Light knocking noise from the chassis

TANKSLAPPER · 16-03-2009, 09:46 PM

I would appreciate your help.

I’ve got a light knocking noise which seems to come from the front end of the car, only when it has warmed up, the hotter it gets or the longer the run the noise is louder.

I can only hear the knocking when the car is freewheeling and slowing down in a straight line from about 35mph to 5mph ie with no load

The parts I have changed to try and rectify this problem are:-

Front suspension and top mounts
Front lower wishbone and rose joints
Front lower wishbone bushes
Engine and gearbox mounts
Rear trailing arm bushes with limiter kit
Exhaust mounting rubbers
Anti Roll bar drop links

The only other things I can think of changing is the steering rack , or the rear camber arms

SMD · 17-03-2009, 12:58 AM

Prop Shaft?

NZ_M3 · 17-03-2009, 01:05 AM

Describe the noise more .... i.e. is it a clanking sound? or metalic sort of a knock or a dull thud thud thud ...

It'll be a rotational related - so work from the wheels back and check every component from there on.

Given that it's not a load related noise you can rule out engine mounts and gearbox mounts.

Might be a wheel bearing, but these seem to rumble rather than knock.

TANKSLAPPER · 17-03-2009, 01:07 PM

Quote:

Originally Posted by NZ_M3

Describe the noise more .... i.e. is it a clanking sound? or metalic sort of a knock or a dull thud thud thud ...

Thanks for your response, I don't think it is the wheel bearing as this is a problem I have had for the past 30 months, and have traveled some 20,000 + miles since it occured

The sound is mainly heard around 20 mile an hour and it is more of a bobbling/bouncing dull knocking noise, and you can feel it on the near side when free wheeling

NZ_M3 · 17-03-2009, 01:38 PM

Check your tyres ... sounds like there's a flat spot on one of the tyres.

TANKSLAPPER · 17-03-2009, 01:46 PM

Quote:

Originally Posted by NZ_M3

Check your tyres ... sounds like there's a flat spot on one of the tyres.

No its not that, I had four set of tyres since the noise begun

bryce · 17-03-2009, 04:23 PM

Quote:

Originally Posted by TANKSLAPPER

The sound is mainly heard around 20 mile an hour and it is more of a bobbling/bouncing dull knocking noise, and you can feel it on the near side when free wheeling

Does it do it if the car is out of gear? are you familiar with the knocking noise you get with SMG at lower speeds?

Video / sound clip would be good buts its always hard to capture these noises.

16-03-2009, 09:46 PM	#1
TANKSLAPPER S5, Sport Off, DSC M-track Join Date: Nov 2008 Posts: 801 Casino cash: $8979	Light knocking noise from the chassis I would appreciate your help. I’ve got a light knocking noise which seems to come from the front end of the car, only when it has warmed up, the hotter it gets or the longer the run the noise is louder. I can only hear the knocking when the car is freewheeling and slowing down in a straight line from about 35mph to 5mph ie with no load The parts I have changed to try and rectify this problem are:- Front suspension and top mounts Front lower wishbone and rose joints Front lower wishbone bushes Engine and gearbox mounts Rear trailing arm bushes with limiter kit Exhaust mounting rubbers Anti Roll bar drop links The only other things I can think of changing is the steering rack , or the rear camber arms

17-03-2009, 12:58 AM	#2
SMD S6, Sport On, Traction Off Join Date: Jun 2008 Location: Shropshire Posts: 1,505 Casino cash: $10726	Prop Shaft?

17-03-2009, 01:05 AM	#3
NZ_M3 S5, Sport On, DSC M-track Join Date: Jun 2008 Location: Auckland, New Zealand Posts: 1,434 Casino cash: $13579	Describe the noise more .... i.e. is it a clanking sound? or metalic sort of a knock or a dull thud thud thud ... It'll be a rotational related - so work from the wheels back and check every component from there on. Given that it's not a load related noise you can rule out engine mounts and gearbox mounts. Might be a wheel bearing, but these seem to rumble rather than knock.

17-03-2009, 01:38 PM	#5
NZ_M3 S5, Sport On, DSC M-track Join Date: Jun 2008 Location: Auckland, New Zealand Posts: 1,434 Casino cash: $13579	Check your tyres ... sounds like there's a flat spot on one of the tyres.