knocking from front end

[lazzaman]

realize this is probably a common question on here and have checked through the search results but nothing matches my problem that i can see.
i have an 97 a4 avant with a knocking sound coming from the front end somewhere .
it occurs mostly when braking but also on certain pot holes or bumps and sometimes when changing gear .
i can make the knock by tapping the brake pedal whilst the car is slowly moving,it always knocks twice ,once for brake on and again for brake off.
ive had a good look at the front suspension and tried all the joints and bushes with a pry bar and cant detect any excessive movement or wear,ive also changed one of the engine mounts as this seemed weak but its still there and is slowly getting louder and more frequent .
i dont want to start replacing parts on a trial and error basis because it could get very expensive but im kinda hating driving the car because of it and need to get it sorted before something drops off .
i was thinking it could be subframe related as it seems to be coming from under my feet but again theres no obvious wear on the bushes.
any help sorting this would be greatly appreciated as someone must have had a similar problem in the past.
cheers
dazza

 

[filipharvey]

It'll most probably be the lower control arm on the suspension as these are prone to go. Mine failed (rather embarasingly) last week, after some time knocking whilst braking etc. Not something I would want to repeat!

Fairly cheap part to buy to £30-£60 depending on quality.

(Part No. 42230 (Normal Quality) / 42230A (Best Quality) at German Swedish & French)

 

[Turbo Lag FTW]

I have same kind of noise when i brake, also does it when I shove the car in reverse. Would it be the same problem?

I`ll prob take mine into my local Audi specialist to see if they diagnose the same and get a quote while im there.

 

[PaulJC84]

Turbo Lags with the braking may be the brake pads moving in the caliper.

 

[lazzaman]

mine does the same when lifting the clutch in reverse and sometimes 1st to 2nd when turning on roundabouts etc ,so it could be the same problem

 

[jcb]

control arm bushes or ball joint

 

[filipharvey]

I would say by your follow-up lazzaman, that its 99% the control arm. The knocking is caused when the weight of the car is shifted to or from the suspension on that side/end of the car.
Whether you can change the bushes, I don't know, but the arm itself which includes them is cheap enough, so I would (and did) replace the whole thing!

 

[98 A4]

The same knocking noise is coming from the front of my car too and when i back up it sounds like somthing is grinding when i apply pressure to the brakes.

 

[lazzaman]

mine doesn't grind just clonks,a bit like the sound you would get with a knackered engine mount, it also doesn't knock when transferring weight from side to side but more forwards and backwards .for example it wont knock over a speedbump but will knock like hell going up a drop kerb or rough road surface.
has anyone had any experiance of knackered subframes on the a4 coz if not i guess ive gotta start replacing arms one by one and hope i get lucky .

 

[scrupes]

it's deffo one or two of them m8, I recently changed all of them in one go cos i was sick of changing one at a time usually for an mot or with an inspection service, it's a much better car now!
i opted for a set of all arms, "c" links and track rod ends from ebay £165 delivered from germany! which when coupled with a garage fitting charge of £150.00 isnt too bad. but seeing as the car needed to have the front suspension off i chose to change the springs and shockers for a Weitec suspension kit.

if you can afford to, change the lot. if you cant, start with the bottom arms first, then the top arms. in my experience that appears to be the way they wear out?

 

[lazzaman]

cheers scrupes .
i thought i was going to have to weigh out about £500 just for parts ,if the kits are avalible for that little i may as well change the lot.
do you have a link for the ebay seller and whats the quality like???