Audi A8 Front Suspension Knocking

[cityrecovery]

Hi,
not sure if anyones come across this, but I have a 53 registered Audi A8 4.0 TDI Quattro which has a knocking sound coming from the front suspension - all the bushes/control arms look recent & have been tested, but this sounds like top suspension mounts are lose - every time the suspension is rocked at speed - it rattles severly - just replaced bottom arms at the advice of a mechanic (£151.00 a piece) still no joy. The latest diagnosis is the shockers/gas suspension units are rattling on the inside - can this be the case even if the suspension raises & sets via the MMI button?
its done 200K miles, with full audi dealer history & no errors/fault codes being displayed

[towcestervag]

check top suspension arms with car on deck they wear and can show no signs when on ramp
also check the steering rack mounting bolts in pelham chamber

[a8 tech]

Over the years the best way I have found to pin point D3 suspension noises is to use chassis ears, the top arms do indeed present the most common failure however I have had issues with the front air suspension struts and also the lower C links but instead of guessing and replacing as you go try the suggestion.

One other problem found is the lower arm subframe bolts fitted the wrong way round or washers left off causing the bolt to foul the subframe (there was a recall for this )

make sure the noise is not from the suspension compressor located nsf

the rack noise for loose bolts is normally associated with full lock

chassis ears are the key

[Han Solo]

Very strange, everytime I see a problem on here, the bloody same thing manifests itself on my car!!!

My osf suspension is now making a weird noise too. No rattle or grind, sounds like a rubber 'squeel' everytime I go over a speed hump. Is much louder when cold, and silent when wet! Suspension works fine so I'll have to get her look at, I reckon maybe a bush has failed or something.

My noisy right hand of the engine on startup is getting worse so I'll get that looked at also, I think A8 tech stated before something to do with the cct and runners....

and to top it all off, I have pneumonia at the moment, and when I checked my car yesterday I had a flat tyre and a dead battery (after 2 days!) so more cost.

It never rains, it pours!

[snapdragon]

Hello, did you sort this out?
Mine has this too now, the inner bushes of both top arms look past their best, but not terrible.
Looks like an air-strut-out job to do the rear upper arms.
Booked in on Tuesday for a look as I can't be doing all that in the winter.
May bite the bullet and get all 8 arms done.

[EG-4.0TDI]

Be interesting to hear how you get on with all 8 arms Snapdragon. From recollection to do the top arms (I once did them on an old A4 and the basic set up seems the same but it was a while ago so the exact details may be a bit wonky):

1) separate the lower rear (curved/banana) arm from the hub carrier to allow access to the bolt that secures the strut to the lower front arm (bolt is too long to come out otherwise)
2) undo the strut to lower front arm mounting bolt and release the strut from the lower front arm
3) release the upper arm ball joints from the top of the hub carrier
4) undo the three mounting bolts in the engine bay
5) lower out the entire strut and top mount assembly (which brings with it the top two arms)
6) replace the top two arms with the strut out
7) reverse 1-6 to refit.

Assuming it is, in broad terms, the same to above (air suspension might complicate things a bit) it would seem to me that the only labour difference between doing one top arm and all four arms for each side is a question of three additional bolts to be undone (and redone hopefully!) and the ball joint/hub carrier for the front arm.

Also worth bearing in mind is the re-alignment that will have to be done afterwards irrespective of how many arms have been done (probably between £100 and £200 depending on who does it).

Bottom line seems a no brainer to have both top arms done whilst you're in there. And, depending on your appetite for making savings but bringing forward future bills, if there's any danger of there being limited life left in the bottom ones, seems sensible to do those too.

From personal experience on my A8, also watch out for seized inner/outer track rod ends when doing the alignment afterwards as that gets quite expensive (as in another £800) as, again, you're into a situation where you might as well do all four ends to take advantage of the labour and alignment being done (and there's an additional set up to do with kick back on top of the alignment if the track rod ends are done). This can be a bit of a slapping as you think you're in for a few hundred for arms and then another whopper lands with the 'bad news I'm afraid sir'!

[snapdragon]

Thanks for the information. I have read the Audi dealer instructions for the top arms and they require removal of the air damper.
However, via google, I read on some other forum, maybe USA, that the only reason they move the air damper is only to get the angle of the arm correct for tightening the bolts on the inner bushes. The arms are fastened to the air damper off the car and the angle set by way of a tool and then the bolts torqued.
I would be happy for the air suspension to be set to Normal and the bolts tightened if the above would be a lot more labour (an risk of damaging boots etc..)

I did the brake pads today and looked at the bushes again, the rear one is torn on the nearside, so new ones should be a big improvement.

I'll report back on Wednesday.

[snapdragon]

Just to report that most of the noise was from anti-rollbar links, I changed them myself. They were FEBI ones of ebay for £45 and easy to fit.
I had my garage do the 4 top arms, it was £550ish as the pinch bolt was so badly seized on one side, they had to get a specialist in to drill it out with a pillar drill.
Front feels much tighter and refined now.

[snapdragon]

Be interesting to hear how you get on with all 8 arms Snapdragon.

Hello EG, yes, I did get all 8 arms done nearly two years ago, and the garage was able to just undo the top strut mount bolts and lower it without removing.
The parts were from GSF, not sure what make, after aa year a slight noise could be detected when turning left and the offside wheel hits a bump.
Now, at 22 months old, the front upper arms are shot (others look as sound as a pound), the balljoint is loose and the bush is torn, so I have bought two new Federal Moghul MOOG parts from Mister Auto and hope to do them this weakend. Mister Auto were half the price of Eurocarparts for Lemforder, and have a vast range of arm brands available at different prices, including, Moog, Febi, Lemforder, TRW and Delphi. They took a week to come from france via UPS, but it all went smoothly.