone to take up slack is the most common mistake, and it usually leaves the rear brakes dragging. Electronic parking brakes are the exception: they set their own clearance and need a scan tool, not a wrench.

Three Parking Brake Designs Used With Rear Discs

Before you touch an adjuster, identify which system your vehicle has. The procedure for one will misadjust or damage the others.

A quick look behind the wheel usually settles it. If the parking brake cable ends at a lever on the caliper body, you have an integral caliper. If the cable disappears through the backing plate behind the rotor and the rotor has a rubber access plug, you have drum-in-hat shoes. If there is a wiring connector on the caliper and a switch instead of a lever or pedal in the cabin, it is an EPB. According to one EPB service guide, the motor-on-caliper layout is the most common electronic design, while a smaller number of vehicles use a single motor that pulls cables.

Symptoms That Mean the Parking Brake Needs Attention

• Too much lever or pedal travel. Factory manuals give a travel spec. The 2008 Nissan Maxima, for example, calls for 7 to 8 notches of lever stroke under a pull of 196 N (44 lb-f). Travel well past your vehicle's spec means the shoes or cable need adjustment.
• The car creeps on a slope with the parking brake fully set.
• Drag, heat or a hot-brake smell after release. This points to shoes set too tight, a cable that is too tight, or a lever that is not returning to its stop.
• A low brake pedal on integral calipers. Rustic Disc Brakes notes that if these calipers will not adjust, the piston retracts too far and uses up hydraulic pedal travel, so the pedal sits low.
• Weak holding after new shoes or rotors. New linings need a break-in before they hold at full strength (covered below).

To diagnose, raise the rear of the vehicle safely, release the parking brake, and spin each rear wheel by hand. Listen and feel for drag. Then apply the parking brake and count the clicks or measure the pedal travel against the figure in your owner's or service manual.

How to Adjust Drum-in-Hat Parking Brake Shoes

The Nissan factory service manual for the 2008 Maxima lays out a clear sequence that matches how most drum-in-hat systems are set up. Always use the exact figures from the manual for your own vehicle.

1. Fully release the parking brake and slacken the cable. Nissan has you loosen the cable adjusting nut first, so cable tension cannot hold the shoes apart while you set them.
2. Remove the adjuster hole plug in the rotor and line the hole up with the star wheel.
3. Expand the shoes until the rotor locks. Turn the star wheel with a screwdriver or brake spoon until the rotor cannot be turned by hand.
4. Back the adjuster off. Nissan specifies 5 or 6 notches in the opposite direction for that car. Wilwood's instructions for its internal parking brake say to back off just enough that the drum can be rotated, and note that some slight drag is fine.
5. Spin the rotor to confirm there is no heavy drag, then reinstall the plug.
6. Now adjust the cable. Nissan has you press the brake pedal fully more than five times, confirm no drag at the rear wheels, cycle the lever through its full stroke 10 or more times, then turn the adjusting nut until the lever stroke meets spec.
7. Recheck for drag with the brake released. If drag remains, Nissan directs you to pull the rotor and verify the toggle lever returns to its stopper; if it does not, loosen the cable nut and set the shoe clearance again.

A few details trip people up. On the Maxima the adjuster is oriented differently on the left and right sides, so the direction that expands the shoes is not the same on both wheels. Nissan also warns not to reuse the cable adjusting nut after removal. Wilwood cautions against working the parking brake lever while the drum is off.

Integral Caliper Parking Brakes

On rear calipers with a built-in mechanical parking brake, the lever on the caliper does double duty: it applies the pads for parking and it drives the internal adjuster that moves the piston out as the pads wear. Rustic Disc Brakes, which builds rear caliper conversions, gives a straightforward setup method for its calipers:

1. Disconnect the parking brake cables and remove the lever return springs.
2. Push each caliper lever all the way forward and back rapidly to ratchet the adjuster out.
3. Check the result: once adjusted, the lever should move off its stop only about 3/8 to 1/2 inch before the pads clamp.
4. Reinstall the springs and cables, and set cable tension so the levers still rest against their stops when the parking brake is released.

The same instructions give a simple check: grab the brake pad and try to shake it. If it rattles, the lever needs more adjustment. They also warn that failing to adjust the levers before applying the hydraulic brakes can leave you with no parking brake and premature brake wear. Procedures differ between caliper makers, so check your service manual for the exact method, and for how the piston is retracted during a pad job before you force it back.

A lever the cable holds off its stop keeps the pads lightly applied and overheats the rotor. If a caliper will not adjust at all after cycling, the internal mechanism has usually failed, and replacement rear brake calipers are the fix.

