Wayward handling when going straight.

[RoyC]

11 hours ago, Stevey Y said:

Thats the one, BUT its caused by the appalling state of our roads especially the M25 concrete sections which five years after its commission by Lady Thatcher started to break up AKA concrete cancer where the individual sections start to move away from each other which is why they are so keen to resurface the whole thing, if you take in to consideration that most heavy luxury cars run wishbone suspension with a 30 degree coilover shock absorber mounted to maintain dead centre pressure on the middle of oversize width tyre to stop this behaviour its no wonder that cars such as Audis fitted with any width tyre 235 + will drag due to the tyre foot print being so wide 225 is about as good as it gets with our roads, I think the generalisation that this applies to all VAG vehicles is a bit silly as most of the lower ranges use different width tyres which rarely exceed  a 215 width and won't ever encounter this problem as I explained before when I had a conversation with my neighbour an ex powertrain engineer at Wolfsburg he explained that people think bigger is better so thats what they sell them regardless of the fact that large wheels say 19 inch and low profile tyres are 40% heavier as the rims are reinforced due to the lower tyre profile therefore they are more prone to aquaplane and tramline on deviant surfaces so its not the set up thats wrong its the road surfaces, they are a large contributing factor, if you watch the old rally footage of when the quattros first started you will notice they ran skinny tyres say 195x60 x15 for example as this cut out 75% of steering drag over very rough terrain, if I drive with four passengers and a full boot up to Gatwick on the tarmac sections I only need to make minor adjustments to the steering if I go round to Heathrow from there its like playing chase the ace on the concrete plus you have the infernal clicking from the road except where they have ground about half a mile as an experiment the clicking ceases as does the wandering, I came down from 19inch wheels with 40 profile tyres to 17inch wheels with 55 profile tyres which gave a better ride and no compromise with the handling as well as about 6 miles more to the gallon I always used 101 XL tyres and never had a problem in 240,000 miles and with 200 HP and 420nm of torque it was no shrinking violet, final analysis is if you want this type of thing to calm down go down to 17 inch wheels and a slightly narrower tyre, if not you will have to live with it for the looks, my car does it on 225x55x17 so god knows how much extra noise/dragging you would get with a wider aspect tyre and 19 inch rims.

Steve.

You can't say that of all cars.

I have 255 35 19 and have never had any wandering in 13 years.

[Stagn8]

Thanks for a this information Steve, it is reassuring to have a bit of background on why it happens, I was finding it a bit stressful not understanding the root cause.

For others not experiencing it, it is only under particular circumstances, very poor  surface and heavy loading. Unless you replicate the situations Steve and I describe then hopefully you won't ever get it.

[Stevey Y]

11 hours ago, RoyC said:

You can't say that of all cars.

I have 255 35 19 and have never had any wandering in 13 years.

Hi when was the last time you drove on the M25/M1 at speeds off 70mph, and at no point did I say that it was all cars I explained that different steering set ups behave in a different way on that type of surface also explaining that the Audi set up being finely tuned was susceptible to this type of problem on sub standard surfaces, this opinion is based on thousands of miles of travel on a lot of different roads the aforementioned roads being the worst, as for claiming all VAG vehicles are the same, never said that either, that ranks along side with the old saying for pubs, are you calling my pint a tart, I am glad Keith grasped the point of what I was saying before he rushed off to buy new suspension, tyres, tracking, its a problem with the surface, NOT THE CAR.

Steve.

[RoyC]

8 minutes ago, Stevey Y said:

Hi when was the last time you drove on the M25/M1 at speeds off 70mph, and at no point did I say that it was all cars I explained that different steering set ups behave in a different way on that type of surface also explaining that the Audi set up being finely tuned was susceptible to this type of problem on sub standard surfaces, this opinion is based on thousands of miles of travel on a lot of different roads the aforementioned roads being the worst, as for claiming all VAG vehicles are the same, never said that either, that ranks along side with the old saying for pubs, are you calling my pint a tart, I am glad Keith grasped the point of what I was saying before he rushed off to buy new suspension, tyres, tracking, its a problem with the surface, NOT THE CAR.

Steve.

Point taken Steve.

[jdragon]

There has been some great collaboration and shared experiences here.

It does appear this could be the result of loading and road conditions, however if the car was mine I'd still have it checked.

[Magnet]

I’m still biased towards loading and appropriate tyre pressures as being the principal contributors, with road conditions as the aggravator. 

