Why do my brakes squeal?

[Deuce]

Trying to work out what causes the noise.
Car is a 2007 epica, single piston front brakes.

Changed front pads a couple years back to cheap repco pads and not long later (week or two) it started making a noise. We tryed coppercoat on the pad/caliper contact areas, that didn't work so ignored it for a while but finally decided to do something last month.
Gave front disc surfaces an 80grit wherever they looked hot spotted.
That didn't work, so yesterday fitted new pads and disc's. I used the supplied lube for pad/caliper contact areas, also sprayed lithium grease on the slide pins.
All back together and still a noise.

My next plan is to investigate the rear discs and say the timing of the noise was coincidental. Or a brake fluid flush, but can't justify how that was the cause (I understand it was disturbed during pad change, but loose crud jamming somewhere maybe?)

Anyway, any thoughts or ideas appreciated.

 

[losh1971]

I was of the understanding that squeal is caused by cheap pads.

 

[greenacc]

Yep often cheap nasty pads, or dirty rusty rotors from lack of use, pad wobbling in calliper, uneven pressure on the pads like with dry slides or rusty calliper pistons.
If you are capable it might be worth popping the pistons out and checking they're not rusted.
I like pastey grease better than spray types.. It needs to be solid enough to stop vibrations.

Permatex Ceramic Extreme Brake Parts Lubricant 236ml

A 100% synthetic formula, coupled with real ceramic solids make this premium brake lubricant long lasting Most temperature resistant way to silence brake noise Ideal for Caliper pins, hardware, and the backside of brake pads, guide pins, disc brake pads Made in USA.

www.automegastore.com.au

 

[Drawnnite]

Do they only squeal when you press the brake pedal?
That could be the cause of the problem, just dont press it and it wont make noise
*Dont actually follow that advice*

Have you actually used them in a bit of anger at all?
One of the rears on one of the cars have a bit of a squeal when cold and not used (standard set), but goes away if i get on them a bit.
Same as another car, gets a bit noisy but goes away if used a bit (DBA T3s).

You also say you sanded them a bit, did you also spray and wipe away any excesses?
Not to be silly, but have noticed on bikes poor maintenance and types of pads can cause more noise.

 

[Deuce]

I was of the understanding that squeal is caused by cheap pads.

I had thought that, but new pads and disc's and no fix so hmmm

 

[Deuce]

Yep often cheap nasty pads, or dirty rusty rotors from lack of use, pad wobbling in calliper, uneven pressure on the pads like with dry slides or rusty calliper pistons.
If you are capable it might be worth popping the pistons out and checking they're not rusted.
I like pastey grease better than spray types.. It needs to be solid enough to stop vibrations.

http://[URL]https://www.automegasto...NiJPwTO-1H8YTv43jwexWoGbQYikBvfxoC17QQAvD_BwE

[/URL]

Yeah maybe pistons out and a bleed might be my next best bet.

 

[Deuce]

Do they only squeal when you press the brake pedal?
That could be the cause of the problem, just dont press it and it wont make noise
*Dont actually follow that advice*

Have you actually used them in a bit of anger at all?
One of the rears on one of the cars have a bit of a squeal when cold and not used (standard set), but goes away if i get on them a bit.
Same as another car, gets a bit noisy but goes away if used a bit (DBA T3s).

You also say you sanded them a bit, did you also spray and wipe away any excesses?
Not to be silly, but have noticed on bikes poor maintenance and types of pads can cause more noise.

No noise on light pedal. No noise on heavy pedal. Just medium pedal like most common braking.
Was going to try not using pedal ever, but had second thoughts about crashing and dying (*just kidding, never considered this)

I don't think we really drive the car in anger, as it usually has the kids in it too, and the V8 actually goes good on throttle, unlike this.

Yes cleaned after sanding, but also irrelevant since new pads and disc's and still noise.

 

[gossie]

You do need to go out and drive the car hard and fast with lots of heavy braking.

 

[VS 5.0]

Did you do a good bed in of the new pads and rotors ?

 

[Deuce]

Did you do a good bed in of the new pads and rotors ?

Yes I did.
30km/h x3
50km/h x3
80km/h x3