2013-2018 Cadillac ATS Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2013-2018 Cadillac ATS the front pads almost always wear out first, because the front axle does most of the stopping on every car. The rear axle is not maintenance-free, though: the rear rotors carry the parking brake inside them, the rear caliper bracket bolts are one-time-use, and rear pads that get skipped at a front brake job tend to surprise owners a few thousand miles later. Here is how the ATS brake system is built, what to check at each end, and what to replace together.

How the ATS brake system is laid out

Brake & Front End magazine, the trade publication for undercar technicians, describes two brake packages for the ATS. The base package, GM option code JE5, uses a single-piston sliding caliper at all four corners. The performance package, option code J55 or J6, uses larger rotors and a four-piston fixed caliper up front. The performance package is the one most people call "the Brembo brakes." Both packages use disc brakes front and rear.

Which package you have matters more than the model year when you order parts. Pads, rotors and calipers from the base system do not interchange with the performance system. The option codes are printed on the Service Parts Identification label, usually in the glove box or trunk, and a dealer can read them from the VIN. The front and rear kit we carry for this car is built for the base brakes, so check for JE5 before you order.

Front vs rear: what wears first and why

When you brake, weight shifts forward and loads the front tires, so the front pads and rotors do the larger share of the work and wear faster. On the ATS that means the front pads are normally the first brake item you replace. The rears still wear, and because stability and traction control systems apply individual brakes, rear pad wear on a newer car can be closer to the fronts than older rules of thumb suggest. The only way to know is to measure both ends.

GM's owner manual for the ATS gives the practical schedule: inspect the brake pads when the tires are rotated, and replace brake pads as complete sets. A complete set means both sides of the same axle, never one wheel. Replacing only the front pads is fine when the rears still have good lining left, but look at them while the wheels are off rather than assuming.

Rotors on the ATS last longer than you might expect

GM built the ATS with Ferritic Nitro-Carburized (FNC) rotors. FNC is an extra manufacturing step that forms a hardened surface layer, which resists rust and lets the rotor wear more slowly. According to Brake & Front End, it also reduces the thickness variation that causes pulsation when a car sits and the rotor faces rust unevenly. The result is that ATS rotors often outlast one set of pads. When you do replace rotors, replace the pads with them so the new friction surfaces bed in together.

Symptoms and how to diagnose them

• High-pitched squeal while driving that stops when you press the pedal firmly. The owner manual says the ATS disc brake pads have built-in wear indicators that make this sound when the pads are worn. Pull the wheels and measure; it can be either axle.
• Grinding. The lining is gone and the backing plate is cutting the rotor. Replace pads and rotors on that axle.
• Pulsation or steering-wheel shake under braking. On FNC rotors, GM's guidance reported by Brake & Front End is to try a burnish first rather than machining the rotors. Unevenly torqued wheel nuts also cause pulsation; the owner manual calls for tightening them evenly, in the proper sequence, to specification.
• Squeal on light first stops, especially with the performance package. This can be normal. GM's fix for performance-package noise is a moly lubricant on the pad ears and edges, not on the back of the pad.
• Brake fluid level dropping. The manual lists only two causes: normal lining wear or a leak. Do not top it off to cover worn pads; add or remove fluid only when the hydraulic system is serviced.
• SERVICE PARKING BRAKE message. A fault in the parking brake system; have it diagnosed before assuming it is a pad problem.

Doing the job: front and rear differences

Caliper bracket bolts are torque-to-yield

This is the detail that trips up DIY brake jobs on the ATS. Brake & Front End reports that the caliper bracket bolts at both ends are torque-to-yield: they are tightened to a torque value and then turned an additional angle, and they should not be reused. They must be installed clean and dry, with no oil, grease or sealer on the threads, and never run in with an impact wrench. The front and rear bolts have different torque and angle specifications, so follow the factory service information for your car and buy new bolts before you start.

The rear rotors hold the parking brake

The ATS parking brake uses small drum shoes inside the "hat" of the rear rotor, applied either by a manual cable or by an electronic parking brake (EPB) switch in the console. To pull a rear rotor on an EPB car, the parking brake cable tension has to be released first, with a scan tool or with the switch-and-pedal release procedure in the service information. In some cases the parking brake shoes also need adjustment to fit the rotor. After the job, apply and release the parking brake a few times and confirm there is no warning message before you drive.

