2003-2009 Infiniti FX35 Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake caliper trouble on a 2003-2009 Infiniti FX35 comes down to three things: guide pins that rust and stop sliding, a piston that sticks in its bore, or a caliper that is leaking brake fluid. The warning signs are a pull to one side, one wheel that runs much hotter than the others, a burning smell, and pads that wear unevenly. Early 2003 models also had a safety recall on the front caliper mounting bolts, so check that first.

The 2003 FX35 Front Caliper Bolt Recall

NHTSA campaign 03V476000 covers certain 2003 Infiniti FX35s. The recall says the front brake caliper mounting bolts may not have been tightened enough at the factory, so one or both bolts could loosen. If that happens, the caliper can rotate or come off its mounting bracket. NHTSA lists the possible results as brake failure, wheel damage, a flat tire, or a crash. The fix was for dealers to tighten the front caliper mounting bolts. Infiniti began notifying owners on January 5, 2004.

If you own a 2003, put your VIN into the NHTSA recall lookup or ask any Infiniti dealer whether the work was done. On an FX35 this old it has almost certainly been done already. Still, any shop pulling a front caliper should torque the mounting bolts to the factory service manual value when it goes back on. A caliper bolt that is left loose, or tightened with an impact gun and never checked, is the same problem the recall was issued to fix.

NHTSA's recall list for the 2004 and 2006 FX35 shows no brake recalls. The open campaigns on those years are for airbag inflators, lighting and the fuel filler hose. For a 2004-2009 FX35, caliper trouble is normal wear and age, not a factory defect.

How the FX35 Caliper Works and What Fails

When you press the pedal, fluid pressure pushes the caliper piston out and squeezes the pads against the rotor. When you let off, a square-cut rubber seal around the piston pulls it back a little so the pads stop touching the rotor. On a sliding (floating) caliper, the caliper body moves on two greased guide pins so the inner and outer pads press evenly. On a fixed multi-piston caliper, the body stays put and there are pistons on both sides of the rotor.

Here is how each part tends to fail on a high-mileage FX35:

• Guide pins seize. ADVICS, an OE brake supplier, names three causes: the slide pin sticks, the pin rusts once its grease is gone, and heat and friction damage the pin boot and sleeve. When a pin seizes, the caliper cannot float. One pad drags and wears much faster than the other.
• Piston sticks. Once the dust boot splits, water and grit get past it and rust the piston. The piston goes out when you brake but will not come back, so the pad stays against the rotor.
• Seals wear out. EBC notes that most vehicles use EPDM rubber for caliper seals and that EPDM seals are not designed for use above 140-150 degrees C. A caliper that drags keeps heating itself, and the heat damages the seal, so the caliper drags even more.
• The caliper leaks. Wet streaks on the inside of the wheel, a falling fluid level in the reservoir, or a pedal that sinks slowly all point to a piston seal or bleeder that is leaking.

Symptoms and How to Diagnose Them

EBC puts it simply: sliders and pins in calipers corrode and make the pads drag, and pad drag leads to overheated brakes and squeal. Their technical team also warns that a sticking caliper often gets blamed on the pad compound. If you have gone through two sets of pads quickly on one corner, look at the caliper, not the pad brand.

Rebuild, Service or Replace?

Not every caliper problem needs a new caliper. Use this order:

1. Pins only. If the piston moves freely and nothing leaks, pull the guide pins, clean them, and look for pitting. Replace any pin that is rusted and any boot that is torn, then use the right grease. ADVICS recommends anti-rust lubricant on the pin itself and a rubber-safe grease on the boot and sleeve. Petroleum grease on rubber boots makes them swell and stick.
2. Replace the caliper. If the piston is pitted, will not push back smoothly, or the caliper is leaking, replace it. A rebuild kit only works when the bore is clean. On an older SUV from the rust belt it rarely is, and a remanufactured or new caliper with a bracket saves time and a second trip under the car.
3. Replace in pairs. Replace calipers on both sides of the same axle so they apply at the same rate. If you replace only one, the car can still pull.

