2003-2009 Infiniti FX35 Brake Upgrade Options

By Core Brake Parts Tech Team — Circleville, OH warehouse

There are three real brake upgrades for a 2003-2009 Infiniti FX35, and they stack in this order: a better front pad compound first, slotted or premium replacement rotors second, and fresh fluid plus hardware every time you are in there. The FX is a heavy, fast SUV on factory-sized discs, so heat management is the whole game. None of it requires cutting or a caliper bracket adapter if you stay with direct-fit parts for your exact model year.

What the factory FX35 brake system actually is

Infiniti's own specification sheets tell you what you are working with. The FX35 runs four-wheel ventilated discs with four-channel ABS, Brake Assist and Electronic Brake force Distribution - no rear drums, no multi-piston calipers. The front disc is the bigger, harder-working end, and the rear is a much thinner disc.

That last row matters. The FX50 got aluminum opposed-piston calipers and much larger discs; the FX35 did not. If you have read that the FX has big brakes, that is the V8 car. Your upgrade path works within the 12.6-inch front and 12.1-inch rear envelope, which is plenty capable once the friction and the fluid are right.

Why FX35 brakes start feeling soft or noisy

Three things gang up on this platform. Mass: even the lightest FX35 is over two tons before passengers, and an AWD 2009 car is close to 4,300 lbs. Power: it is quick, and speed you gain easily is heat you have to shed. And wheel choice - the FX35 came on 18 x 8.0-inch alloys with 20-inch wheels available, and larger wheels with heavier tires raise rotating mass that the same-size discs still have to stop.

Symptoms that point at friction and heat rather than a hydraulic fault:

• Fade on a long grade or after a few hard stops - the pedal stays firm but the vehicle slows less. The pad compound is past its usable temperature.
• Pedal pulse or steering shimmy under braking - usually uneven pad material on the disc face, not a literally bent rotor.
• Heavy dust and a low-speed groan - a soft pad doing its job badly on a heavy SUV.
• A spongy pedal that firms on the second push - a fluid and air problem, and no pad upgrade fixes it.

Upgrade one: the front pad compound

Pads are the cheapest change with the largest effect, and on an FX the fronts do most of the work. A truck-and-SUV compound is formulated for the higher loads and longer stops a 4,300 lb vehicle produces, while a street-and-track compound trades some cold bite and low dust for higher temperature capability. For a 2006-2009 FX35, the EBC Greenstuff 6000 Series front pad set, DP61671, is the SUV-specific option. If your car is a 2003-2005 and you want more heat range at the rear axle, the EBC Yellowstuff rear pad set, DP41666R, is the street-and-track compound for that application. Browse the full range of brake pads if you want to compare compounds side by side.

One rule: do not pair an aggressive front pad with a tired rear pad. Brake balance on the FX is managed electronically, but the system can only distribute what the friction at each corner can actually deliver.

Upgrade two: slotted rotors, and what slots really do

Slotted and cross-drilled discs are the most misunderstood part of a brake upgrade. Power Stop's technical write-up is blunt about the division of labor: slots remove the gas and dust trapped between the pad and the rotor face, while drill holes work on airflow and convective cooling through the vanes. Slots do not meaningfully increase heat transfer, and drill holes do not scrub the pad face. Neither makes a disc stop harder on its own - they keep the friction surface consistent when it is hot.

For a heavy SUV that sees repeated hard stops rather than track sessions, slotting is the safer choice because it adds no holes to a casting that has to survive hard thermal cycling. For 2003-2005 FX35 rear applications we carry two slotted options: the EBC GD Sport rear slotted rotors, GD7219, and the EBC USR slotted rear rotors, USR7219. The wider catalog of brake rotors covers plain replacement discs as well, which remain a perfectly good answer if your complaint is worn parts rather than fade.

When a plain premium rotor is the better buy

If the car pulses, dusts heavily or squeals but has never faded on you, you have a surface-condition problem, not a heat problem. A quality plain disc with a good pad fixes it for less than a slotted set costs, and it runs quieter.

Getting fitment right on a 2003-2009 FX35

This model year span covers two different vehicles. The 2003-2008 FX and the redesigned 2009 FX share the same listed disc dimensions on the FX35, but the surrounding hardware is not interchangeable across the redesign, and aftermarket applications inside the first generation split at the 2006 model year - which is why the rear rotors above are listed for 2003-2005 specifically. Before ordering:

1. Confirm your model year and whether the vehicle is rear-wheel drive or all-wheel drive.
2. Confirm the trim - if it is an FX45 or FX50, the part numbers here do not apply.
3. Match the part to your exact year range rather than to the generation.
4. Measure the existing disc if the brake history is unknown and non-original parts may already be on the car.

