Braking System

No, though an MoT inspection would pick up any problems.

You took the thought right out of my head.

We'll be right, _{or wrong} together.

Thanks,

Lyn

GA... or possibly Cat under bonnet
Del

"Cat under bonnet"

_{Car drives off, trailing cat fur. Broken cross bow falls from car}

Thanks,

Lyn

if no problem in braking system check wheel bearing, it may defect

It might help to know what type of noise, such as squeak, hiss, knock, etc., you are hearing, in order for us to offer our best guess, as the cause.

Yeah, please post a picture of the noise.
That's no so daft, I s'pose you could post or link to a .wav file
Del

Try the "Little Old Lady" solution and just turn the radio up a notch.

If it does turn out that your pads and rotors have sufficient thickness, then you could have a problem with one of your calipers not fully retracting after releasing the brake. Just the slightest sticking can cause this. It would also explain why when you apply your brake the sound goes away, but then comes back.

Might be the answer, might not, but in any case I hope it helps

I would check the mufler bearings. Te He

Since the noise doesn't appear until you have gone 20 miles, I would rule out the annoying spring that OEMs put on the brake pads. When they start rubbing, they rub all the time, not just after going 20 miles. This sounds like some sort of friction that is causing a heat build up and expansion of metal. Maybe it is a dry wheel bearing. In any case, it needs to be checked by a certified mechanic that you trust. Good luck finding one of those.

G'day, Disk pads never fully release from the disk. They always rub lightly. Since it takes 20 miles or so to make a noise, this suggests expansion of the pads/piston/fluid is increasing the pressure on the disk-pad interface.

Check the anti-rattle clips/squeal shims behind the pads.

Spray some disk brake quieting goo on and around the pads. Should be available in car parts stores.

Check the master cylinder position when static. The return port for the fluid may be slightly covered by the piston or even partially blocked. A blocked return port has been known to lock brakes on as they get hot.

Worn pads will make a grinding sound when applied and will scour the disk and you'll most likely feel this through the pedal. It will not disappear when the brakes are applied.

I'd suggest checking the pad anti noise shims or clips first. This costs zilch.

Regards,

RRV

I am unfamiliar with the specific features of the Micra brakes but here are some general suggestions. First, does the noise come from the front or the back wheels? If the noise comes from the front and the front brakes are disc the caliper might have lost the anti-rattle spring which prevents the pads from moving when the brakes are not applied. The caliper parts have their smallest dimensions when they are cold but as they warm up after several applications of the brakes the pads may rattle. Get a copy of the parts diagram for the brakes (it appears in the factory shop manuals for the Micra and also in the on-line parts lists for that model from Micra dealers) and check that all parts in the diagram are present on your brakes. Given the age of the car I assume the front pads have been replaced at least once and the mechanic may have forgotten to reinstall those springs. If the noise comes from the rear and/or all brakes are drum, pull the wheel and look for a missing hold down spring.

Dennis Waller