2005 Volvo S40 Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

The most common caliper problems on a 2005 Volvo S40 are a sticking or seized caliper that drags, a leaking piston seal, and a rear caliper piston that will not retract during a pad change. A dragging caliper shows up as a pull to one side, a hot or smoking wheel, a burning smell, and one pad worn far thinner than its partner. The fix is usually a replacement caliper, fresh pads, and a proper bleed, and on the rear axle the piston has to be wound back, not pushed.

How the Calipers Work on the 2005 S40

The 2005 S40 has disc brakes at all four wheels. When you press the pedal, hydraulic pressure pushes a piston out of each caliper, which clamps the pads against the rotor. The caliper body floats on guide pins so both the inner and outer pad share the load. When the pedal is released, the piston seal pulls the piston back slightly and the pads stop pressing on the rotor.

The rear calipers do a second job. Volvo's owner's manual for the 2005 S40 states that the parking brake lever sits between the front seats and that the parking brake is applied to the rear wheels. On this car the handbrake cable runs to a lever on the back of each rear caliper, and an internal screw mechanism pushes the piston out mechanically. That design has two consequences you need to know before you pick up a wrench:

• The rear piston cannot be pushed straight back into the bore. It has to be rotated while it is pressed in, because the screw mechanism only lets it travel in a spiral. Volvo's own procedure calls for a press tool used together with a spanner that engages the piston face.
• The screw mechanism is also the self-adjuster. If the parking brake is rarely used, the adjuster does not get exercised, and Brake and Front End notes that excessive service brake pedal travel can result.

Symptoms of a Bad Caliper

Caliper trouble tends to show up one wheel at a time, which is the biggest clue that the caliper, not the pads, is the problem. The Motorist Assurance Program lists the signs technicians look for, and they line up with what shows up on older S40s:

A quick check: after a normal drive with no hard stops, carefully hold the back of your hand near each wheel without touching the rotor. A corner that is noticeably hotter than its partner on the same axle is dragging. Then lift that corner and spin the wheel by hand with the car in neutral. Some light pad contact is normal; a wheel that stops after half a turn is not.

If the BRAKE and ABS warning lights come on together, the owner's manual says this could indicate a fault in the brake system. If the fluid is below the MIN mark or the display shows "Brake failure - Service urgent," Volvo says not to drive the car. A leaking caliper can drop the reservoir level enough to trigger that warning.

Why S40 Calipers Stick

A 2005 S40 has many winters behind it by now, and caliper failure is almost always a corrosion story.

• Torn dust boots. Brake and Front End explains that when a defective boot lets moisture get between the bore and the piston, the piston will eventually corrode and seize. A split boot means a caliper that is already on its way out.
• Dry or rusted guide pins. The caliper has to slide freely. Pins that have lost their grease bind, and the inner pad ends up doing most of the work. The same trade article notes a seized floating caliper may wear the inboard pad more than the outboard pad.
• Old brake fluid. Brake fluid absorbs water over time. That water corrodes the bore from the inside, which is why a caliper can seize even with an intact boot.
• A neglected parking brake. On the rear, the screw mechanism and the lever on the back of the caliper can rust in place if the handbrake is rarely used, leaving the rear pads lightly applied all the time or leaving the handbrake weak.

The Fix: Which Part You Need

For a dragging or leaking caliper, the practical repair today is a replacement caliper rather than a rebuild. Brake and Front End notes that shops are not likely to rebuild disc brake calipers anymore, and that if a bleeder screw is seized, it is probably cheaper to replace the caliper. A remanufactured unit arrives pressure tested with a new piston seal and boot. Browse our brake calipers for sale or the Cardone remanufactured caliper line, and confirm the position (front or rear, left or right) before ordering, because the rear calipers are handed and carry the parking brake lever.

What to know by axle:

• Front: the simpler job. Remove the guide pin bolts, lift the caliper off, disconnect the brake hose at the caliper, install the new caliper, then bleed.
• Rear: the parking brake cable must be released from the lever on the caliper before the caliper comes off, and it must be reconnected and checked afterward. Brake and Front End notes that on screw-type calipers the piston is turned fully to the bottom of the bore to set the correct position for cable adjustment, and the handle should have immediate tension when pulled. A cable with no tension can cause a knocking noise over bumps.

