2009 Nissan GT-R Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2009 Nissan GT-R stops with Brembo monoblock calipers: six pistons up front and four at the rear, radially mounted and clamping 15-inch two-piece floating rotors. These calipers rarely fail outright. When owners do have caliper trouble it is almost always a sticking piston, a torn dust seal, a weeping piston seal or heat damage from hard driving, and most of it traces back to old fluid, heavy dust and skipped cleaning at pad changes.

How the 2009 GT-R brake system is built

Nissan's North American launch material for the 2009 GT-R lists Brembo monoblock six-piston front and four-piston rear calipers with 15-inch full-floating, cross-drilled, two-piece rotors and low-steel, high-stiffness pads, with the calipers radially mounted to reduce flex under hard braking. A monoblock caliper is machined from one piece of aluminum rather than two halves bolted together, which keeps it stiff, but it also means the caliper body is not something you split and reseal like a two-piece unit.

Rotor sizing matters when you shop for parts. Stock-size replacement rotors for the early (2008-2011, CBA chassis) GT-R are listed at 380 mm by 34 mm in front, with a 32 mm minimum thickness. The rear rotor is 380 mm by 30 mm. Later R35 cars moved to a different front rotor size, so always buy by model year, not just "R35."

The car is heavy for a sports car. MotoIQ's R35 project build puts it at about 3,800 pounds, and with 480 horsepower from the twin-turbo 3.8-liter V6 that is a lot of speed for four calipers to turn into heat.

Common caliper problems and their symptoms

Sticking or slow-returning pistons

This is the most common caliper complaint on any multi-piston monoblock. Brake dust and road grime pack in around the exposed piston faces, and when the pads wear and the pistons extend, that material gets pushed into the dust boots. One piston that drags will leave you with a car that pulls to one side under braking, a hot wheel after a drive, a burning smell, and a pad that wears into a taper because it is being pushed harder at one end than the other.

Torn dust boots and weeping piston seals

Once a dust boot tears, moisture and grit reach the piston bore. Corrosion there roughens the seal surface and the seal can start to weep. Look for wet fluid on the inside of the wheel, on the caliper body or on the pad backing plates, and for a brake fluid level that keeps dropping even though the pads still have life. A soft or sinking pedal together with a falling reservoir level is a stop-driving symptom.

Heat damage after track or canyon use

The stock system is strong on the street, but MotoIQ reports that on sticky tires the stock brakes give up after a few laps of track driving. Repeated overheating cooks dust boots and piston seals, boils old fluid and glazes pads. Symptoms: a long, soft pedal after hard use that firms up once things cool, a vibrating pedal, and blued or cracked rotor faces.

Dust, noise and rotor wear

MotoIQ also describes the factory pad as very aggressive, wearing rotors quickly and producing heavy dust. That dust is not only cosmetic: it is what fills the gaps around the pistons. If your wheels go dark within a few miles of washing, your calipers are collecting the same material.

What causes GT-R caliper trouble

• Old brake fluid. Glycol brake fluid absorbs moisture from the air. Power Stop notes fresh DOT 3 boils at 401 degrees F but drops to 284 degrees F fully degraded, while DOT 4 starts at 446 degrees F and up. Wet fluid both boils sooner and lets corrosion start inside the piston bores. Wagner points out that brake fluid also lubricates moving parts and prevents corrosion, which it can only do while it is in good condition.
• No cleaning at pad changes. Pushing pistons back without cleaning the exposed piston faces packs dust behind the boots.
• Sitting. Many GT-Rs are weekend cars. Long storage lets moisture and corrosion work on pistons that are not being cycled.
• Repeated overheating. Track days and long mountain descents on street pads and old fluid take the seals past their comfort zone.

Diagnosing a bad caliper on a 2009 GT-R

1. After a normal drive, compare wheel temperatures with an infrared thermometer. One corner clearly hotter than the others points to a dragging caliper.
2. With the wheel off, check pad thickness at both ends of each pad, and inner versus outer. Taper or a big inner/outer difference means pistons are not moving evenly.
3. Inspect every dust boot for tears and every piston area for wetness.
4. Check the fluid level and color at the reservoir. Wagner's guidance is simple: if the fluid is dark, have it tested, and if the level drops suddenly, have the system inspected.
5. Rule out the rotor. A pulsing pedal with even pad wear is usually a rotor thickness variation problem, not a caliper problem.

