What Causes the Noise When Braking in Reverse?

[DiAva]

Reasons for noise when braking in reverse: When braking in reverse, which is opposite to the vehicle's forward direction, there is a certain amount of clearance between the brake pads and the rear end of the bracket. Therefore, during braking, the brake pads impact the rear surface of the bracket, resulting in abnormal noise. The working principle of braking mainly relies on friction. By utilizing the friction between the brake pads and the brake discs, as well as between the tires and the ground, the kinetic energy of the moving vehicle is converted into heat energy through friction, bringing the car to a stop. To mitigate the noise when braking in reverse, a thin layer of lubricating grease can be applied to the parts where the brake pads connect with the brake caliper bracket. This can help improve the phenomenon to some extent.

[MollyDella]

I know this issue all too well, having fixed cars for over a decade. That squeaking sound when braking in reverse? Eighty percent chance it's due to metal hard spots on the brake pads, most noticeable during cold starts. It's like having a pebble stuck in your shoe sole—when reversing, the brake pads rub in the opposite direction, causing metal debris to grind against the brake disc, hence the noise. It’s especially louder the morning after rain because a thin layer of rust forms on the brake disc, but a few more brake applications usually quiet it down. If it’s a sharp metal-on-metal scraping sound, check the brake pad thickness immediately—don’t delay replacing them if needed. Last time, my neighbor’s car had worn-down warning pads grinding against the disc, squeaking so loud the whole neighborhood turned their heads during reverse. A pad replacement only cost a little over 300 bucks.

[SanCameron]

Reverse braking noise is often related to metal contact. Brake pads containing metal particles wear in a fixed direction during normal forward driving, while reverse friction causes the metal particles to stand up and scrape the rotor. Another possibility is poor caliper retraction, where lack of lubrication on guide pins prevents the brake pads from fully retracting, causing no noise when moving forward but squeaking when reversing as the pads drag. This happened to my car last time—applying some specialized grease to the guide pins fixed it. If you hear a clicking noise when reversing the day after rain, it's normal; the rust will wear off.

[RiverFitz]

Encountered similar situations before. The high-pitched noise when lightly braking in reverse is usually caused by moisture changes in the braking system. Especially with aluminum brake discs, they tend to absorb moisture and oxidize, forming rust spots at the contact points with brake pads when parked. The first brake application when reversing will then produce friction noise. This is more common after rain or car washing, and usually disappears after several brake applications. However, if there's persistent high-frequency squealing, be alert for excessive brake pad wear where the metal wear indicator on the back has contacted the brake disc - this situation requires immediate brake pad replacement.