Squeal when reversing

[ksin87]

Hi all! My first post on this forum as I'm in the market for a CX5 and was informed this is the best place to ask!

I recently test drove a CX5 2.5 Petrol GT Sport and noticed a high pitched constant squeak whilst reversing, which disappeared when pressing the brakes. There was no noise when driving forwards.

The front pads and rotors looked fine, but the rear pads/rotors looked a bit worn albeit still within limit.

Any ideas as to the potential cause of this noise?

Many thanks!

 

[ruthrj]

It could be as simple as some slight rust buildup on the rotors. I’d expect the squeal to go away though after some driving and braking around town. It never really happens to my vehicles which are garage kept, but if they are outside in high humidity for a period of time or there was some rainfall (or the car is sitting on a dealership lot), the brakes could squeak some until the rust is gone from normal braking.

I’d want to get the brakes looked at though to confirm their condition prior to purchase. I took for granted my “certified preowned” status on my truck which should mean brake pads are greater than 50% life left. I drive hundreds of miles home from where purchased the truck and find the rear pads are like 75% gone. Looked ok when I was scooting around under the truck but hard to eyeball pad depth and condition with the wheels on. No big deal but would’ve been nice to get those replaced prior to purchase.

 

[ksin87]

In that case wouldn't the noise be audible on forward movement too? It's only happening when reversing. Also, the car is being driven regularly as it's a private sale and there was no rust on the rotors at all on inspection. But I take your point, it's hard to inspect properly with the wheel on.

I just want to check if, from the symptoms, there is the possibility of a major issue, from your collective experiences!

Thanks!

 

[ruthrj]

In that case wouldn't the noise be audible on forward movement too? It's only happening when reversing. Also, the car is being driven regularly as it's a private sale and there was no rust on the rotors at all on inspection. But I take your point, it's hard to inspect properly with the wheel on.

I just want to check if, from the symptoms, there is the possibility of a major issue, from your collective experiences!

Thanks!

It’s possible, but I think you back up more slowly while in reverse. I doubt you’re taking your foot completely off the brake pedal while in reverse. Instead the pad is dragging slowly over the rotor and could cause a squeal. I tend not to hear a squeal from surface rust moving forward as the rotor is moving much faster, and then yeah I might hear a slight squealing noise as I slow from 5 to 0 miles and hour.

I’m spitballing though, a regularly driven vehicle shouldn’t do this. Maybe once in the morning if there was a lot of dew but it should clear up fast.

What model year are you looking at? There was a service bulletin for rear calipers sticking for a certain year but that was some time back.

 

[N7turbo]

Many rear brake squeals only happen in reverse. But they also tend to happen when the brakes are applied, which is opposite of what is being stated here.

 

[ruthrj]

Many rear brake squeals only happen in reverse. But they also tend to happen when the brakes are applied, which is opposite of what is being stated here.

Bingo, that’s what I’m thinking. When I back up my foot is still applying some pressure on the brake pedal. I rarely full send and take my foot completely off. Reapplying full pressure would stop the squeal if there was some light surface rust.

 

[ksin87]

Hmm, come to think of it, I think you may be right in that I wouldn't have completely taken my foot off the brake . I think I will have to try it again and be more conscious of what I'm actually doing!! It's a 2021 I'm looking at.