The fix: clean, reseal or replace

Clean and exercise. If the pistons are only sticky and the boots are intact, a thorough clean of the exposed piston faces during a pad change, followed by a full fluid flush, often solves it.

Reseal. On a monoblock you do not split the body. Seal kits replace the piston seals and dust boots from the outside, but the pistons must come out without damaging the bores, and six pistons per front caliper makes it slow, careful work. If a bore or piston is pitted, a seal kit will not fix it.

Replace the caliper. A caliper with pitted bores, a stripped bleeder, a cracked body or damaged mounting ears should be replaced. Replace calipers in axle pairs where condition is similar, so side-to-side braking stays even. Browse our brake calipers by vehicle, and use the factory torque values from the service manual for the caliper mounting bolts and bleeders.

What to replace at the same time

• Pads. A caliper that dragged has usually overheated or tapered its pads. Fit new brake pads on both sides of the axle.
• Rotors. Measure against the 32 mm front minimum and check for heat cracks around the drilled holes. For the 2009 car we carry the DBA 5000 Series XS drilled and slotted two-piece front rotor for the 2009+ GT-R, or see all brake rotors.
• Brake fluid. Any caliper service means a full flush with the factory-specified fluid, bleeding every bleeder on each multi-piston caliper.
• Hoses and lines. Check flexible hoses for swelling or cracking. Fresh brake lines are cheap insurance on a car that sees hard use.

How hard is the job?

Pad and rotor service on a GT-R is within reach of a careful home mechanic with proper lift points, a torque wrench and a way to bleed the system. Caliper resealing is harder: many pistons per caliper, tight bores, and no room for scoring a piston. Bleeding a car with multi-piston calipers takes patience to get every air pocket out. If the pedal is not firm and consistent after bleeding, do not drive the car until it is.

Frequently Asked Questions

Do 2009 GT-R Brembo calipers fail often?

Outright failure is uncommon. Most problems are sticking pistons, torn dust boots or leaking seals caused by old fluid, dust buildup and heat, and they are largely preventable with regular fluid changes and cleaning at pad changes.

Can I rebuild a monoblock caliper?

Yes, with seal and boot kits installed without splitting the body, as long as the pistons and bores are not pitted. If they are, replace the caliper.

Will later GT-R rotors fit my 2009?

Do not assume so. Stock-size rotors for the 2008-2011 car are listed at 380 x 34 mm front, and later R35s use a different front rotor. Always buy by model year.

What brake fluid should I use in my GT-R?

Use the fluid specified in your owner's manual and flush it on the factory schedule, or more often if you drive on track. Wet fluid lowers the boiling point and promotes corrosion inside the calipers.

Why does my GT-R pull to one side under braking?

A sticking caliper piston is the most likely brake cause, especially if that wheel runs hotter and its pads are worn unevenly. Tire pressure and alignment can also cause a pull, so check those too.

Why are my GT-R wheels always covered in brake dust?

The factory pad is an aggressive compound that produces heavy dust and wears rotors quickly. A lower-dust street pad can help, and keeping the calipers clean helps the pistons move freely.

Sources

1. Nissan News - All-New 2009 Nissan GT-R Comes to North America - Brembo monoblock 6/4-piston calipers, radial mount, 15-inch two-piece rotors, pads, VDC, engine output
2. Paragon - 2-Piece Front Rotors, Nissan GT-R R35 (CBA) - 380 x 34 mm front rotor, 32 mm minimum thickness, 2008-2011 fitment
3. MotoIQ - Project R35 GT-R brake upgrade - 380 x 30 mm rear rotor, vehicle weight, aggressive dusty factory pad, fade on track
4. Power Stop - Different Types of Brake Fluid - hygroscopic fluid, DOT 3 and DOT 4 boiling points, flush on OEM schedule
5. Wagner Brake - Facts About Vehicle Brake Fluid - fluid lubricates and prevents corrosion, checking level and color