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Not much information to go on so I will ask, how are your brake pads?
Could be a wheel bearing on it's way out or worn suspension. Have even found that after working on a car, if you don't do the sway bar link pins tight enough it can cause noise under braking. Have you worked on the front end lately?
Has the noise only started since Holden working on it?Not myself but holden changed out suspension bushings and tie rod end
This rarely happens but when it does it makes a strange shhhhhh gerrr sound when i press down on the brakes??
Has the noise only started since Holden working on it?
One quick check is while the car is on the ground, get under the front near the wheel on each side and try and grab the sway bar link pins and wiggle them around to see if they are loose. If too hard, drive the front wheels up onto a couple blocks of wood or something to give you more room to get underneath the car. The front wheels have to be on the ground taking the weight of the car for this to work........a sloped driveway maybe. Anything that will give you clearance under the car
Seriously doubt it'd be link pins.....Worn link pins rattle when hitting bumps as well, not just under braking.....It's quite possible either the slide pins in the calipers are starting to sieze up, or maybe even the booster is starting to go....To check the booster, start the car and before driving off, pump the pedal a few times and see if you can hear noises from that. Look for signs of brake pad material on the rotors....This is a sign the slide pins are seizing up in the calipers.....2nd thoughts, grease them up anyways....This can only be beneficial anyways.
There's a few starting items