2017-2019 Buick Lacrosse Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2017-2019 Buick LaCrosse the front brakes almost always wear out first, because the front axle does most of the stopping on a front-heavy sedan. The rear brakes last longer but are more involved to service, since each rear caliper carries the electric parking brake motor. Plan on front pads more often, check the rears at every front job, and replace rotors in axle pairs when they are worn or out of spec.

How the LaCrosse brake system is laid out

Buick's launch material for the redesigned 2017 LaCrosse describes a split, dual-circuit, four-wheel-disc system with power assist, Duralife brake rotors, brake pre-fill and Electronic Brake Force Distribution. The same release lists an electronic parking brake and Hill Start Assist with Automatic Vehicle Hold. In practice that means:

• Front: disc rotors with single-caliper pads. These carry most of the braking load on every stop.
• Rear: disc rotors and pads, with the parking brake built into the rear calipers and applied by an electric motor rather than a cable and drum.
• Hydraulics: the owner's manual calls for DOT 3 brake fluid from a sealed container.

For 2018, Buick made a 2.5L four-cylinder with eAssist light electrification standard, with the 3.6L V6 available on select trims. Buick's release states that when braking or coasting, some of the energy normally lost is converted to electricity and stored in a small lithium-ion pack. That regenerative effect takes a share of the light, everyday deceleration off the friction brakes, so an eAssist car can see somewhat longer pad life in stop-and-go driving than an otherwise similar V6 car. It does not change which axle wears first.

Why the front brakes wear first

When any car brakes, weight shifts forward onto the front tires. The front tires then have the most grip, so the system is designed to send the larger share of braking force to the front. Electronic Brake Force Distribution uses the ABS hardware to fine-tune that front-to-rear balance as load changes, which protects the rear from locking up but also means the rear pads do comparatively light work.

The result is predictable: front pads are the wear item you replace most often on a LaCrosse, and front rotors take more heat than the rears. Hard city driving, hilly terrain and frequent heavy stops all speed this up. Highway commuters will see much longer intervals on both axles.

Duralife rotors: why LaCrosse rotors often outlast the first set of pads

Duralife is GM's name for rotors treated with ferritic nitro-carburizing (FNC). Trade coverage of the process describes rotors held in a nitrogen-rich 560 degree C oven for 24 hours, leaving a very thin corrosion-resistant layer on the iron. GM's goal was to stop the uneven rust buildup that causes thickness variation, which drivers feel as pedal pulsation and steering shudder, and the same coverage cites GM doubling average rotor life expectancy from 40,000 to 80,000 miles. The LaCrosse was one of the first models named as using these rotors, and Buick's 2017 release says they offer up to double the service life of conventional rotors.

What that means at brake time: on a LaCrosse it is common for the first front pad replacement to happen while the factory rotors are still usable. Measure them. If the rotors are above the minimum thickness cast into the rotor and show no pulsation, deep scoring or heat spots, new pads alone can be the right call. Once rotors are thin, grooved, or causing a shake, replace them as a pair on that axle. Keep in mind that the treated layer is extremely thin, so a machined rotor loses that corrosion protection on its braking surface.

Symptoms and how to tell which end needs work

• High-pitched squeal while driving that changes or stops when you brake: often a pad wear indicator touching the rotor. Check the front first.
• Grinding or metal-on-metal noise: pads are worn to the backing plate. Stop driving on it; rotor damage is next.
• Pulsation in the pedal or a steering-wheel shake under braking: usually front rotor thickness variation. A shake felt in the seat rather than the wheel points more toward the rear.
• Brake warning light or low fluid: the owner's manual warns that low fluid can mean worn linings or a leak, and says not to simply top it off. Worn pads let the caliper pistons extend, which lowers the reservoir level.
• Parking brake warning light or message: the amber EPB warning points to the electric parking brake system, not normal pad wear. Diagnose it before starting rear brake work.

The honest way to know is to pull the wheels and look. Compare inner and outer pad thickness on both axles; uneven wear between the two pads on one caliper suggests sticking slide pins or a dragging piston rather than normal wear.

