991 full lock dragging / crabbing issue

[mrporsche]

Afternoon,

the car is a 2013 4s, 245/35/20 tyres.

When pulling out of the drive, you require a full lock tight turn to get onto the road, it doesn't like it.

It seems to shudder as if it is being dragged round, "normal" steering inputs dont have any issue.

Tyres dont appear worn.
Is this the front diff working hard and not liking it.
Tracking
something more serious ??

I do get it on a rear wheel drive sometimes, so perhaps wider tyres don't like tight turns ?

Thanks

[brman]

I thought most performance cars had anti-ackerman so this would be normal? I would wait for someone who knows the 991 to comment though.

[interstellar]

It’s normal.

Google Ackerman effect. Wide tyres and porsches are known for it.

[av185]

Perfectly normal for all 991s.

[timberman]

yes perfectly normal,

I found it improved no end when I changed over to PS4S's,

the P zero's were really bad,

it's also a lot worse when the tyres are cold, i.e in winter

[Cheib]

It is not the Ackerman effect...read threads like this every year at this time of year It’s because Porsche N rated tyres have compounds which go hard in low temperatures....the tyres 99% of Porsche’s are supplied with in this country are summer tyres. We have a Cayenne and a Macan as well as a 911 and a Boxster. They all do it at this time of year but the Cayenne and Macan stop doing it when I put the winter wheels and tyres on them.

If you want to get rid of it you need to put some more suitable tyres on for cold weather. Although it is a good reminder than your car won’t have the grip levels it has in summer.

[Red 5]

Cheib said:

It is not the Ackerman effect...read threads like this every year at this time of year It’s because Porsche N rated tyres have compounds which go hard in low temperatures....the tyres 99% of Porsche’s are supplied with in this country are summer tyres. We have a Cayenne and a Macan as well as a 911 and a Boxster. They all do it at this time of year but the Cayenne and Macan stop doing it when I put the winter wheels and tyres on them.

If you want to get rid of it you need to put some more suitable tyres on for cold weather. Although it is a good reminder than your car won’t have the grip levels it has in summer.

It does it just the same in warm weather when it’s rainy on low grip tarmac.

All summer tyres are less flexible at low temps. Porsche N rated tyres are no different in this regard.
We’d had a 991.2S, Cayman GTS x2 and a Macan Turbo and SD all did this on smooth wet tarmac in the summer too.

Full lock in car parks still creates the same effect, but it is worse in the winter when the rubber is less pliable.
You only have to look at a Porsche on full lock to realise why it’s happening. Steering geo is the reason and only the edge of the tyres are touching. This is why people refer to Ackerman.

The geo is designed to keep a flat contact patch on the loaded side of the car, as G builds in corners.
The downside of this, is loads of people calling dealers and asking the same question on the internet over and over.
The same geo minus the G load while manoeuvring is why.

As mentioned above, the PS4S is more flexible when point loaded in this way, where as the P-Zero is way more rigid.

[mrporsche]

Thank you for your replies.

Explains why i have it on a couple of cars.

[superlightr]

yes have had this on a few cars but having just gotten back into Pork and a 991.2 Targa with 4 wheel steer (first time on a car for me) - Ive not had this. I guess the all steer wheels reduce or eliminate the crabbing. Yah !

[Gixer968CS]

My 997 does it too

[LordGrover]

It's worse when it's cold. My 981 is terrible this time of year, but once it the weather's a little warmer it disappears.

[Gander101]

superlightr said:

yes have had this on a few cars but having just gotten back into Pork and a 991.2 Targa with 4 wheel steer (first time on a car for me) - Ive not had this. I guess the all steer wheels reduce or eliminate the crabbing. Yah !

Unfortunately FWS doesn’t mean it doesn’t happen, my Pork with FWS does it

[Centrente]

P Zeros are definitely the worst for this.

MPS4Ss much better but still happens a bit.

All season or winter tyres seem to eliminate it. (On the right cars)

[jay2000]

Really worrying the first time I experienced this on my C2S. Without these forums, I would be knocking on the door of the dealer demanding my money back. Its just that after 30 years of driving multitude of cars, only the porsche suffers from this. Maybe my previous cars are not sporty enough.

[dgswk]

My 992 C2S does it when 3-point turning at the end of our road. OPC said 'they all do that sir!'

[therams]

Yep my 991.1 and cayenne both do/did this

Normal apparently

[NBTBRV8]

It is exaggerated by P-Zeros, but it is the tyres. As they wear down the blocks get less less side to side movement so the tyre blocks starts to skid instead of flex/bend and the tyres get hard with age. When you fit new tyres again it will improve dramatically.

[Blakes003]

My 991.1 does this. I too made enquiries and told perfectly normal.

I have 20" P Zeros on my car.

[David W.]

Dab of throttle usually brings the back end round so you need less lock, simples.
Next?

[dgswk]

David W. said:

Dab of throttle usually brings the back end round so you need less lock, simples.
Next?

^ what this chap said, smooth surface, in the wet