Front suspension knock....

[randall977]

Just investigating a couple of large knocks I get when steering hard right - the car actually feels like it's jumping sideways as well! I would stay it knocks / jumps once per wheel revolution on hard lock (obviously just an estimate). It is an 05 A4 Cabrio quattro 1.8T - the CV boot is fine (no splits)... It also sometimes feels like there are a couple of small knocks as you pull off in first...

[alanK]

hi randall,

I have EXACTLY the same problem on a 04 A4 cabrio 2.4 multitronic.

have had the car 6 months and 'noticed' it after a few weeks of purchase.

it has got steadily worse - part due i would say to the fact that the front left tyre is now worn massively more than the front left (or rears)

brought it to the nearest VW/Audi service centre because a knock had developed in the front left.

results:
front left CV changed - knock has disappeared nearly completely except under medium/hard breaking while turning.

SHUDDER REMAINED
brought it back & they had it for a few days.

Results:
they said - rechecked alignment and tracking (i presume camber and caster but dont know). problem remained

after consulting with Audi HQ they lifted the car and loosened the sub-frame as "it can sometimes get out of line". it was "but very little"

problem still remains.

had it to my mate for the last week. hes the guy who does the local NCT (MOT) tests here (so knows what hes looking at)

siad it looked perfect underneath and he wouldnt worry - didnt manage to recreate problem while in car with him.

he recommended "computerised" tracking and camber and caster - not laser type. i dont know if this has already been tried but i think the VW guys must have before tackling the sub frame

stumped aand it pi**ing me off.

have you had any results? V interested

Alan

[alanK]

oh yeah - IT IS "jumping" as you say.
get a mate to stand outside while you recreate the problem for him

have read other posts about worn tyres, "sports" tyres and such but i have a feeling there is much bigger fault at work here.

[randall977]

My conclusion is that it is nothing to do with the CV - there is no evidence to suggest it is. I have been told that it is to do with the width of the tyres and the suspension causing scrubbing (sideways movement of the tyres while turning hard lock). Possibly partly due to partial wear of the tyres effecting the geometry. Funny that it only tends to do it when turning right??? So I've decided to forget about it as it's nothing which has worn or needs fixing. It may well be a design error, tut tut Audi!

It's a cop out I know but sometimes it better just to live with things!

[alanK]

i agree with you about the CV. but my problem did result in having to change the front left CV - which as i mentioned did get rid of the knocking.

so i would feel that this problem caused undue wear on the CV. also as i said my front left tyre is buggered now, while the front right is fine.

i think the underlying problem is causing all these (costly) "symptoms"

other things noticed which i presume are one in the same:
reversing out of drive (right hand down) over a little kerb bump produces a large jump

car seems to follow ruts in the road much more than should be normal (this may be a toe problem)

the car just doesnt seem to handle correctly since i got it back from VW - to the point that i drive it very carefully.

[randall977]

That doesn't sound good - what happens when you drive along a straight road and let go of the steering wheel? You may have mentioned this but are the tyres in good condition, correctly inflated matched in pairs? I assume the history of your car is good? One of Audi's strengths are their sure footed handling. You need to find someone who can give you a second opinion - I usally use my dad!

[alanK]

the car tracks fine in a straight line - no pull.
all the tyres (except front left) are in good nick - matched set of 4.
havent checked tyre pressure recently.

as an update i rang the VW crew i brought it to. service guy assured me that they use computerised tracking and that camber and caster were checked - although he said he couldnt furnish a copy of the print out.

will check the pressure tomorrow and give you an update.

Al

[alanK]

me again,

well i had forgotten all the nuances about this problem as its going on so long, and my cabrio is off the road because of it.

contrary to my last mail the car tracks like a drunken mule when i let go of the steering. there is no pull on the steering but after a few seconds it will wander left or right, pretty drastically.

this only developed after i got it back from VW/Audi service.
the guys there said at the time "you know the problem you were having with the front right, well we have it happening on both sides now" this was after the sub-frame loosen/re-tighten.

input really appreciated randall. you seem to know a bit about cars and your the only man i have found with the same issues as myself. so maybe i can help you out in the long run.
Al

[alanK]

sorry mate
"you know the problem you were having with the front right"

should have read "you know the problem you were having with the front left"

[randall977]

Apart from the knock on hard lock when coming out of the garage my car is fine. So the problem effects both sides on your car; so the fault is a component common to both sides... What about the power steering? Steering column play? Is there a sensor which helps the car track straight by default (as in when you let go of the steering on a straight road)? With electronic PAS a senors helps the car to go straight but I think Audi's are traditional hydraulic. I assume all your suspension rubber bushes have been checked for wear / play? Have you tried swapping the front and rear wheels over in case there is something funny going on with the tyres / alloys themselves? Shock absorbers? - look for any sign of wetness around the top...

Check out this tread for clues as well;

http://www.vwaudiforum.co.uk/forum/showthread.php?t=57326&highlight=steering