Knocking sound and running out of ideas!

[Gratts]

Hello all,

My first post after reading many others on here regarding the seemingly common 'knocking noise' from the front of my S3.

Symptoms:
- I hear the knock when turning either left or right.
- Once it's knocked turning right, it won't do it again until turning left.
- It doesn't knock while repeatedly turning on the spot, so I ruled out steering rack (for now).
- If I move sharply from standstill (forward or reverse) with full lock, it knocks.
- While driving, I have to turn fairly sharp to make it knock, although a bump while turning gently seems to trigger the knock.
- The sound is low down, I can feel it through the steering wheel and both front footwells (so through the sub frame)

So basically it requires a certain amount of lateral movement before it will knock.

After reading several threads, I've replaced:
- Front anti roll bar & bushes, as the collars/sleeves had snapped. Fitted a Neuspeed bar with welded metal collars. No luck, so then...
- Top mounts.
- Lower ball joints.
- N/S track rod & end (for some reason there was a thinner A3 track rod fitted). O/S end & drop link also changed recently.
- N/S outer CV joint (this was making a seperate grinding noise, so needed replacing).

IT STILL KNOCKS!

Removed lower engine mount, no sign of excessive wear. No knock when lifting the clutch/changing gear, suggesting the mount is ok.
Removed both front lower arms and inspected bushes - no signs of wear/deterioration.

Does anyone have any ideas what it could be? I've run out of ideas! I need to get the tracking/camber sorted as so much has been replaced but would really like to get to the bottom of the problem before doing so/driving the car.

Thank you very much in advance and also for all the previous posts on this topic, much appreciated! :icon_thumright:

 

[Welly]

Hi mate, following on from your post on my thread, I am in the process of taking my engine out for other reasons. However I will have a good look around the back side of the engine whilst it's out to see if I can find the cause.

Nothing I have changed has made any difference to my knocking/clunk.

 

[Geoff-R]

Subframe torqued correctly?

 

[sportstractor]

- Top mounts.

when you did the top mounts, did you change the bearings?

 

[Dani_B19]

Would top mount bearings really cause that much noise though? Ive a got a horrendus knocking, is that loud you can hear it withthe window down and stereo on! Ive replaced every bush and bolt their is and even the garage cant find anything wrong, last thing todo is chanethe passeneger side coilie as we suspect it may be that!

 

[sportstractor]

Yeah they cause a fair bit of noise and rattles, mine sounded horrible after I went through a pothole and destroyed one

 

[Tooks]

A faulty or worn out damper could be causing the noise, definitely.

I had a 'Dominic The Donkey' braying noise on mine, I'd changed lower wishbones, drop links, top mounts (a spring cup was on upside down!), top mount bearings and still it was there. I suspected the rear suspension after a while, but changing the roll bar mounts on the front cured it, even though the ones on there didn't look that worn.

None of that would be the cause of your clunking, but the point is that I was surprised how much the noise travelled. I was convinced that it was from the rear in the end!

 

[andya3turbo]

As above theres a good chance it is a damper, i had a knock on an old Citroen ax once and it happiend on an audi 80 to when i jacked it up and rocked the wheel top and bottom it was there and that turned out to be the damper, the piston moving in the sleeve was so annoying

 

[L33h]

I had the same but it was knocking when i was pulling away aswell. Changed the gearbox mount and all was fine

 

[Gratts]

I will have a good look around the back side of the engine whilst it's out to see if I can find the cause.

Nothing I have changed has made any difference to my knocking/clunk.

Thanks Welly, best of luck with the rebuild!

 

[Gratts]

Subframe torqued correctly?

New subframe bolts arriving tomorrow, will torque those correctly and see what happens - hopefully it'll solve it, if not at least I can rule out a shifting subframe. I'll be fitting some of those subframe spacers/shims mentioned in another thread too.

 

[Gratts]

when you did the top mounts, did you change the bearings?

Sorry forgot to say I changed the bearings too.

 

[Gratts]

A faulty or worn out damper could be causing the noise, definitely.

If the new subframe bolts don't solve it, the dampers will be next on the list. Although when in the car the sound seems low/through the subframe but a knock/clunk on this level is going to transmit all over the car, as you said.

Thinking about it, the only time it's made the noise when the car hasn't been turning whilst moving is when it's being lowered back onto it's wheels from a ramp. It's only done this a couple of times and sounded like a loud metallic snapping noise. Springs are intact and seated correctly but could well be a damper as you say? Definitely next on the list.

Will try get hold of an old one to fit before buying a new pair, just to see if it solves the problem before parting with more £. If I do need to replace them, does anyone have any recommendations? I'll have a hunt around on the forum.

Thanks all for the suggestions on this.

 

[Gratts]

I've just fitted & torqued new subframe bolts, along with some of those VW spacers recommended on another thread... it still knocks

When I lowered the car back onto its wheels, I heard a noise from the top of the front wheel (so level with the body of the damper)... it sounded very metallic from the outside, more like a sharp snapping noise. Typically, I couldn't get it to repeat the noise by raising/lowering again. There seems to be no play at all in the damper when rocking from top to bottom but I guess the internals could still be damaged.

Back inside the car, it definitely sounds low down. Passengers can feel it in their footwell, I can feel it in driver's footwell. Once it's knocked turning left, it won't do it again until turning right. It doesn't do it on every turn, just the ones with 'enough' lateral load, e.g. if I turn sharply into/out of a T junction.

Do these symptoms still point to a damper? They're next on the list! Otherwise steering rack? It doesn't knock when turning on the spot, I've tried this several times, so I'm thinking try the dampers first?

Thanks in advance for any further suggestions, much appreciated :thumbsup:

 

[L33h]

Driveshaft

 

[lgooch]

Steering rack would be where I look next

 

[Gratts]

I replaced both front shocks, putting another big dent in the wallet... didn't solve the knock

Then I heard it once again when lowering off ramp. Sound was coming from centre of the hub. Only thing left to change on that side was the wheel bearing... NO MORE KNOCK!!

Has anyone heard of a knocking wheel bearing? I thought they made a humming sound. Mechanics I've spoken too seem surprised it was the bearing. Only knocked when cornering, once when turning right then not again until turning left. There was no play at all in the wheel/bearing before replacing but once the hub had removed, there was noticeable play in the bearing.

I then noticed a second, quieter, far less frequent knock. After more poking around under the car I noticed the corner of the transfer box had been catching one of the power steering pipes. There's plenty of clearance but the engine must move enough to make contact. The pipes are very rigid and I can't seem to alter their position enough, so I've cable tied some coolant hose around it for now. Seems to have stopped knock number 2 :icon_thumright:

 

[tommytonguedj]

Check this article out below off another site, Also as mentioned somewhere on this forum by i think turkster slide pins on the brakes solved it for one member. HTH Tommy

Clunking noise solved! - AudiWorld Forums