What to replace at the same time

Fluid is the upgrade most people skip. Infiniti's own maintenance information explains why it is a wear item: brake fluid transfers pedal force to the brakes, and as it ages it absorbs moisture that can flash into a compressible gas, reduce braking efficiency and promote corrosion. Federal standard FMVSS 116 sets the minimums - DOT 3 must hold at least 401 degrees F dry and 284 degrees F once it has absorbed moisture, DOT 4 at least 446 degrees F dry and 311 degrees F wet. Use the DOT specification printed on your master cylinder cap and in your owner's manual, and flush the system rather than topping it off.

Also worth doing while the caliper is off: replace the hardware and clips so the pads slide freely, clean and lubricate the caliper guide pins, and inspect the parking brake shoes inside the rear rotor hat, since those only get looked at when the rear disc comes off. A seized slide pin will ruin a new pad set in a few thousand miles. See our brake hardware kits and, if a caliper is sticking rather than just dirty, our brake calipers.

How hard is the job, and the bed-in you cannot skip

Pads and rotors on an FX35 are a straightforward two-to-three hour job for someone comfortable with a torque wrench and jack stands, and the rear takes longer than the front because of the parking brake mechanism inside the rotor hat. Torque every fastener to the value in the factory service manual - caliper bracket bolts in particular are a safety item, not a guess.

Then bed the brakes in before you drive normally. Power Stop's published procedure is five moderate-to-aggressive stops from 40 mph down to 10 mph in quick succession without coming to a full stop, then five more from 35 mph to 5 mph, then roughly five minutes of moderate driving with no hard stops so the brakes cool. The point is to lay down an even layer of pad material on the disc. Skip it and you get the uneven deposits that produce pedal pulsing and steering vibration - the exact symptom most owners blame on a warped rotor.

Frequently Asked Questions

Will FX50 brakes bolt onto my FX35?

Not as a simple swap. The FX50 uses aluminum four-piston opposed front calipers on a 14.0-inch disc and two-piston opposed rears on a 13.8-inch disc, against the FX35's 12.6-inch front and 12.1-inch rear. Different calipers, different mounting and different disc dimensions make that a full big-brake conversion, not a parts-bin upgrade.

Are there any brake recalls on the FX35?

A NHTSA recall lookup for the 2006 FX35 returns campaigns covering front air bags and inflators, rear combination lamps, headlamps and a fuel filler hose - none for the brake system. Always run your own VIN through the NHTSA recall tool, because campaigns are added over time and vary by model year.

Should I go slotted or cross-drilled on a heavy SUV?

Slotted, in most cases. Slots vent gas and dust from between the pad and rotor face without removing material from a casting that has to absorb a lot of heat on a two-ton vehicle. Cross-drilling helps convective airflow, but a solid slotted disc is the more conservative choice for street and towing use.

How much can a 2003-2009 FX tow, and does that change my brake choice?

Infiniti rated the 2008 FX at up to 3,500 lbs maximum, while for 2009 the FX35 rear-wheel drive is not rated for towing, the FX35 AWD is rated at 2,000 lbs and the FX50 at 3,500 lbs. If you tow anywhere near those numbers, prioritize a higher-temperature pad compound and fresh fluid over cosmetic rotor features.

Do I have to replace rotors every time I do pads?

No, but measure. If the disc is above the minimum thickness stamped on it, has an even friction surface and no hard scoring or heat checking, a fresh pad set on a properly cleaned disc is fine. If it is at or near minimum, replace it - a thin disc holds less heat and fades sooner, which is the opposite of what an FX needs.

Sources

1. 2008 Infiniti FX Specifications (Infiniti USA) - FX35 front 12.6 x 1.3-inch and rear 12.1 x 0.6-inch ventilated discs, curb weights, wheel sizes and the 3,500 lb maximum tow rating.
2. 2009 Infiniti FX Specifications (Infiniti USA) - 2009 FX35 disc sizes and four-channel ABS, FX50 opposed-piston calipers with 14.0-inch front and 13.8-inch rear discs, curb weights and tow ratings.
3. Power Stop: Drilled vs Slotted Rotors - what slots do for gas and dust removal versus what drill holes do for convective cooling.
4. Power Stop: Brake Pad Break-In Procedure - the stop-by-stop bed-in sequence and the pedal pulsation that uneven pad deposits cause.
5. Infiniti Maintenance Schedules: 2009 FX35 Brake Fluid - brake fluid absorbs moisture that can become a compressible gas and reduce braking efficiency.
6. FMVSS 116, 49 CFR 571.116 - minimum dry and wet equilibrium reflux boiling points for DOT 3 and DOT 4 brake fluid.
7. NHTSA Recalls by Vehicle: 2006 Infiniti FX35 - the campaigns on record for this vehicle, none of which cover the brake system.