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Strange Noise/Sensation upon Steering Full Lock

Snowball171

Snowball171

PCGB Member
Member
Hi All,

bit of a weird one - but may be normal as I've not had the car long. When I pull the car over to full lock on the steering when coming out of a gap it feels almost as iff the wheels a slipping and rubbing on something. The logical side says its because its running 19" wheels with really low profile tyres that when it gets pulled over hard its camber changes - but then again it could be disaster waiting to happen! Only does it when it's all the way over on either direction, no whinning or complaining from the car itself just weird sensation. Normal driving track and drives fine.

Any opinions or theories welcome

Thanks in advance[:)]
 
I had this problem on my 981 [19"]and on my AMG Mercedes [20"] used every day
It only happened in cold weather, once the tyres were nice and warm the problem went away/reduced
On the AMG I had the tyres inflated with nitrogen and this reduces the problem and has the added benefit that you get very little pressure variation regardless of the ambient temperature
So, I suggest you get the tyres really warm and see if the problem goes away/reduces
Peter
 
A perennial complaint on the forums at this time of the year Philip as temperatures head downwards.

You most probably notice it more when reversing on full lock when the tyres are cold. It's just the tyres skipping over the road surface, causing a juddering effect - wide, low profile tyres (with very stiff sidewalls) and conflicting steering angles are the cause.

Quite normal and nothing to worry about; and some tyre makes appear to be more prone to it than others.

Jeff
 
It's the Ackermann effect and well written about on different forums. It is more pronounced in cold weather, I have Pirelli P zero tyres which seem particularly bad. Don't worry as the comments above say it's perfectly normal.
 
The radius (and therefore circumference) of the turning circle will be shorter on one side of the tyre compared to the other. The wider the tyre, the greater the difference. Also, the deeper the tread, the more flex on the tyre blocks, so conversely, a more worn tread is more likely to skip, rather than flex. This is why people say their old tyres were rubbish and changing them (usually to another brand) "solved" the problem.

As people have said, this is the Ackerman effect and nothing to worry about.
 
That's right Bryan. Ackermann steering geometry dates back to the days of horse-drawn carriages when wheels (and tyres) were very narrow, and I very much doubt that you'll find a modern car with pure Ackermann geometry. Wide, low-profile tyres and complex suspension dynamic and compliance effects mean that a modified Ackermann geometry is employed.

Jeff
 
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