Rear knocking - Not DRC

[RS4ABM]

Hi Guys,

I have had a good look around this forum for the answer to my knocking problem but im having no luck!!

A year ago the DRC setup was removed and I installed KW V3. About 4 months ago the the rear passenger side started to create random knocks/rattles when driving over not so well maintained roads. Recently it happens a lot more and the other side has started to join in.
Ive had the car in the air and removed the shock to check that which seems to be fine, ive replaced the anti roll bar drop links too but no change.

The noise sounds metal on metal but I cant see that any of the bushes under the car are warn at all, so this leaves me confused.

I hope someone may have come across this before?

Thanks in advance

[adsgreen]

Could it be the spring bashing against the shock when unloaded?

[coffey555]

Mounting bushes on the rear anti-roll bar? Did you remove the old drc pipework when you had the KW3 kit fitted?

[sonny]

Are you 100% its coming from the rear? Get someone to stand by the road and drive past, so they can hear it from the outside.

Steering rack can be prone to knocking, however that will be pretty obvious.

Have you checked the exhaust mounts and rear anti roll bar bushes?

Only time I have heard of knocking coilovers is then the inside rod rattles on the inside of the strut, however again this will be pretty obvious as the fluid/gas would have been expelled.

[Batfinnk]

Might sound a bit random but check the supports on the rear bumper. One of the rivets has come loose on mine and it makes quite a pronounced rattle/ clanking over bumps.

[RS4ABM]

It definitely a strange one,
Adsgreen - I haven't looked into the spring hitting the shock yet! is that possible on the rear?

Coffey555 - I did have a look at the anti roll bar mounting bushes and they look to be in good shape, however I didn't have them completely out? may be worth a shot! I did notice that the roll bar drop links were not the snuggest fit in the roll bar, however they did tighten up ok! could that cause a problem?

Sonny - Its 100% from the rear of the car, and very noticeable with the rear seats folded down. It is the same kind of sound the DRC makes when its faulty, Tap tap rattle rattle!

Batfinnk - The bumper is coming off this week so I will take a look at that too.

I appreciate the help guys, I will get to the bottom of this

[sonny]

Strange... Is it a saloon/avant/cab?

You have checked the inside of the boot for anything rattling around?

[RS4ABM]

Its a Saloon. Nothing rolling around, you can distinctively tell which side its coming from and when too.

I want to say its a shock failing but would surprise me that both V3 would fail after 5k miles of use!

I didn't remove all of the DRC pipework when I fitted the V3 but I cant see that causing issues could it?

[sonny]

Only real way to check would be to get the car jacked up... The pipe work may well make the noise. Have you checked the rubber grommets that the springs sit on? I had one of these replaces on my saloon as the spring shifted and the open coil was biting into the rubber causing it to perish.

Likewise a lose ARB bolt can make a loud knocking noise (arb hitting droplink) i would def check these again.

[RS4ABM]

I still cant get to the bottom of this, Is there any chance that the ARB could have warn out? Reason I say this is when fitting the new drop links they didn't seem to fit very snug inside the ARB!
I may remove the drop links and take it for a spin, carefully of course!

[mf51y]

Check the clearance around your Milltek, there are a few places where if not fiited correctly or if its moved it could catch.

[watts6087]

I know its sounds simple but have u put the bit of plastic on
Top of the spring it comes with the coilovers !
Worth looking at

[sonny]

Only real way is to put sound sensors under the car and check where its coming from.

[taylora]

double check the exhaust mounting brackets.
on my old m3 they had broken one one side. or at least the metal inside them had broken, but the rubber mounts looked okay - at first.
this meant the exhaust was going up and down much more than it should at one side at the back, hence clonking into the underside.

the brackets had 2 levels of reinforcement and i think from memory only one of them had gone so it was flexing much more than normal but not completely had it.
probably isn't this, but worth a check anyhow if you are under there.

[Paddyleigh]

Had a similar noise with my Avant.. to begin with sounded like one side intermittently then after a while got worse then would appear to get better. Lots of tooing and froing to garage. Turned out to be the centre bearing on the propshaft!

New prop fitted..jobs a good'un