2006-2007 Subaru Tribeca Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2006-2007 Subaru B9 Tribeca the front brakes almost always wear out first, because the front axle does the majority of the stopping work. The rear brakes last longer but are not maintenance-free: the rear rotor also houses the drum-style parking brake, and rear pads can wear faster than expected if a caliper sticks. Here is how to tell which end needs work and what to replace together.

How the Tribeca B9 brake system is laid out

The B9 Tribeca uses disc brakes at all four corners with ABS and Electronic Brake Force Distribution (EBD). EBD is the part of the ABS system that adjusts how much pressure goes to the rear wheels. With the family aboard and the cargo area full, the rear brakes can contribute more; with the SUV empty, rear pressure is held back so the rear wheels do not lock.

The rear rotor is a larger part than many owners expect. Centric's catalog listing for its rear rotor that fits the 2006-2007 B9 Tribeca and the 2008-2014 Tribeca gives these figures:

That drum-in-hat design matters. The parking brake on this SUV is a small set of shoes that expand against the inside of the rear rotor hat, separate from the rear pads. When you replace rear rotors you are also replacing the parking brake drum surface, so check the parking brake shoes at the same time.

For the front, always measure your rotor against the minimum thickness stamped on the rotor itself rather than relying on a number from memory. The front and rear rotors are different parts and are not interchangeable.

Why the front brakes wear first

When you brake, the Tribeca's weight pitches forward onto the front tires. The front tires gain grip and the rear tires lose some, so the system is designed to send most of the braking effort to the front. The Motorist Assurance Program puts the front share of braking force at roughly 70 percent on a typical vehicle. More work means more heat and more pad material worn away, so front pads and rotors come due before the rears on most Tribecas.

The Tribeca adds a few factors of its own:

• Weight. It is a three-row, all-wheel-drive SUV with a six-cylinder engine up front, so the front brakes carry a heavy load on every stop.
• Towing and full loads. A loaded third row or a trailer puts more heat into every stop at both ends.
• Stop-and-go driving. Short trips and city traffic wear pads far faster than highway miles.

The realistic pattern is that the fronts need pads more often than the rears. Do not assume the rears are fine just because the fronts were just done. Inspect all four corners every time the wheels come off.

Symptoms and how to tell which end needs work

Front brake symptoms

• Squealing from a wear indicator tab when you brake lightly.
• Steering wheel shake or a pulsing pedal during braking, which usually points to front rotor thickness variation.
• The SUV pulls to one side under braking, often a sticking front caliper or collapsed hose.
• Grinding, which means the pad is down to the backing plate and the rotor is being damaged.

Rear brake symptoms

• A pulsing felt more in the seat and body than in the steering wheel.
• A parking brake that needs more travel than it used to, or does not hold on a hill.
• One rear wheel noticeably hotter than the other after a drive, a sign of a dragging caliper or parking brake.
• Uneven rear pad wear, with the inner pad much thinner than the outer, which points to seized caliper slides.

What the warning lights tell you

The Tribeca owner's manual explains that the red brake system warning light comes on when the brake fluid level drops to near the MIN mark on the reservoir. If it lights while driving with the parking brake released, the manual says it could mean leaking fluid or worn brake pads, since the fluid level falls as pads wear and the caliper pistons extend. The same light also comes on, usually together with the ABS light, if the EBD system has a fault. The manual notes the conventional brakes still work if EBD fails, but the rear wheels become more likely to lock. Either way, have the SUV inspected before driving it further.

The fix: which parts to replace

Pads are always replaced as an axle set, both sides at once, so braking stays even from left to right. Rotors should be measured with a micrometer; if either rotor on an axle is at or under the discard thickness, or has thickness variation that causes pulsation, replace both rotors on that axle.

