On going knocking noise....

[fran-s3]

Hey guys!

Very frustrating issue, thought I'd solved it but it seems not. Having some 'knocking' noise (very metalic sounding) coming from the front I think.. It's quite a fast knocking noise, almost like a vibration. No steering judder or weird handling when it does. (always hard to tell but I'm 90% sure it's from the front and on my side) only on rough road surfaces. Not on humps, just when the road is uneven.

So usual suspects were front bushes which after inspection were indeed truly knackered. As I took them off as I noticed my driver side front ARB sleeve had massive cracks in it! So I though right I bet that's it... So after finally replacing the front ARB (with an OEM one which they've changed the desgin, has no sleeves now) and front bushes it certainly helped the problem. But it still knocks! Had it checked and there's nothing obvious that's wearing, anyone had a similar experience which wasn't the ARB or bushes? Dam flipping S3, can't afford to keep doing this! Guess it's 9 year old suspension starting to give up!

 

[Westy]

I had a vibration that sounded like it was coming from the passeger side at the front an would only come on when I was under 15mph. It turned out to be where one of my wheel speed sensors was faulty and couldn't register speeds under 15mph so would engage the ABS pump. The pump would vibrate but didn't activate the brakes.

It doesn't sound like yours is anything like the same as mine but as you have nothing else to check it might be worth checking the wheel speed sensors on VAGCOM.

 

[fran-s3]

Thanks for that. Hmm no I don't think it's that either as mine isn't speed dependant at all and rarely does it at slow speeds like that. I would have had a check though if I had VAG-COM but I don't.

 

[tompearson]

A shock went on my old car and it used to make a knocking sound under load - this was most noticeable when cornering hard.

 

[NHN]

Top mounts would be a consideration, you'd be amazed what they do.

 

[fran-s3]

Thanks everyone for your replies.
NHN, easy to diagnose and replace?

 

[Sandip]

I had a knocking that lasted nearly two years, anti roll bar bushes changed twice, top mounts, drop links, balls joints in the end the knocking went when i changed my shocks and springs. I think your shocks are tired, the ride on mine was very harsh before i had them changed

 

[Westy]

That's a good shout as my shocks clunk when hitting bumps.

 

[fran-s3]

Cool thanks guys. I know it's impossible to describe noises but when you say 'clunk' do you mean a continious clunking or just one 'clunk' or 'bang'. As mine is more of a rattley clunk... ie lots of tiny clunks a second, almost like a vibration if that makes any sense lol?! (it's Monday!)

 

[S3 Nattie]

Sounds like your shock or shocks are gone. I had similar thing as what your saying on my previous cars. Got worse over time. Try going down a bumpy hill while applying the brakes, if the noise your hearing get more frequent I would say its your shocks.

 

[ianysm]

I had two similar experiences. One was due to the alloy wheel centre caps being loose!!! I popped abit of blue tack in there which has lasted ages so far!

The other was worn front anti roll bar and bushes

 

[Westy]

Cool thanks guys. I know it's impossible to describe noises but when you say 'clunk' do you mean a continious clunking or just one 'clunk' or 'bang'. As mine is more of a rattley clunk... ie lots of tiny clunks a second, almost like a vibration if that makes any sense lol?! (it's Monday!)

Mine is a clunk when I hit a pothole or bump not continuous and its a definite suspension clunk.

 

[tompearson]

When my shock went it was a continuous knock-knock-knock (or clunk-clunk-clunk)whilst it was under load. Not quick enough to be described as a vibration though. You could repeat the knocking by bouncing the relevant corner up and down although it took some effort. Having re-read your first post though I would have to say it wasn't really a metallic sound.

Do engine mounts go on S3's? A friend sheered his, in a golf I think, and that made an awful noise until he diagnosed it.

 

[fran-s3]

Thanks guys. Yes it's like a clunk clunk clunk tom, and now im thinking it could be the shock itself. Going to try bouncing it up and down with a mate and see if it re-creates the sound. That's a good idea... Are shocks expensive? Yeah apparently top mounts are common to. I just want to diagnose it correctly which is gonna be a ******! Doon't fancy paying for both! (shock and mount!)

 

[fran-s3]

Oh and question, do shock and top mount struts all have to be replaced in pairs? Can you get away with doing one side?