front tyre scrub

[Paulo cuttino]

Can someone tell me if front wheels making disconcerting chattering noise when on lock is normal, I’ve owned my 981Cayman S for a month now, have not spoken to dealer about it yet, don’t want a biased answer coming from them ( maybe).

[Bushman]

Hi Paulo. Its most likely the tyres, this is a subject that a few of us have experienced too. I believe it is down to the tread blocks flexing then popping back when on full lock on a low profile tyre that is designed to resist torsional loadings. Normally only noticeable when on full lock, then you can feel it through the steering.  I get it on mine but only at really slow manoeuvring speeds on cold tyres. 

hope this helps.

[Mk1]

My 981 CS also had this tyre `chatter / scrub` ... when on Pirelli PZero N0 tyres.

 

When I changed them for Michelin Pilot Sport 4S N0 and reset the geometry settings the `chatter / scrub` was `no more`. Maybe it was down to the `freshness` of the new rubber and / or the revised geometry ?

 

Now, after 9,000 miles the `chatter / scrub` has returned, albeit not as bad as before. The tyre wear is even but I will be having the geometry checked next month.

 

pp Bushman`s comment and from reading other reports I understand that this `effect` is to be expected given our vehicle`s design.

[briggy]

I'm sure I've already replied to this, but my post seems to have gone. Anyway....

 

When you turn a corner, the inside of the tyre is travelling a different radius to the outside. Say you're turning left, the inside of the right hand wheel has less distance to travel that the outside of the wheel. As the width of the tyre is fixed, something has to give. The noise you hear and the effect you feel is (in the example above) the inner edge of the tyre skipping along to keep up with the outside edge of the tyre. The wider the tyre and the tighter the turn, the greater the effect. I think it's called the Ackermann effect.

 

I would imagine that newer tyres have more flex and the blocks can stretch or compress, minimising the effect.

 

Cheers,

Bryan

Edited February 1, 2019 by briggy