2012-2015 BMW X1 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on a 2012-2015 BMW X1 comes from one of three things. A squeal usually means pad vibration or dry hardware. A grinding sound usually means pads worn to the backing plate or a parking brake shoe dragging. A pulsation is almost always uneven rotor thickness, not a truly warped rotor. Each one feels different and has a different fix. In most cases the right answer is new pads and rotors, installed on a clean hub with properly lubricated hardware.

How the Brakes Work on the First-Generation X1

The 2012-2015 X1 (chassis code E84) sold in the US has disc brakes at all four corners. BMW's own parts diagrams for the X1 xDrive28i list a front brake disc, a rear brake disc, and separate brake pad wear sensors for the front and rear axles. The brakes get their power assist from a vacuum brake booster, and the car has a regular handbrake lever instead of an electronic parking brake.

The handbrake matters when you're tracking down noise. It doesn't clamp the rear pads. Instead, the lever pulls a cable to a small set of parking brake shoes that sit inside the hat of each rear rotor. BMW's parts catalog shows the shoes, an expanding lock, an adjusting screw and a spring kit in that assembly. If the shoes are out of adjustment or a spring is broken, they can drag or scrape inside the rotor even with the handbrake off.

Squeal: What It Means and How to Stop It

Squeal is vibration. Ferodo's brake noise guide sorts brake noise into three types: a low-frequency judder, a mid-frequency squeal and a high-frequency squeak. The usual causes of squeal are a sticky caliper piston or slide pins, missing or badly fitted anti-noise shims, pads installed the wrong way, or a rotor that is too thin or no longer flat. A very high-pitched squeak often comes from the pad material itself. The fix for that is a new pad set with the correct shims and hardware.

On an X1, check these before you replace anything:

• Slide pins and pad contact points: Dry or rusty slide pins let the pad sit crooked and vibrate. Take them out, clean them and lubricate them with brake grease.
• Shims and clips: A missing or shifted shim or a bent clip will chirp under light pedal pressure.
• Glazed pads: Overheated pads develop a hard, shiny surface that squeals. Replacing them is the reliable fix.
• Wear sensor: Some cars use a metal tab that squeals on purpose when the pads get thin. The X1 uses electronic sensors instead, so on this car worn pads usually show up as a dashboard warning, not a squeal.

Keep grease off the pad and rotor surfaces. Ferodo says clearly that no grease should touch the pad material. Once a pad is contaminated, it can't be cleaned back to normal.

Grinding: Worn Pads, Rust or the Parking Brake

A metal-on-metal grind is the one noise you should never keep driving on. On a first-generation X1 it usually has one of three causes:

1. Pads worn down to the steel backing plate. The wear sensor should warn you first. But if a sensor was unplugged, damaged or left off during an earlier brake job, you get no warning. Once steel touches the rotor, the rotor is scored and has to be replaced along with the pads.
2. Rust on the rotors after the car sits. A light scraping for the first few stops after rain or a car wash is just surface rust wearing off. If it goes away after a few stops, it's normal.
3. Dragging parking brake shoes. Suspect the shoes inside the rear rotor hat if you hear a scrape from the rear that keeps going with your foot off the brake, especially if it changes when you pull the handbrake lever. A broken spring or a stuck adjuster lets a shoe rub.

Also check for a stone or other debris caught between the rotor and the dust shield. That makes a steady scraping sound that doesn't change when you press the brake.

Pulsation: Why Rotors Feel Warped

A pulsing pedal or a shaking steering wheel when you brake comes from disc thickness variation (DTV): the rotor has worn thicker in some spots than others. The rotor has not bent. Brake and Front End explains that runout, the side-to-side wobble of a rotor as it spins, doesn't cause pulsation directly. It causes it over time. On every turn, the high spot of a wobbling rotor rubs the pad. That rubbing wears some areas of the rotor and builds up pad material on others, until the thickness is uneven. Drivers start to feel it at only about 10 to 20 microns of variation, which is thinner than a sheet of paper.

The same source says unibody vehicles with strut suspension, which includes the X1, feel pulsation more than body-on-frame vehicles do. That is one reason an X1 can develop a vibration within a year of a sloppy brake job.