When to machine and when to replace

GM's guidance, as summarized by Brake & Front End, is to machine these rotors only when they are deeply scored, have excessive lateral runout, or have measurable thickness variation, and then only with an on-car lathe. Otherwise, a rotor that is still above minimum thickness and runs true can go back on with new pads. Because the FNC layer is part of what makes these rotors rust-resistant, many owners simply replace rotors at the second pad change rather than machining them.

What to replace at the same time

• Pads in axle sets. If a front job is due and the rears are close, doing all four at once saves a second teardown. A front and rear brake kit for the 2013-2018 Cadillac ATS with base brakes covers both axles in one order.
• Rotors when they are scored, below minimum thickness, or causing pulsation that a burnish does not cure. Browse replacement brake rotors and ceramic brake pads. Brake & Front End notes the factory base pads are a ceramic or non-asbestos organic formulation, and that aggressive semi-metallic pads can shorten rotor life.
• Hardware and bolts. New abutment clips and slide pin boots from a brake hardware kit, plus new torque-to-yield bracket bolts.
• Brake fluid if it is due. The 2017 ATS maintenance schedule calls for replacing the brake fluid every five years, using GM approved DOT 3 from a clean, sealed container. Doing it with the pads is efficient because the wheels are already off.

Burnishing new pads and rotors

New pads need to lay an even transfer layer onto the rotor. The procedure GM recommends for the ATS, as reported by Brake & Front End, is 10 to 15 moderate stops from 35 mph with cooling time between each stop. Avoid hard stops in the first miles. If you plan to take a car with the Brembo package on track, the owner manual states that performance or racing pads are required before closed-track driving on base vehicles, and that racing brake fluid must be replaced with GM approved fluid before driving on public roads.

Recall note: NHTSA campaign 15V358000 covered certain 2015 ATS and CTS cars with a bracket between the brake pedal and the actuating rod that could fracture. It is not a pad or rotor issue, but if you own a 2015 ATS, check your VIN on nhtsa.gov to confirm the remedy was done.

Frequently Asked Questions

Do the front brakes on a Cadillac ATS wear faster than the rear?

Usually, yes. The front axle does most of the braking, so front pads are typically replaced first. Rear pads still wear and should be checked at every tire rotation, as the owner manual recommends.

Can I replace just the front pads on my ATS?

Yes, as long as both front wheels are done together and the rear pads still have good lining. GM calls for replacing pads as complete sets, not one wheel at a time.

How do I know if my ATS has base brakes or Brembo brakes?

Look for option code JE5 (base) or J55/J6 (performance) on the Service Parts Identification label, or ask a dealer to decode the VIN. The performance package has a four-piston fixed front caliper you can see through the wheel.

Do I need a scan tool to change the rear brakes on an ATS with an electronic parking brake?

A scan tool makes it easiest, but the service information also gives a switch-and-pedal procedure to release the parking brake cable tension without one. Release it before removing the rear rotors.

Can I reuse the caliper bracket bolts?

No. The ATS caliper bracket bolts are torque-to-yield and should not be reused. Install new bolts dry and tighten them to the torque-plus-angle value in the factory service information.

What brake fluid does the Cadillac ATS use?

GM approved DOT 3 brake fluid, per the owner manual. Do not use silicone-based fluid.

Sources

1. Brake & Front End - Brake Job: 2012-Current Cadillac ATS - JE5 and J55/J6 brake packages, caliper types, FNC rotors, torque-to-yield bracket bolts, burnish procedure, machining criteria, drum-in-hat parking brake and EPB release
2. Cadillac ATS/ATS-V 2017 Owner Manual (GM) - built-in pad wear indicators, replace pads as complete sets, inspect pads at tire rotation, DOT 3 fluid, five-year fluid replacement, track pad and fluid requirements
3. NHTSA recalls database - 2015 Cadillac ATS - recall 15V358000, brake pedal bracket