Annoying brake squeal

[Bobton125]

Just recently replaced my front pads and discs due to needing a caliper changing too

The pads were actually alright as I only fit them last year.

Using the same brand pads and discs as I used before and I greased the back of the pads and ends that slide with mintex ceramic grease but I’m now getting Brahe squeal only at speeds more than around 30mph

Any idea why this is, what actually causes the squeal?

Changed my own discs and pads hundreds of times and didn’t do anything differently, wondering why it’s started doing it now everything’s new

Any suggestions??

Car is a 2013 Kia ceed

[littleredrooster]

Squeal is caused when the static coefficient of friction exceeds the dynamic coefficient of friction. This causes the the pad(s) to move back and forward very rapidly (within the tiny amount of clearance they have), setting up a resonance somewhere in the caliper.

The trick to getting rid of it is to change something. Anything. If it has shims, try it without. If it doesn't have shims, put some in. Grease/no grease. Swap the pads left to right and bed them in again. Sometimes even removing and re-torquing the caliper bolts works.

Good luck

[Smint]

Thoroughly covered by the previous poster.

Couple of thoughts, did you thoroughly clean and regrease any sliders, also you mention one caliper change, not two?
The caliper staying put; did you ping any spring clips that the pads sit in from said caliper(s) and throughly scrape clean where the clips sit, sharp chisel, wire brush etc, a lot of crud can get stuck behind those clips which needs to come out.

[Bobton125]

The other caliper was replaced 6 months back.
Yep sliders greased. Clips where the pads slide on cleaned. There are no other spring clips/retaining clips

[Smint]

Ok, have you removed the pads and closely examined all non friction material points of contact, where the pad is vibrating as eloquently described above it usually leaves a clean highly polished point, hopefully two points.

Don't often get squealing but it can take some pinpointing when you do get it.

[GreenV8S]

Bobton125 said:

Any suggestions??

You need to change the resonant frequency of whichever bit is squealing. It's more of an art than a science imo, but here are some techniques which have worked for me in the past:

• Confirm all bolts are secured, all clips fitted, no dirt on any contact / bearing surfaces
• Add an anti-squeal shim (damping pad)
• Remove the anti-squeal shim
• Regrease the sliders
• File a bevel on the leading and trailing edges of the pads

I would usually go through the list until the problem goes away.

[TallPaul]

I’ve had constant squeal, caused by the friction material delaminating from the backing plate. Main symptoms were squealing/whistling occurring when driving which went away when applying the brakes. The friction material was resonating against the backing plate.
Obviously its different to the more common squeal when pressing the brake pedal which the posters above have covered but could be worth a look.

[E-bmw]

TallPaul said:

I’ve had constant squeal, The friction material was resonating against the backing plate.

I find it hard to believe that the friction material was resonating against the backing plate as they are bonded to each other.

[GreenV8S]

E-bmw said:

they are bonded to each other.

Not if they're delaminated.

[TallPaul]

E-bmw said:

I find it hard to believe that the friction material was resonating against the backing plate as they are bonded to each other.

[E-bmw]

TallPaul said:

E-bmw said:

I find it hard to believe that the friction material was resonating against the backing plate as they are bonded to each other.

I stand corrected, never seen that in all my 40+ years of working on cars/bikes.

[TallPaul]

They were “branded” pads, may have even been Motorcraft but I found them cheap on ebay, most likely fake copies. That’ll teach me to think I’ve found a bargain!
I’ve seen it a few times with poor quality products, I guess they use an inferior bonding process.