Replace calipers in pairs on the same axle when both are the same age and one has failed. The other side has seen the same water, heat and salt, and a new caliper on one side with an old one on the other invites a pull.

What to Replace at the Same Time

A seized caliper damages what it touches. Plan on these while the wheel is off:

• Pads. Pads that ran against a dragging caliper are usually glazed or tapered. Fit a new set on both sides of the axle. We carry pads for this car, including the Hawk HPS 5.0 rear brake pad set for the 2005 Volvo S40, plus the full range of replacement brake pads.
• Rotors. Heat from a dragging pad often leaves blue spots, hard spots or a lip. If the rotor is below the minimum thickness stamped on it or shows hot spots, replace it. See our brake rotors.
• Hardware. New clips and properly greased guide pins keep the new caliper sliding. A brake hardware kit is inexpensive insurance.
• Flexible hose. If the hose is cracked, swollen, or its fitting is rusted to the caliper, replace it now. Our brake hoses collection covers this.
• Brake fluid. Bleeding a new caliper is a good moment to flush the whole system with the fluid grade printed on the reservoir cap and in the owner's manual.

How Hard Is the Job?

A front caliper swap on the S40 is a moderate DIY job for someone who has changed pads before: two guide pin bolts, one hose connection and a bleed. The rear is harder because of the parking brake. You need a caliper wind-back tool that matches the pattern on the piston face, and you need to reconnect and check the handbrake cable afterward. Use the torque values in the factory service manual for the bracket bolts, guide pins and hose fitting; do not guess.

Two rules that catch people out:

• Never press the brake pedal with a caliper or pads removed. The piston will push out of the bore.
• Bleed properly. The S40 has ABS, and a pedal that is still soft after a careful bleed may need the ABS unit cycled with a scan tool. Do not drive the car until the pedal is firm and high.

On recalls: NHTSA's recall list for the 2005 Volvo S40 shows campaigns for a T5 fuel line, the fuel pump electronic module and a portable GPS unit, but no brake caliper or brake hydraulic recall for this model year. A caliper problem on this car comes from wear and corrosion, not a factory defect campaign.

Frequently Asked Questions

Why will the rear caliper piston not push back on my 2005 S40?

Because the rear piston is part of the parking brake mechanism. It has to be rotated while it is pressed in, using a wind-back tool that engages the slots on the piston face. Make sure the handbrake is fully released first. If the piston will not turn or move with the correct tool, the caliper is likely seized and should be replaced.

Can I drive with a sticking caliper?

Not for long. A dragging caliper overheats the pad and rotor, cuts braking performance, and can cause a pull. If fluid is leaking or the brake warning is on, do not drive the car.

Should I replace both calipers or just the bad one?

If both calipers on the axle are original, replace them as a pair. They have aged the same way, and matching calipers keep braking even from side to side.

Do I need new pads and rotors with a new caliper?

New pads, yes, on both sides of the axle, because pads that ran on a dragging caliper are usually glazed or worn unevenly. Rotors only if they are under minimum thickness, scored, or heat damaged.

Will a new rear caliper fix a weak parking brake?

Often, if the old caliper's internal mechanism was seized. The cable must also move freely and be adjusted correctly, though. If the lever still has long travel with new calipers, check the cable and its adjuster.

Sources

1. Volvo S40 2005 Owner's Manual - parking brake lever location and rear-wheel application, brake failure and combined BRAKE/ABS warnings
2. Brake and Front End: Disc Brake Caliper Service - boot failure and piston corrosion, uneven inboard pad wear, replace vs rebuild, integrated parking brake calipers
3. Brake and Front End: Adjusting Parking Brakes - screw-type caliper piston position and cable tension
4. Motorist Assurance Program: 7 Common Signs of Brake Caliper Problems - caliper failure symptoms and causes
5. NHTSA: 2005 Volvo S40 recalls - recall campaigns listed for this model year