Ackerman Effect?

[Tricky54]

I was introduced to the Ackerman Effect on my first Porsche, a 2003MY 986 Boxster S, when I reversed off my driveway on fairly high steering lock. This was on Michelin PS2 tyres. It never occurred at other times.

I have recently acquired a 2014MY 981 Boxster GTS and had a 4-wheel steering geometry check carried out, and minor front tracking adjustments was all that was required. Everything was all nicely within the factory specifications.

However, from day 1 of ownership, the car has produced alarming judders from the front tyres on moderate lock going in reverse, but also going forwards. It feels like the tyres are being dragged sideways across the tread, and the sound is very noticeable, even by my passenger. The tyres are Pirelli P-Zero.

Does the above sound like the Ackerman Effect or is there something I should check over? It is markedly more noticeable than my old 986 S!

 

[PeterJRolt]

The wider the wheels and lower the profile, the more noticeable the effect.

Try not to use full lock if it disturbs you.

 

[Motorhead]

For reference see my post #7 from earlier this year.

Tyre Skip

Hi all, could anyone recommend the best tyre to minimise the dreaded cold tyre skip. We are on 20inch wheels. Currently on Pirelli but have been told that Continental or Michelin are a better option ? Thanks, Tony.

www.porscheclubgb.com

Jeff

 

[Tricky54]

For reference see my post #7 from earlier this year.

Tyre Skip

Hi all, could anyone recommend the best tyre to minimise the dreaded cold tyre skip. We are on 20inch wheels. Currently on Pirelli but have been told that Continental or Michelin are a better option ? Thanks, Tony.

www.porscheclubgb.com

Jeff

Thanks Jeff. That was most reassuring. I was quite perturbed at how much worse it is on this car compared with the old 986!

 

[Motorhead]

The fact that probably you’ve gone from 17” wheels on your 986 to maybe 20” wheels on your 981 and wider, lower profile tyres will have made a significant difference.

Different manufacturers’ tyre compounds could make a difference, but unfortunately it’s something we Porsche drivers have to live with during the colder weather.

I wish I had a £ for every time I’ve responded to posts on this topic over the years!

Jeff

 

[Wollemi]

The cold weather does make the tyre skip at very low speeds a lot worse. Worn tyres are worse than fresh tyres - presumably due to depth of tread blocks. There isn't really any difference between brands - people sometimes think there is because they change to new tyres and they are better - because they are new.
Winter tyres will eliminate the issue entirely.
Perhaps you should just regard the tyre skip as a warning that your tyres are being used in sub-optimal conditions.

 

[MrDemon]

Pirelli P-Zero lol nothing more to add, the worst tyre made for Porkers ever.

"quote" There isn't really any difference between brands ! there is a massive difference the PS4S sidewall is more compliant and progressive.




imo just bin the P=zero's they are a shocking poor tyre, and fit PS4S's a shockingly amazing tyre.