Knocking on front end after 30 mins driving

[gojerry]

 I have  an 03 Boxster with 95k on the clock.

When you first start driving the car, everything is tight and quiet. After about 25 - 30 miles, the front start to knock lightly and rumble. Most noticeable between 0 and 30mph in queuing traffic.  You can feel the knocks on the steering wheel and brake pedal. The further you go the worse it gets. The sound is like a bolt being jarred in a plastic bottle.

Up to now it has had new bake disks and pads. Track rod ends and wishbones replaced and something That looks like coffin struts changed. Wheels and tyres have been checked. When the knocking started, the brake warning light came on. The front sensors have been changed so the warning lights don't come on when the knocking starts.

I am not mechanically minded but In my mind its a brake problem as the issue only shows up after driving for about 30 miles and things are starting to warm up.

The garage cannot identify the issue and have run out of ideas. Can anyone suggest or identify the problem as I have been replacing bits without success

[RFM]

Remember that, just like the brakes, the shock absorbers also warming up by the friction on the in and out movements. The fact that the wheel sensors are replaced remind me of weak shock absorbers, the sensors go thereto defect. 

[gojerry]

Thanks for the input. I will replace them for what they cost

[Terry-986-2.7-5spd]

Hi guys. Can you tell me if replacing the shock absorbers cured this problem please?  I have the very same issue which I am trying to resolve. 
Cheers,

Terry

[Terry-986-2.7-5spd]

Hi guys. Just thought I’d provide a further update with this issue in case you haven’t solved it. I ended up replacing the driver’s side tuning fork on mine with the upgraded EPS version. At first, this did not seem to solve the issue as it still kept knocking at slow speed after warming up. This only lasted for about 100km though and has been quiet since now for a few months. I’m still baffled by the problem as you would think that the replacement would immediately solve it if that part is the problem but it didn’t do this in my case. I’ll update this again if anything changes, but it’s quiet for the time being, touch wood!

 

cheers,

Terry