NHC MOTORS · SERVICE RECORD

BMW X7 40i Front Brake Pad, Disc and Wear Sensor Replacement

We replaced the front pads and discs on this 2023 X7 40i with new parts. We also replaced the pad wear sensor and applied a three-part brake-noise prevention set.

Front brake disc and pads after removal.

2023 BMW X7 40i

When brake pads are due for replacement, you may wonder whether the discs need replacing too. During a brake inspection, we check pad wear and disc condition separately. This helps determine which parts need replacing.

On this 2023 BMW X7 40i, we replaced the front pads, discs and wear sensor. We also checked the hub face the new discs seat against and applied noise-prevention treatment to the backs of the pads.

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We check the discs as well as the pads

We removed the front pads and discs and inspected the friction-material side of the pads and the friction surfaces of the discs. On the pads, we check how much friction material remains and whether it has worn unevenly to one side. On the discs, we check the condition of the friction surface and look for damage.

Pads are consumables that wear faster than discs, so discs do not need replacing every time the pads are changed. To decide whether a disc can stay in service, we measure its actual thickness against the limit value and separately check the surface for grooves or distortion that can cause vibration. On this X7, both the front pads and discs were replaced with new parts.

Friction-material side of a removed pad. We check the remaining thickness and wear pattern.

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Checking the hub face before fitting the new discs

With the disc removed, we inspected the hub mounting face. Rust or debris on this face can stop a new disc from seating evenly. That is why the contact surface needs checking even when new parts are going on.

We applied a three-part brake-noise prevention set to the backs of the new pads to reduce fine vibration where the pads and calipers meet. We kept it off the friction surfaces that contact the discs.

Hub mounting face exposed after removing the disc. This is where the new disc seats.

Applying noise-prevention treatment to the back of a new pad.

Pad back after the three-part brake-noise prevention set was applied.

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Pads, discs and wear sensor replaced

We fitted the new front discs to the hubs and installed the new pads, with their noise treatment complete, in the calipers. We also replaced the brake pad wear sensor.

The wear sensor signals when the pads have worn to a set point and are due for replacement.

New pads and discs need an initial period for their contact surfaces to bed in to each other. If you notice brake noise or vibration after the replacement, please let us know. Tell us the speed at which it appears and how hard you are pressing the pedal, and we will start by rechecking the hub mounting face and the fastening.

Three surfaces we check on the brakes

Pad friction material

Remaining material and wear pattern

Disc friction surface

Thickness, surface and damage

Hub mounting face

The contact surface the disc seats on

We check pad and disc condition together with the hub face the new disc seats against.

Frequently asked questions

Can I save money by replacing only the pads?

If disc thickness is within the limit and the surface has no deep grooves or distortion that causes vibration, the pads can be replaced on their own. If the discs are close to the limit or damaged, noise or vibration may remain even with new pads. That is why we measure the discs before deciding the replacement scope.

Should the wear sensor be replaced when the pads are changed?

The wear sensor wears down along with the pad, so it is often replaced at the same time as the pads. On this X7, we replaced the wear sensor together with the new front pads.

What if I feel vibration after new discs are fitted?

We first recheck the hub mounting face and the fastening. Depending on the speed at which the vibration appears and the braking conditions, we also check separately whether the wheels, tires or suspension are contributing.

Not sure whether to replace just the pads or the discs too?

We check the pads, discs and wear sensor, then explain what needs replacing. Please tell us the model, model year and mileage. If braking causes noise or vibration, mention the speed and conditions where it happens.

We explain the work and estimate before proceeding with your consent.

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031-258-1617 · NHC Motors, Suwon · By appointment

Published 2026-09-26