Replacing the front brakes

The front job is a conventional pad and rotor service and is the one most LaCrosse owners will do first. Our 2017-2019 Buick LaCrosse front ceramic brake pads are listed for this generation. If you want matched parts, browse replacement brake rotors and ceramic brake pads, and confirm fitment by year, drivetrain and trim before ordering.

Replace at the same time:

• Abutment clips and pad hardware, from a brake hardware kit if the new pads do not include them.
• Caliper slide pin lubrication, using a brake-specific lubricant, and new boots if the old ones are torn.
• Rotors, as a pair, if they are below minimum thickness or cause pulsation.

Torque the caliper bracket bolts, caliper bolts and wheel nuts to the values in the factory service information, and bed in the new pads with a series of moderate stops before any hard braking.

Replacing the rear brakes: the electric parking brake step

The rear pads and rotors themselves are no harder to swap than the fronts. The difference is the electric parking brake. Each rear caliper has a motor that drives the piston to clamp the pads when the parking brake is applied, so the piston cannot simply be pushed back with a C-clamp the way it could on an older car. Forcing it can damage the motor or the caliper mechanism.

The normal method is a scan tool with GM electronic parking brake functions, used to command the calipers to a retracted service position before the pads come out, then to apply and calibrate the system once the new pads are in. Work with a healthy battery or a charger connected, since the owner's manual notes the EPB cannot apply or release without sufficient electrical power. If you do not have a tool that can command the EPB, this is the half of the job worth leaving to a shop.

When replacing rear parts, do the same hardware and slide-pin service as the front, and replace rotors in pairs when needed. If a rear caliper is sticking or its EPB motor has failed, see replacement brake calipers.

Frequently Asked Questions

Do I have to replace front and rear brakes at the same time on a LaCrosse?

No. Front and rear wear at different rates, and most LaCrosse owners replace front pads before the rears need attention. Replace each axle when it is worn, and always do both sides of an axle together.

Do I need new rotors every time I change pads?

Not necessarily. The factory Duralife rotors resist corrosion and often outlast the first set of pads. Measure thickness against the minimum marked on the rotor and check for pulsation or deep grooves. If they pass, pads alone are fine.

Can I push the rear caliper pistons back without a scan tool?

You should not force them. The rear calipers contain the electric parking brake motor, and the piston needs to be retracted electronically before the pads can be replaced. Forcing it risks damaging the caliper or motor.

What brake fluid does a 2017-2019 LaCrosse use?

The owner's manual specifies DOT 3 brake fluid from a new, sealed container. Do not use mineral oil or other non-DOT 3 fluids, which can damage the hydraulic system.

Does the 2018-2019 eAssist model wear brakes differently?

The eAssist system recovers some energy during braking and coasting, which can take part of the load off the friction brakes in light stops. The front still wears first, and the service procedures are the same.

Are there any brake recalls on the 2017 LaCrosse?

NHTSA recall data for the 2017 LaCrosse lists campaigns for the electric power steering connectors and the rear suspension toe links, and none for the brake system. Check your own VIN on nhtsa.gov for the latest status.

Sources

1. Buick Introduces All-New 2017 LaCrosse (Automotive World) - four-wheel disc system, Duralife rotors, EBD, electronic parking brake, Auto Hold
2. Light Electrification Leads 2018 Buick LaCrosse Updates (Automotive World) - 2.5L eAssist standard for 2018, regenerative braking
3. GM Process for Better Brakes (Gardner Web) - FNC rotor process, corrosion and pulsation, rotor life figure, LaCrosse usage
4. 2017 Buick LaCrosse Owner's Manual, Electric Parking Brake - EPB operation, warning lights, electrical power requirement
5. Buick LaCrosse Owner's Manual, Brake Fluid - DOT 3 fluid, do not top off, low fluid can indicate worn linings
6. NHTSA Recalls, 2017 Buick LaCrosse - campaigns 17V116000 and 17V267000, none brake related