• Front pads: start with our brake pads for your vehicle. For a Tribeca that tows or is driven hard, a performance street compound such as the Hawk HPS 5.0 front pads for the 2006-2007 B9 Tribeca is a good match. For daily driving with low dust, look at ceramic brake pads.
• Rotors: shop replacement brake rotors and confirm front or rear position, since the two are different parts.
• Hardware: new abutment clips and slide pin boots from our brake hardware kits prevent the rattles and uneven wear that old, rusted clips cause.
• Calipers: if a caliper piston is seized or a slide pin will not move freely after cleaning, replace it with one of our brake calipers.

What to replace or service at the same time

• Caliper hardware and lube. Wagner's brake job procedure calls for installing new caliper hardware with the pads and applying brake lubricant under and on top of the clips to keep rust from binding the pads.
• Hub face. Clean the hub where the rotor seats. Wagner warns that rust on the hub can cause runout, which the driver feels as brake pulsation.
• Parking brake shoes (rear). Because the parking brake drum is inside the rear rotor hat, inspect the shoes and adjust them when rear rotors are replaced.
• Brake fluid. Check the level and condition. The owner's manual warns never to mix different brands of brake fluid, and to avoid mixing DOT 3 and DOT 4 even within the same brand. Use the fluid type printed on your reservoir cap and in the manual's fluids section.
• Hoses. Look for cracks or bulging on the rubber lines; our brake hoses are an inexpensive fix while the wheel is off.

How hard is the job?

Front pads and rotors on the B9 Tribeca are a moderate DIY job with basic hand tools, a torque wrench, and a jack with proper stands. The rear is a step harder because the parking brake shoes sit inside the rotor hat: the parking brake must be fully released, and sometimes backed off at the adjuster, before a worn rotor will slide off. Tighten the caliper bracket bolts and lug nuts to the values in the factory service manual with a torque wrench.

Once the new parts are in, bed the pads. Wagner recommends a 30-30-30 routine: 30 stops from about 30 mph, with 30 seconds of cooling between each. This lays down an even layer of pad material on the rotor for smooth, quiet stops.

Frequently Asked Questions

Should I replace front and rear brakes on my Tribeca at the same time?

Only if both ends are worn. The front pads usually wear out first, so it is common to do the fronts on their own. Measure the rear pads and rotors every time and replace them when they reach their limits.

Why are my rear pads wearing faster than the fronts?

That is not normal on a Tribeca. The usual causes are seized caliper slide pins, a sticking caliper piston, or a parking brake that is not releasing fully. Check each rear wheel for heat after a drive and inspect the slides.

What is the minimum thickness for a 2006-2007 B9 Tribeca rear rotor?

Centric lists a nominal thickness of 18.0 mm and a discard thickness of 16.0 mm for its rear rotor that fits the 2006-2014 Tribeca. The discard figure is also stamped on the rotor itself; go by that stamp.

Do 2008-2014 Tribeca rear rotors fit my 2006-2007 B9 Tribeca?

Centric's rear rotor listing covers both the 2006-2007 B9 Tribeca and the 2008-2014 Tribeca with the same part. Always confirm fitment by year and position before ordering.

What does the red brake light mean on a B9 Tribeca?

With the parking brake off, it means low brake fluid, which can be a leak or worn pads, or an EBD fault if it lights with the ABS light. Have the brakes inspected before continuing to drive.

Sources

1. Centric 120.47028 rear rotor listing - rear rotor diameter, 18 mm nominal and 16 mm discard thickness, vented, drum-in-hat, 2006-2014 Tribeca fitment
2. Subaru Tribeca Owner's Manual - Brake system warning light - fluid level warning, worn pads, EBD fault behavior
3. Subaru Tribeca Owner's Manual - Recommended brake fluid - do not mix brands or DOT 3 with DOT 4
4. Motorist Assurance Program - Which brakes go bad first - front brakes handle about 70 percent of braking force
5. Wagner Brake - Replacing brake pads and rotors - new hardware and lube, hub rust causes runout, 30-30-30 bedding