Electronic Parking Brakes: Use Service Mode, Not Force

An EPB has no star wheel or cable nut to adjust. On motor-on-caliper systems, the piston is driven by a self-locking gear, so it cannot simply be pushed back. The EPB service guide cited below warns that forcing the piston without entering service mode is likely to strip the internal gear mechanism. Service mode, entered through a scan tool or the vehicle's own menus, retracts the pistons fully and disables the system while you work. When you exit service mode, the system advances the pistons and sets running clearance on its own.

If the caliper will not release or retract in service mode, stop and follow the manufacturer's release procedure for a stuck caliper or failed motor rather than prying on the piston.

Break-In After New Shoes, Pads or Rotors

New drum-in-hat shoes do not hold at full strength until they seat against the drum. Nissan's procedure for the 2008 Maxima is specific:

1. Drive the unloaded vehicle on a safe, level, dry road.
2. Pull the lever with a force of 147 N (33 lb-f) and, while holding it, drive forward 100 meters (328 ft) at about 35 km/h (22 mph).
3. Let the parking brake cool for about five minutes, then release it and drive normally for two minutes.
4. Repeat the cycle three times, then recheck lever stroke and adjust again if it is out of spec.

Nissan cautions that overdoing the break-in can cause uneven or premature lining wear. Follow your own vehicle's procedure where one is published. For new service pads and shoes, Wagner recommends about 20 complete stops from 30 mph, or 20 slow-downs from 50 mph to 20 mph with light to moderate pedal pressure, no panic stops, and at least 30 seconds between applications to cool.

What to Inspect and Replace at the Same Time

Adjustment cannot fix worn or seized parts. While the rotor is off, check these:

• Shoe lining thickness. On the 2008 Maxima the lining is 3.2 mm (0.126 in) new with a wear limit of 1.5 mm (0.059 in). Replace parking brake shoes as a set when either side is at the limit, or if the lining is peeling or contaminated.
• Drum diameter inside the rotor hat. Nissan lists 172.0 mm (6.77 in) new and 173.0 mm (6.81 in) maximum for that car. The drum is part of the rotor, so a hat worn past its limit means new brake rotors.
• Springs and adjuster. Nissan's inspection list includes return springs for sagging, the adjuster for rough operation, and the anchor pin for wear and corrosion. Clean the adjuster, apply brake grease to its threads and the contact points, and replace tired springs with a brake hardware kit.
• Cables. A frayed, kinked or corroded cable that will not return freely will undo any adjustment.

Most drum-in-hat and integral-caliper adjustments are a moderate driveway job with basic hand tools, jack stands and the factory manual. Budget more time for shoe replacement, since the small return springs are fiddly. EPB work is simple mechanically but requires a scan tool that supports your vehicle's service mode. If the rear pads are due at the same time, see our brake pads.

Frequently Asked Questions

Can I adjust the parking brake by just tightening the cable?

Not correctly. On drum-in-hat systems the shoe clearance has to be set first; tightening the cable to make up for loose shoes can hold the shoes partly applied and cause drag. Factory procedures loosen the cable, set the shoes, and only then set the cable.

How many clicks should my parking brake take?

It depends on the vehicle, and the spec is usually given at a specific pull force. The 2008 Nissan Maxima, for example, calls for 7 to 8 notches at 196 N. Check your owner's or service manual for your own number.

Why does my rear brake pedal feel soft on a car with integral parking brake calipers?

When the adjuster inside the caliper is not keeping up, the piston retracts too far and uses up pedal travel before the pads reach the rotor. Cycling the caliper lever per the manufacturer's procedure often restores it; a caliper that will not adjust needs to be replaced.

Do electronic parking brakes need adjustment?

Not by hand. The system sets its own clearance when it exits service mode. You do need a scan tool or the vehicle's service menu to retract the pistons before a pad job.

Should I replace parking brake shoes when I replace rear rotors?

Not automatically, but inspect them. If the lining is at or near the manufacturer's wear limit, contaminated, or glazed, replace them while the rotor is off, then adjust and break them in.

Sources

1. Nissan 2008 Maxima Factory Service Manual, Section PB Parking Brake System - shoe clearance and cable adjustment sequence, lever stroke spec, break-in procedure, lining and drum wear limits
2. Rustic Disc Brakes: Rear Caliper Parking Brake Lever Adjustment - lever cycling method, 3/8 to 1/2 inch lever travel, pad rattle check, low pedal when calipers will not adjust
3. Wilwood: How to Adjust the Internal Parking Brake - star wheel lock-and-back-off method, slight drag acceptable, do not actuate lever with drum off
4. Wagner Brake: Disc Pad and Brake Shoe Break-In Procedure - burnish stops, speeds and cooling interval
5. Electronic Parking Brake: How It Works and How to Service It - EPB designs, service mode, risk of forcing the piston