These installation mistakes are the most common cause:

• Rust on the hub face. Wagner points out that even a small buildup of rust between the hub and rotor creates runout. Clean the hub face down to bare metal before you install a new rotor.
• Wheel bolts tightened unevenly. Brake and Front End reports that under-tightening just one lug can add as much as 0.003 inch of runout. The X1 uses wheel bolts. Tighten them in a star pattern with a torque wrench, not an impact gun, to the value in the factory service manual.
• Skipping the runout check. Measure runout with a dial indicator while the rotor is mounted, and compare it to the factory spec before the wheel goes back on.

Once DTV has set in, the fix is new rotors. If a rotor is at or near its minimum thickness, don't machine it; replace it. Put new pads on at the same time so uneven deposits from the old pads don't transfer to the new rotor surface. Our front drilled and slotted rotor pair for the 2012-2015 BMW X1 fits this car, and you can pair it with pads from our ceramic brake pad collection.

The Fix and What to Replace at the Same Time

For a noisy or pulsing X1, doing the whole axle at once gives the best result. Replace these together:

• Pads and rotors, in pairs, one axle at a time. Browse brake rotors and brake pads.
• Pad wear sensor. If the dash warned you or the sensor wire is worn through, put a new sensor on that axle. New pads with an old, damaged sensor will keep the warning on.
• Hardware. Install new clips and put fresh grease on the slide pins. See our brake hardware kits.
• Parking brake shoes if the rear rotors are coming off anyway and the shoes are thin, oil-soaked or have broken springs. You can only reach them with the rotor off.
• Brake fluid if it's due. BMW's Condition Based Service display tracks when the fluid is due. Follow that display and your owner's manual.

After installation, bed in the pads using the pad maker's procedure. Ferodo also recommends pumping the brake pedal before the first test drive so the pistons move back out against the pads.

How Hard Is the Job?

Front pads and rotors on an X1 are a moderate job for a home mechanic with a torque wrench, a caliper piston tool and a way to reset the service reminder. The rear axle adds the parking brake shoes and adjuster, which take more patience. To reset the brake pad service reminder afterward, you'll usually use the instrument cluster menu or a scan tool. If you're not confident measuring runout or adjusting the parking brake, have a shop handle those two steps.

Frequently Asked Questions

Why do my X1 brakes squeal only in the morning?

Overnight moisture leaves a thin layer of rust on the rotors. The first few stops scrape it off, and the noise goes away. If it keeps going after the brakes warm up, check the pads, shims and slide pins.

Can I just resurface my X1 rotors to fix the pulsation?

Only if the rotor will still be above its minimum thickness after machining. Many worn X1 rotors won't be. New rotors installed on a clean hub are the more reliable fix.

Do I need to replace the brake pad sensor every time?

Replace it any time it has set off a warning or the wire is damaged. If it never wore through and is in good condition, you can often reuse it.

Why does my X1 grind from the rear when the handbrake is released?

Most likely the parking brake shoes inside the rear rotor hat are dragging. The usual reasons are a broken spring or an adjuster that is set wrong or stuck. Take off the rear rotor to inspect them.

Are drilled and slotted rotors noisier than plain rotors?

They can make a light whirring sound under braking as the slots pass the pad. That is normal. They should not squeal or grind. If they do, check the pads and hardware.

Sources

1. BMW Parts Deal - 2013 X1 xDrive28i (E84) brake diagrams - E84 X1 brake layout: front and rear discs, separate front and rear pad sensors, handbrake lever, vacuum power brake unit
2. BMW Parts Deal - 2013 X1 parking brake / brake shoes - cable-operated parking brake shoes, adjusting screw and spring kit inside the rear brake
3. Brake and Front End - Top brake pulsation questions - DTV is the main cause of pulsation; one under-torqued lug can add 0.003 in of runout; rust between hub and rotor
4. Brake and Front End - Diagnosing pedal pulsation and vibration - mounted runout converts to DTV over time; drivers feel 10-20 microns; strut-suspension unibody vehicles are more sensitive
5. Wagner Brake - Pedal pulsation and disc thickness variation - hub rust causes runout; clean hub, measure runout, tighten lugs evenly
6. Ferodo - Brake noise technical tips - judder vs squeal vs squeak causes and fixes; clean and lubricate slides; no grease on friction material