2004-2012 Aston Martin DB9 Parking Brake Problems and Adjustment

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2004-2012 Aston Martin DB9 does not use a drum-in-hat parking brake or an electric one. It uses a separate, cable-operated mechanical caliper on each rear disc, pulled by a lever beside the driver's seat. Most DB9 parking brake complaints - a lever that pulls up too far, a warning light that stays on, a squeal or drag from the rear, or a car that creeps on a hill - come down to cable adjustment, a sticking hand brake caliper, or a rear disc that has been damaged by pads that never fully release.

How the DB9 Parking Brake Works

According to the factory workshop manual (section 06.05, Hand Brake), the control lever sits at the outer side of the driver's seat. Pulling it tensions a cable that applies a small mechanical caliper at each rear wheel. Each of those calipers clamps its own pair of pads against the same ventilated rear disc that the main four-piston rear caliper uses, and each caliper is bolted to the rear vertical link.

Three details matter for diagnosis:

• Self-adjusting calipers. The manual states the hand brake calipers have a mechanism that automatically adjusts for pad wear. The cable adjusters are there to take up cable stretch, not pad wear.
• Warning switch on the lever. A switch in the lever assembly closes when the brake is applied and turns on the brake warning light. When the lever is fully down, the light should be off.
• Separate pads, separate job. The hand brake pads are not part of the service brake pad set. An independent Aston Martin specialist notes these small pads may last the life of the car, because they mostly hold the car when parked.

Because the parking brake shares the rear disc with the service brakes, anything that goes wrong with one can show up on the other. A hand brake caliper that drags will heat and groove the disc your main rear pads ride on.

Common DB9 Parking Brake Problems and Symptoms

The squeal and groove problems are the ones DB9 owners run into most often. The workshop manual's adjustment check specifically says that if the pads touch the discs and squeal, the adjusters must be loosened. Over-tightening the cable to get a firmer lever is the usual way it starts: the small pads never fully back off, the rear discs run hot, and eventually a ring is cut into the disc face.

How to Adjust the DB9 Parking Brake

The factory procedure is short. It adjusts both calipers equally so the car does not pull to one side when the lever is used:

1. Raise the rear of the car safely on stands and make sure the hand brake lever is fully released.
2. At each rear caliper, release the cable lock nuts and turn the adjustment fully in.
3. Turn the adjustment out or in on each caliper by an equal amount until the lever gives 4 clicks when you operate it.
4. Tighten the lock nuts.
5. With the lever fully down, confirm the brake warning light is off, and that both rear wheels turn freely by hand.
6. If you hear the pads touching the discs, loosen the adjusters and re-check.

If you cannot get 4 clicks without the rear wheels dragging, the cable is not the problem. Look at the caliper itself: an actuator arm that does not return, corrosion, or a failed self-adjuster will not be fixed by cable tension.

Replacing a Hand Brake Caliper or Its Pads

When a hand brake caliper is seized, or its pads are worn or oil-contaminated, the caliper comes off the vertical link. The factory removal sequence is:

• Raise the car, remove the rear wheel, and release cable tension by turning the adjusters on both calipers.
• Unhook the cable eyelet from the caliper actuator arm and release the outer cable from its bracket (the manual calls for a specific service tool for this).
• Remove the two caliper bolts and discard them - they are not reused.
• Clean the parts with a vacuum brush or aqueous brake cleaner. The manual warns against blowing brake dust off with compressed air.

On installation, hand brake pads are renewed in axle sets. The hand brake section lists a minimum lining thickness of 6 mm for these pads, far thicker than the 2.5 mm minimum for the main pads, so do not judge them by the same eye. New caliper bolts are torqued to 15 Nm and then turned a further angle (the hand brake section gives 92 degrees; the disc brake section gives 90 to 94 degrees). After fitting, the manual says to work the caliper lever by hand at least three times to close up the gaps between pistons, pads and disc, then adjust the cable as above.

Rear disc replacement on a DB9 also requires removing the hand brake caliper first, so if your rear discs are grooved, it makes sense to inspect or renew the hand brake pads during the same job.

