Brake 'groaning' noise

[Andrew162]

I have upgraded my standard discs to DBA's a while ago now, had the pads changed over about 5000km ago and they still have good meat on them. On moderate to hard braking (like red light camera-style pulling up at lights), I hear a groaning noise coming from somewhere in the braking system. Brake fluid is topped, no apparent problems with the brake booster, and it doesn't happen with soft braking.

Any ideas?

[oldcorollas]

I have upgraded my standard discs to DBA's a while ago now, had the pads changed over about 5000km ago and they still have good meat on them. On moderate to hard braking (like red light camera-style pulling up at lights), I hear a groaning noise coming from somewhere in the braking system. Brake fluid is topped, no apparent problems with the brake booster, and it doesn't happen with soft braking.

Any ideas?

do you have an even covering of pad material on the discs? ie even colour?
what pads are you using?

[Andrew162]

I'm using QFM Semi-metallic's...

Do you mean if I have concentric lines around the disc surface, like uneven wear?

[Joorsh]

You'll find if they are slotted they will make a bit more noise than standard brakes under heavy load. I know I was surprised at the noise my brakes made coming down hard from 100kmhr for the M2 toll booths - like you described - a kind of groaning noise. I asked the RDA blokes about it, and apparently it's just something that hard pads and slotted discs will do. The noise isn't really loud or anything, but you do notice it if it's quiet in the cabin.

[Andrew162]

I don't know, but I think this might be a different type of groan that you describe. I think I know what type of groaning you mean, like the slotted surface rubbing against the pads to cause the groan... I've had the discs for over 2 years and I've done some hard braking in them before, but I've never heard (or felt) anything like this. I can kind of feel it through the brake pedal when it happens.

[oldcorollas]

I don't know, but I think this might be a different type of groan that you describe. I think I know what type of groaning you mean, like the slotted surface rubbing against the pads to cause the groan... I've had the discs for over 2 years and I've done some hard braking in them before, but I've never heard (or felt) anything like this. I can kind of feel it through the brake pedal when it happens.

ahh, if you can feel it in the pedal, i'd be betting there is some uneven pad material on the brake disc... if you could be bothered, give them a go-over with emery paper/similar, and see if it goes away..

[EldarO]

Bah, who needs brakes, get rid of them, and you wont have any groaning noises at all!

Eldar.O.

[gianttomato]

Check to see if there is any material deposition on the pads. You should see some darkish colored stuff behind the leading edge of the slots. If you do, emery paper as per Stu is one solution. The other option is to give the brakes quite few hard stops in a row.

Also sometimes, change pads as certain pad-rotor combos are very bad for this (eg Greenstuff and DBA rotors).

[Andrew162]

I'll check out the pads and discs today to see what's going on. I just hope it's something easy-fixable, because I don't want anything to be wrong with the brake lines and booster, etc.

[wagonist]

Have you ever cleaned out the slots in the discs?
I had a slight shuddering too until I did that the first time, as the slots had completely built up with brake dust.
The groaning noise sounds like the normal slotted disc noise, but without hearing it, no one on hereis going to be able to give you a definite answer.
I'd suggest going to a brake shop & ask them to come for a test drive.

[Andrew162]

Yep, definitely Steve... That was going to be my next move.