Shop replacement brake calipers and match the part to your model year and axle. FX35 parts are not the same from start to finish, so always check the listing fitment. For example, the front pads we carry for this SUV are listed for 2006-2009 and the rear parts for 2003-2005.

What to Replace at the Same Time

A caliper that has been dragging cooks the pads and rotor on that corner too. When you do a caliper job on an FX35, plan on:

• Pads. Pads that ran hot are often glazed or tapered. For 2006-2009 fronts, the EBC Greenstuff 6000 front pad set for the 2006-2009 FX35 is built for SUV weight. For 2003-2005 rears, the EBC Yellowstuff rear pad set is a street and track compound for owners who drive hard.
• Rotors. If the rotor is blue, grooved or pulsing, replace it. Rear options for 2003-2005 include the EBC GD Sport slotted rear rotors and the EBC USR slotted rear rotors.
• Hardware. New abutment clips and pin boots from our brake hardware kits are cheap insurance against the same pins seizing again.
• Hoses. A rubber brake hose can collapse inside and hold pressure on the caliper, which acts just like a sticking piston. If a new caliper still drags, check the hose. See our brake hoses.
• Fluid. Opening the system is a good time to flush old fluid. EBC recommends changing brake fluid every two years for normal road use. Use the fluid type printed on your master cylinder reservoir cap or in the owner's manual.

How Hard Is the Job?

Swapping a loaded caliper on an FX35 is a moderate DIY job with hand tools. You need a jack, jack stands, and a torque wrench. Unbolt the brake hose banjo bolt (fit new copper crush washers), remove the caliper and bracket bolts, fit the new caliper, and torque every bolt to the factory service manual value. That last step is exactly what the 2003 recall was about.

The part many owners skip is bleeding. Any time you open the hose, you have to bleed that caliper until the fluid runs clear with no air. The FX35 has ABS and stability control, so if the pedal is still soft after a normal bleed, a shop with a scan tool can cycle the ABS unit while bleeding. After the job, bed in the new pads with a series of moderate stops before any hard braking. Then drive it and check that no wheel runs hotter than the others.

Frequently Asked Questions

Was there a brake caliper recall on the Infiniti FX35?

Yes, for certain 2003 models. NHTSA campaign 03V476000 covers front caliper mounting bolts that may not have been tightened enough. Dealers tightened the bolts. NHTSA lists no brake recalls for the 2004 or 2006 FX35.

Can I drive with a sticking caliper?

Only a short distance to get it fixed. A dragging caliper overheats the pad, rotor, seals and fluid, and it can make the SUV pull under hard braking. If you see a fluid leak, do not drive it.

Should I replace both calipers or just the bad one?

Replace them in pairs on the same axle. A new caliper on one side and an old one on the other can apply unevenly and make the vehicle pull.

Why does my inner brake pad wear faster than the outer one?

On a sliding caliper, the inner pad is pushed directly by the piston. If the guide pins seize, the caliper cannot slide to pull the outer pad in, so the inner pad does most of the work. Clean or replace the pins and boots.

Do I need to replace rotors when I replace a caliper?

Not always. If the old caliper was dragging long enough to blue, groove or warp the rotor, replace it. Otherwise measure it against the minimum thickness stamped on the rotor.

What brake fluid does an FX35 use?

Use the specification printed on the master cylinder reservoir cap or in your owner's manual. Do not mix in silicone fluid. EBC recommends a fluid change every two years for road use.

Sources

1. NHTSA recall data, 2003 Infiniti FX35 - campaign 03V476000 front caliper mounting bolts, consequence, remedy, notification date
2. NHTSA recall data, 2006 Infiniti FX35 - no brake recalls listed for this model year
3. ADVICS - Troubleshooting Caliper Slide Pin Sticking - causes of sticking pins and the correct greases
4. EBC Brakes - Technical Braking Q&A - EPDM seal temperature limit, fluid change interval
5. EBC Brakes - Brake Pad Tapered Wear - taper causes including seized pistons, normal taper