2004-2012 Aston Martin DB9 Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most 2004-2012 Aston Martin DB9 caliper problems come down to a sticking piston in one of the four-piston Brembo calipers, a leaking piston seal, or a worn rear handbrake caliper, not a caliper that has cracked or failed outright. The telltale sign is uneven pad wear: if the inner and outer pads on one wheel are wearing at different rates, a piston is not moving freely. In many cases the fix is a caliper reseal or a replacement caliper, plus fresh pads, wear sensors and new caliper bolts.

How the DB9 Brake Calipers Work

The DB9's brake system was designed by Brembo. Each standard steel-brake car uses a four-piston Brembo caliper at every corner. The fronts clamp a one-piece 355 mm x 32 mm rotor and use two piston sizes, 40 mm and 44 mm, so the pad is pressed evenly along its length. The rears are smaller four-piston calipers working on a one-piece 330 mm x 28 mm rotor. Because these are fixed, opposed-piston calipers, the pistons on both sides of the rotor do the work. There are no sliding pins to seize the way there are on a typical economy-car caliper, so when a DB9 caliper sticks, it is almost always a piston or seal problem.

The rear axle has a second, separate caliper at each wheel. This small handbrake caliper has a single piston, is operated by cable from the handbrake lever, and has its own pads. It does nothing when you press the pedal. It only holds the car when parked.

Some DB9s were ordered with the optional carbon ceramic brakes. Everything below applies to the standard steel-rotor system. Carbon ceramic cars use different parts and service rules, so confirm which system your car has before ordering anything.

Symptoms of a DB9 Caliper Problem

• Uneven pad wear. The inner and outer pads on one wheel should wear at about the same rate. If one is clearly thinner, suspect a seized piston or a blocked fluid passage inside the caliper.
• Pulling to one side under braking. One caliper is applying harder or releasing slower than the other.
• Dragging or a hot wheel. A piston that does not retract keeps the pad on the rotor. You may smell hot brakes after a drive, feel the car coasting less freely, or see heavier dust on one wheel.
• Fluid at the caliper. Wet fluid around the pistons or on the inside of the wheel means a seal is leaking. Treat that as urgent.
• Torn piston boots. The rubber dust boots should be dusty but intact. A split boot lets water and grit in, which is how pistons start to corrode and stick.
• Weak handbrake. A healthy DB9 handbrake should click about four times at full application and hold the car securely. More travel, or a car that creeps, points to worn handbrake pads or a sticking handbrake caliper.
• Glazed or cracked rotors. A dragging caliper overheats the rotor. Glazing, heat cracks, or runout above about 70 micrometers (0.0027 in) are all signs of heat damage.

What Causes DB9 Calipers to Stick or Leak

The main cause is age and moisture. Brake fluid is hygroscopic: it slowly absorbs water from the air through the porosity of the brake lines. That water lowers the fluid's boiling point and corrodes metal parts from the inside. Inside a caliper, corrosion builds up behind the piston seals until a piston will not return. A DB9 that sits for long periods, as many of these cars do, is especially prone to this, because the pistons do not move enough to stay clean.

The second cause is a damaged dust boot. Once dirt and road salt get past it, the exposed piston surface pits, and a pitted piston will tear its seal and leak. Heat from hard driving also ages seals faster. Brembo recommends replacing brake fluid every 2 to 3 years. On a low-mileage DB9, go by time, not miles, and use the fluid specified in the owner's handbook.

The Fix: Reseal, Replace, or Just Service?

Start by pulling the pads and looking at how they wore. If they are even and the pistons push back smoothly with no leaks or torn boots, the caliper is fine. Clean it, fit new pads, and move on.

If one or more pistons are stiff, or a seal is leaking, you have two options:

1. Reseal the caliper. New seals and boots, with the pistons cleaned or replaced. This works when the piston surfaces and bores are smooth. It is careful bench work: every piston has to come out, and the caliper must be kept perfectly clean.
2. Replace the caliper. This is the right call if a bore or piston is pitted, the caliper body is badly corroded, or you do not want the car off the road while calipers are rebuilt. Note that front calipers are side-specific, so order the correct left and right.

Whichever route you choose, work in axle pairs. Replacing both front or both rear calipers together keeps braking balanced side to side, since both calipers are the same age and have worked just as hard. Browse our brake calipers and brake hardware kits for what you need.

