Knocking noise when Braking 2008 STI

[Darren]

I own a 2008 WRX STI. 

For the last 6 months or so I have had a knocking noise when breaking, I've had a mechanic look at it and he can't find the issue and set me back $2600 dollars.. he said it might be the lower sway arm but he can't find parts in New Zealand. He checked the bushes, bearings, breaks and calipers but the noise is still there! If I'm driving on the highway and break I can't hear it but if I'm pulling up to lights or intersections it's quite noticeable and bloody annoying.. any help or advice would be great as I don't want to sell it.. p.s I was told it's not an engine knock.

 

 

[Andy_Mac]

Is it like a single knock as something moves forward when you brake or a repeated knock/clunk when doing so?

[Loren]

Does it do it if you just coast to a stop without braking?

What about if you use the handbrake to stop?

[Gripless]

Ok…

what type of knocking?

is it a single big knock or bouncing knock knock 

does it sound sharp and harsh or more dampened and springy

 

is it only under braking or can it happen going over small speed bumps at low speed.

 

does it come from the middle or sides of the car?

with a passenger in the back seat so they can put their head out the window each side and tell which is louder. Go over a speed bump forwards then backwards. 
 

turn the wheels and look at the lower alloy arm rear rubber bush for cracks. Phone camera will show cracks better than you can see.

a tire iron or crow bar applying a bit of force under then can show cracks better.

its a common failure on the 2007-2013 until them swapped to ball joints. Whiteline did do balljoints for Motorsport use that pretty much like factory ones.

 

 

bushes are reasonably easy to get eg BNT or others have replacements

https://whiteline.com.au/search/popular-parts-for-subaru-impreza-2008-wrx-sti-gr-hatch/front-control-arm-lower-inner-rear-bushing-double-offset-kit-to-suit-subaru-forester-impreza-lib-9986-kca334.html
 

https://whiteline.com.au/search/popular-parts-for-subaru-impreza-2008-wrx-sti-gr-hatch/front-control-arm-lower-inner-rear-bushing-kit-to-suit-subaru-forester-impreza-liberty-outback-9986-w53353.html