wobbly A4 cab!

[eqvvs63]

Hi I wonder if anyone can please help, I'm new to the world of Audi and have bought a 05 plate A4 S-line Cabriolet in dolphin grey which has started vibrating through the steering wheel and pedals when on slightly rough road surfaces and becomes un-bearable on bad surfaces. I thought i'd solved it when I realised that I'd jet washed the weights off the alloys, so off i went to the garage but still getting the same vibration the only other notable thing is that i have pumped up the tyres around the same time as the jet washing incident as when I bought it they were at around 33 psi so I took them to 38 psi, could it be a tyre fault?

Any help with this would be greatly appreciated as it is wrecking my Audi experience

 

[rowdyboy]

Is 38 psi correct for your model?

 

[eqvvs63]

It says 41 i tried that first but was getting the same problem so tried dropping it down a little to see if it made it more comfortable but unfortunately not

 

[rowdyboy]

Sounds as though you have play somewhere, try jacking it up and feeling for any movement.

 

[old-man]

My 08 S-Line cab on 235/40/18 says 33psi all round, well thats what the door sticker says. Do they differ by model year?

 

[eqvvs63]

I'm not sure if they differ, mine has the same size tyres the door sticker says 38 or 41, i really need to double check it though surely thay can't be that different.

Don't think there's a major problem movement wise as it went in for service(non audi) and I mentioned it so they checked the suspension, joints and the like and said it was all fine which makes me think tyres

 

[eqvvs63]

Just checked it defo says for 235/40/18 38 psi next to the picture with 2 people and 41psi for the one with 4 people, sounds odd though if your 08 reg says different!?

 

[old-man]

Just been out to check mine (2.0TDi 140BHP) and it say.

33psi for 2 people, upto 100mph
36psi for 2 people, over 100mph
42psi for 4 people

 

[eqvvs63]

Ok thanks, I think I'll be taking a trip the the garage to drop them to 33psi to see if it makes it better, I'll keep you posted

 

[rowdyboy]

It depends on which engine size aswell. My pressures are 42psi all round, going up to 46 when it's fully loaded.

 

[jdp1962]

It also depends on the accuracy of the pressure gauge on the airline you're using.

 

[eqvvs63]

Its a 2.4 petrol, I'm hoping its as simple as dropping them down 5psi otherwise I'm baffled with the garage saying that the suspension/bearings/shockers are all ok

 

[eqvvs63]

Ok depressed the tyres to 33psi and its made it slightly, very slightly better but i can still feel vibration through the pedals on anything but very smooth road surfaces anyone got any more suggestions? otherwise this is going to be the shortest time I've owned a car at 6 weeks :O(

 

[rowdyboy]

The thing is, it's very hard to replicate the loads put on the suspension parts by hand. Even the slightest wear felt by hand is multiplied when it's loaded up. Have you spun the wheels and listened/felt the bearings for any noise or grinding?
I take it you got your tracking and 4 wheel alignment checked?
If you suspect it's a wheel or tyre, why not try sticking your spare on, one side at a time and see if it makes a difference.

 

[eqvvs63]

I got the garage to check all the joints, bearings, suspension when it was serviced 2 weeks ago they said everything was ok and i needed to look into the tyres/balancing so that's what I'm trying. Its due some new tyres on the back so i think I'll take it in and have the new ones on the front and move the current fronts to the back see if that solves it

 

[eqvvs63]

Ok I'm back the problem seemed to subside over the last few weeks but now its back :O( The only significant thing I could think of is I have filled the car up with fuel and its been horrible since, could it be weight related? I have no idea what components of the car that would affect that would cause this annoying vibration, please help :O(

 

[Newtome]

I've got exactly the same problem with my 1.8T Sport. Indy checked and said found nothing. Had new front tyres, all re-balanced, 4 wheel laser alignment. 2nd indy suggested front lower rear arms were worn, so replaced those. Problem still there. From what I've read, it could be a anything from wear in shocks (not leaking and 'feel' okay so wouldn't be easily spotted on inspecion) to an imbalance in the propshaft or even a bent wheel, although I would hope this would be spotted when balanced. Adds up to an exensive process of elimination, from what I can make out.

I feel like you - it's wrecked my enjoyment of the car and is really denting my love of Audis. Spent all my hard earned buying it, so can't afford to chuck hundreds at it.