What to Replace at the Same Time

• Brake pads. A dragging caliper usually ruins its pads, and you should never refit contaminated pads to a rebuilt caliper. For the DB9 we carry the EBC Redstuff ceramic front brake pads for the 2004-2012 DB9 and matching EBC Redstuff ceramic rear pads. These are low-dust street pads, which matters on a DB9 because the original-equipment pads are known for heavy dust. If you drive hard or do track days, look at the EBC Yellowstuff street and track front pads and Yellowstuff rear pads.
• Wear sensors. The DB9 has a sensor on the inner pad at all four wheels. They are made to be replaced whenever the pads are changed.
• Caliper mounting bolts. The DB9's M12 caliper bolts are torque-to-yield and single-use. A full four-caliper job needs eight new bolts. Tighten them to the factory service manual procedure.
• Rotors, if they are under spec. Measure them. Front rotors are done at 30 mm and rears at 26 mm. Replace any rotor that is cracked, glazed, or out of runout spec. See our brake rotors.
• Brake fluid. Opening a caliper means bleeding the system anyway, so flush the whole system with fresh fluid.
• Handbrake pads. While the rear wheels are off, check the separate handbrake pads. Plan to replace them if they are down to about 2 mm.

How Hard Is the Job?

A pad change on a DB9 is a manageable job for a skilled DIYer with good jack points, a torque wrench and new hardware. Caliper work is a step up. You need to open the hydraulic system, fit the new single-use bolts properly, route the wear-sensor wiring through its clips (the fronts use fir-tree zip-tie mounts that often break when removed), and bleed the brakes until there is no air left. The rear handbrake calipers and their cable adjustment add more work at the back. If you are not comfortable bleeding brakes and checking that the pedal is firm, have the caliper stage done by a shop that knows these cars. You can still supply your own pads and hardware from our brake pads range.

Frequently Asked Questions

Do DB9 brake calipers have slide pins that need greasing?

No. The main DB9 calipers are fixed, four-piston Brembo units, so there are no sliding pins. Sticking is caused by the pistons and seals, which is why pad wear on the inner and outer pads tells you so much.

Can I rebuild my DB9 calipers instead of replacing them?

Yes, if the bores and pistons are smooth and free of pitting. A reseal with new seals and boots restores a sticking caliper. If the pistons or bores are pitted, replace the caliper or its pistons, because new seals will not hold against a damaged surface.

Why does only one rear wheel on my DB9 get hot?

Check both rear calipers. It could be a sticking piston in the main four-piston caliper, or the separate cable-operated handbrake caliper on that side not releasing fully. Both keep a pad pressed against the rotor.

Do I need new wear sensors with new pads on a DB9?

Yes. The sensors sit on the inner pad at each wheel and trigger the dash warning when the pad wears to about 2.5 mm. Once one has triggered, it has done its job and needs to be replaced. Fitting new sensors with every pad change is standard practice.

Can I reuse the caliper bolts?

No. The DB9 caliper mounting bolts are a torque-to-yield design meant for one use only. Buy eight new bolts for a full job and tighten them following the factory service manual.

Do these parts fit a DB9 with carbon ceramic brakes?

No. The pads and rotor specs in this guide are for the standard steel-rotor system. Carbon ceramic cars use different parts, so confirm which system your car has before ordering.

Sources

1. Aston 1936 - Inspecting the brakes in an Aston Martin DB9 or Vantage - four pistons per caliper, pad and rotor new/minimum thickness, 70 micrometer runout, wear sensors, handbrake caliper and four-click check
2. Aston 1936 - Parts needed for a full brake service of a DB9 - Brembo-designed system, torque-to-yield M12 caliper bolts (eight per car), wear sensors, fir-tree mounts, dusty OE pads
3. Aston 1936 - Brake rotor options for the DB9 - 355 x 32 mm front and 330 x 28 mm rear rotors, four-piston calipers, carbon ceramic option
4. Vagbremtechnic - DB9 front Brembo 4-piston calipers - 40 mm and 44 mm front piston sizes, side-specific caliper orientation
5. Brembo - Brake fluid for cars - fluid absorbs moisture, lower boiling point, 2 to 3 year replacement recommendation
6. Power Stop - When should I replace brake calipers - caliper failure symptoms, seized pistons, replacing calipers in pairs