[Stevey Y]

13 hours ago, Magnet said:

I’m still biased towards loading and appropriate tyre pressures as being the principal contributors, with road conditions as the aggravator. 

I would like to point out that its two different models with two different size wheels and definitely different brands of tyres that are experiencing the same sort of problem, because my tyre pressures are checked every ten days by my local tyre supplier who's inflation devices are calibrated every month I have total faith in their accuracy, this is rubber stamped by the amount of miles I get out of my mid range tyres, so far 26k rears and 8k fronts half worn which on a cab is legendary, on Vinces advice I have always run the pressures at two pounds over pressure cold 38 pounds rather than 36 as this equates to an expansion rate of 42 pounds for motorway/loaded work but has the added benefit of not allowing the edges to wear prematurely because of wall roll due to frequent cornering, this advice comes from a tyre shop where the owner has over forty years of experience, [Hands On] and has a vast experience of many tyre brands and will tell you whats good and whats not even to the point of recommending a cheaper tyre over a top end tyre because I would get better milage for my type of work, thats why he has had my business for twenty years, I am in no doubt that many other Audi owners will have had the same problem and never noticed, most people who use these vehicles don't know a lot about steering etc, its just a lovely form of transport and the only time they ever get really alarmed is when something goes badly wrong, you said it yourself the car tries to tell you something, most ordinary owners only notice when whatever it is fails, I wish I had the time to have a schematic drawing of the boot and weigh each suitcase to place them in the precise location for optimum load level but I just use the old formulae heaviest/biggest over the rear axle and cabin luggage at the tailgate end, loading and tyre pressures have already been worked out before the car is sold to the public as have the wheel cambers and steering/suspension bush deformation rates under Max/Minimum loadings, which only leads to one conclusion its the road surface, same loading on tarmac does not produce the same results as ancient crumbling concrete.

Steve.

[jdragon]

On 8/23/2022 at 8:19 AM, jdragon said:

I'll be on the M25 in a couple of weeks, and will report back.

So I did the drive. Car was loaded with me and three others at around 420kg combined mass, plus short stay luggage in the boot. No handling issues to report 🙂

[jdragon]

On 8/25/2022 at 8:48 PM, Stevey Y said:

I would like to point out that its two different models with two different size wheels and definitely different brands of tyres that are experiencing the same sort of problem, because my tyre pressures are checked every ten days by my local tyre supplier who's inflation devices are calibrated every month I have total faith in their accuracy, this is rubber stamped by the amount of miles I get out of my mid range tyres, so far 26k rears and 8k fronts half worn which on a cab is legendary, on Vinces advice I have always run the pressures at two pounds over pressure cold 38 pounds rather than 36 as this equates to an expansion rate of 42 pounds for motorway/loaded work but has the added benefit of not allowing the edges to wear prematurely because of wall roll due to frequent cornering, this advice comes from a tyre shop where the owner has over forty years of experience, [Hands On] and has a vast experience of many tyre brands and will tell you whats good and whats not even to the point of recommending a cheaper tyre over a top end tyre because I would get better milage for my type of work, thats why he has had my business for twenty years, I am in no doubt that many other Audi owners will have had the same problem and never noticed, most people who use these vehicles don't know a lot about steering etc, its just a lovely form of transport and the only time they ever get really alarmed is when something goes badly wrong, you said it yourself the car tries to tell you something, most ordinary owners only notice when whatever it is fails, I wish I had the time to have a schematic drawing of the boot and weigh each suitcase to place them in the precise location for optimum load level but I just use the old formulae heaviest/biggest over the rear axle and cabin luggage at the tailgate end, loading and tyre pressures have already been worked out before the car is sold to the public as have the wheel cambers and steering/suspension bush deformation rates under Max/Minimum loadings, which only leads to one conclusion its the road surface, same loading on tarmac does not produce the same results as ancient crumbling concrete.

Steve.

Your approach to loading and safety is worth recognising. You'd get on very well with the guys from the company who manage our airport runs. 

[Stagn8]

Coincidently, have just towed the van down to Blandford Forum. which for me is M3. A303, A354 and the car behaved impeccably, it was quiet relaxing! Not a hint of waywardness, so, for me it does confirm that road surface is the problem.

Thanks for all the comments, it has been interesting, particularly the comments from Stevey Y.

Cheers all.