What to Replace at the Same Time

The rear discs are where parking brake trouble shows up. Per the workshop manual, DB9 rear discs start at 28.0 mm and are at their limit at 26.0 mm; front discs start at 32 mm with a 30 mm minimum. A disc with a deep hand brake groove or below minimum should be replaced, and service pads should always go on fresh or properly resurfaced discs. Browse brake rotors and the wider brake parts catalog for the rest of the job.

If the rear service pads are near their limit while you are in there, do them at the same time. For the DB9 we carry the EBC Redstuff ceramic rear brake pads (DP31909C) for quiet, low-dust road use, and the EBC Yellowstuff rear brake pads (DP41909R) for owners who drive hard or do track days. Matching fronts are the EBC Redstuff front pads (DP31908C) and EBC Yellowstuff front pads (DP41908R). More options are in our ceramic brake pads collection. Remember that these are service brake pads; the small hand brake pads are a separate part.

Any time a hydraulic caliper is opened on the way to the hand brake, bleed with the fluid the manual specifies: a DOT 4 fluid, and never a silicone-based fluid.

Always Use the Parking Brake on Later Automatic DB9s

There is a second reason to keep this system in good order. NHTSA campaign 17V-796 covers 2009-2016 DB9 models with the 6-speed Touchtronic II automatic. A communication error between the engine and transmission control modules can stop the transmission park pawl from engaging. NHTSA's recall notice says that if this happens on a slope and the driver exits without applying the parking brake, the car may roll. The remedy is a free transmission control module software update at an Aston Martin dealer, so check your VIN on nhtsa.gov. Whether or not your car has had the update, a correctly adjusted parking brake is what holds the car if the park pawl does not.

How hard is this job? Adjusting the cable is straightforward for a home mechanic with stands. Replacing a hand brake caliper is moderate: the one-time-use bolts, angle torque, and cable service tool mean a torque wrench, an angle gauge and patience. If the service calipers or disc also need attention, plan it as a full rear brake job.

Frequently Asked Questions

Does the Aston Martin DB9 have an electric parking brake?

No. The 2004-2012 DB9 uses a manual lever at the outer side of the driver's seat, connected by cable to a mechanical caliper at each rear wheel.

How many clicks should the DB9 hand brake lever have?

The factory adjustment procedure targets 4 clicks of the lever, with the cable adjusted equally at each rear caliper.

Why does my DB9 squeal from the rear after adjusting the hand brake?

The cable is almost always too tight, so the hand brake pads are touching the disc. The manual says to loosen the adjusters if the pads contact the discs. Left alone, this grooves the rear discs.

Do I need to replace the hand brake pads when I do rear brakes?

Not automatically. They are separate from the service pads and wear slowly. Inspect them whenever the hand brake caliper comes off for a rear disc change, and replace them in axle sets if they are below 6 mm, contaminated, or damaged.

Why is my brake warning light on with the hand brake released?

The lever switch turns the light on when the brake is applied. If it stays on with the lever fully down, the lever may not be fully released or the cable needs adjusting. Also check brake fluid level, since the same light can warn of other brake faults.

Is there a parking brake recall on the DB9?

Not on the parking brake itself. Recall 17V-796 affects the park pawl on 2009-2016 DB9s with the Touchtronic II automatic, which makes using the parking brake every time you park especially important until the software update is done.

Sources

1. Aston Martin DB9 Workshop Manual, Hand Brake (06.05) description - lever location, cable, mechanical calipers, self-adjusters, warning switch
2. Aston Martin DB9 Workshop Manual, Hand Brake specifications and removal - 6 mm minimum lining, 15 Nm plus 92 degrees, discard bolts, operate lever three times
3. Aston Martin DB9 Workshop Manual, Hand Brake adjustment - 4-click adjustment, warning light check, loosen if pads squeal
4. Aston Martin DB9 Workshop Manual, Section 6 Brake System (PDF) - disc thickness limits, DOT 4 fluid, hand brake caliper torque, rear disc removal order
5. Aston1936 - Servicing the brakes on an Aston Martin DB9 or Vantage - separate self-adjusting hand brake calipers, pads can last the life of the car
6. NHTSA Recall 17V-796 acknowledgement - 2009-2016 DB9 park pawl may not engage, TCM software remedy