2002-2006 Infiniti Q45 Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

The most common caliper problems on a 2002-2006 Infiniti Q45 are sticking pistons and seized slide pins, which show up as a pull to one side, a hot wheel, a burning smell and one pad worn far thinner than its partner. A leaking piston seal is less common but more serious. On a car this age the usual fix is a remanufactured or new caliper, fresh pads, and a flush and bleed, and the floating caliper design makes it a manageable job for a careful home mechanic.

How the Q45 caliper setup works

The third-generation Q45 (the 2002-2006 rear-wheel-drive V8 sedan) uses disc brakes at all four corners. Its calipers are shared with the 2003-2004 Infiniti M45, which is useful to know when you shop: Cardone lists its remanufactured caliper 19-2790 for both the Q45 2002-2006 and the M45 2003-2004.

That Cardone unit is a floating caliper with a single steel piston of 1.682 in (42.7 mm) diameter, a banjo-type hose inlet and an M7x1.0 bleeder. A floating caliper has its piston on one side only. When you press the pedal, the piston pushes the inner pad into the rotor, and the caliper body slides inward on two guide pins to pull the outer pad into the other face. That sliding motion is the weak point as the car ages: if the pins corrode or their grease dries out, the caliper cannot center itself and one pad does most of the work.

Because these cars are now roughly two decades old, most surviving Q45s have original or long-serviced calipers, rubber hoses that have seen many heat cycles, and brake fluid that may not have been changed on schedule. Those three things together explain most of the caliper trouble owners run into.

Symptoms of a failing caliper

• Pull under braking. A caliper that applies weakly or late on one side makes the car dart toward the side that is still working.
• Drag and heat after a drive. A stuck piston or seized pin keeps the pad on the rotor. That wheel is noticeably hotter than the others, the rim may be coated in dark brake dust, and you may smell hot brakes.
• Uneven pad wear. Inner pad down to the backing plate while the outer pad still has plenty of material is the classic sign of a seized slide pin.
• Soft or sinking pedal and fluid on the tire. Wet residue on the inside of the wheel or around the piston boot means the seal is leaking. Stop driving the car until it is fixed.
• Clunk or rattle over bumps. Worn or missing abutment clips let pads shift in the bracket.
• A sluggish feel and worse fuel economy. Constant drag robs power even when you are not braking.

PowerStop's caliper guide lists the same warning signs: brakes that feel constantly engaged, pulling to one side from seizing pistons, abnormal noise, extra pedal effort, and fluid leaks from worn seals.

How to diagnose it before buying parts

1. After a normal drive, carefully compare wheel temperatures by holding your hand near (not on) each hub. One clearly hotter wheel points to that caliper.
2. Lift the car safely and spin each wheel by hand in neutral. A wheel should turn with light drag; one that stops almost immediately is binding.
3. Pull the wheel and measure both pads. A large difference between inner and outer points to the slide pins; heavy wear on both pads of one caliper points to a sticking piston.
4. Remove the caliper and try the slide pins. They should move in and out by hand with light resistance. If they are frozen or the boots are torn, that is your problem.
5. Inspect the piston boot and the flexible hose. A cracked boot lets water rust the piston. A hose that has collapsed internally can act like a check valve and hold pressure on the caliper, which mimics a stuck piston, so check it before condemning the caliper.

Infiniti's maintenance schedule for the 2004 Q45 calls for inspecting the brake pads and rotors every 15,000 miles or 12 months under standard conditions, and every 7,500 miles or 6 months under severe conditions. A caliper that is starting to stick is usually caught at one of those checks by uneven pad wear.

Common causes on this car

Rebuilding with a seal kit is possible, but once the piston itself is pitted a rebuild will not last. For most owners a remanufactured or new caliper from our brake calipers collection is the faster and more reliable route. Unloaded remanufactured units come without pads, so plan on pads at the same time.

What to replace at the same time

• Pads on both sides of the axle. A dragging caliper usually cooks its pads, and pads should always be replaced in axle sets so braking stays even. See our brake pads and ceramic brake pads.
• Rotors if they are blued, scored or below minimum thickness. Heat from a stuck caliper often distorts or glazes the rotor. We carry Q45 fitments such as these front drilled and slotted rotors for the 2002-2006 Q45, plus standard options in brake rotors.
• Hardware. New abutment clips and guide pin boots from a brake hardware kit cost little and help prevent the next seizure.
• Sealing washers at the banjo fitting. The Q45 caliper uses a banjo inlet, and PowerStop notes the hose-to-caliper crush washer should be replaced to prevent leaks.
• The flexible hose if it is cracked, swollen or original.

Replacing calipers in pairs across an axle is a sensible choice on a car this old. If one has seized, the other has lived the same life.

How hard is the job?

Caliper replacement on the Q45 is a moderate job for someone who has already changed pads. The basic steps are:

1. Loosen the lugs, lift the car on a lift or on jack stands on solid ground, and remove the wheel.
2. Clamp or plug the hose to limit fluid loss, then remove the banjo bolt and the caliper mounting bolts.
3. Clean the bracket with brake cleaner and a brass brush, as PowerStop recommends, and grease the guide pins and clip contact points with high-temperature caliper grease.
4. Install the new caliper with new crush washers, torque every bolt to the value in the factory service manual, and install pads and hardware.
5. Bleed the brakes following the service manual sequence until the fluid runs clear with no bubbles. A caliper swap opens the system, so a full flush is a smart add-on.
6. Pump the pedal before moving the car, then bed in the new pads with a series of moderate stops.

Two cautions: never let the caliper hang by its hose, and never drive until the pedal is firm and high. Keep the master cylinder reservoir topped up during the bleed; letting it run dry pulls air deeper into the system and makes the job much harder.

Related recall worth checking

There is no caliper recall on these years, but NHTSA recall 04V497000 covers certain 2004 Q45s whose brake lamp switch may malfunction so the brake lights do not come on when you press the pedal. Dealers replace the switch. If you are working on the brakes of a 2004, run the VIN through NHTSA or Infiniti to confirm it was done.

Frequently Asked Questions

Are the 2002-2006 Q45 calipers the same as the M45?

The 2003-2004 M45 shares calipers with the 2002-2006 Q45; Cardone lists its remanufactured caliper 19-2790 for both. Always confirm the position (front or rear, left or right) on the part listing before ordering.

Can I replace just one caliper?

You can, and it will cure the immediate problem, but on a car this age the caliper on the other side of the axle has had the same exposure. Replacing both keeps braking balanced.

Do I need to bleed the whole system after a caliper swap?

At minimum bleed the corner you opened. Because the fluid in many Q45s is overdue, most techs flush the whole system at the same time with the fluid grade shown on the reservoir cap.

Why does my Q45 pull to one side only when braking?

A braking pull usually means the caliper on the opposite side is not applying fully, often from a stuck piston or seized pins, though a collapsed hose or contaminated pads can do the same.

Is a remanufactured caliper as good as new?

A quality remanufactured caliper is rebuilt with new seals and tested, and it is a common, reliable repair. Check that it matches your side and comes with the correct bleeder.

Sources

1. Cardone - Disc Brake Caliper 19-2790 - Q45 2002-2006 and M45 2003-2004 fitment, floating design, single 1.682 in steel piston, banjo inlet, M7x1.0 bleeder
2. NHTSA - 2004 Infiniti Q45 recalls - recall 04V497000, brake lamp switch
3. Infiniti USA - 2004 Q45 brake pads and rotors maintenance schedule - inspection intervals
4. PowerStop - Helpful tips for installing a new brake caliper - failure symptoms, bracket cleaning, crush washers, bleeding