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Winter Driving

plherbert

New member
i just wanted to canvas opinion on the difference in grip/handling of a 997.2 C4S now that the winter months are here. I bought my car in February and obviously initially took it steady, but having driven circa 5000 miles in her now and attended a number of PEC driving days have gained a fair bit of confidence in my car during the summer months. Now I know the summer/winter tyre advice, but lately I've realised that pushing the car in damp conditions presents a very different level of grip.

I drove the other morning, temp was 7c and the roads were damp, not raining and seriously felt a noticeable reduction in turn in ability, clear understeer and felt like my confidence in the car was being eroded slightly. Now I do enjoy the analogue nature of the car and love feeling the connection and challenge of adapting my style, ultimately making me a better driver, but it did get me thinking about the variations between dry and damp/wet conditions. Clearly I have a 4s and at the time I got this slide I had sport mode engaged which I know will allow a bit more scope for drift, but I was thinking for the uninitiated how this could catch some people out! Especially if it was a 2s!

I've had the car back to the OPC for a road test and afterwards advised me that she drove beautifully. They tweaked the tyre pressures for me slightly but beyond that, they said all as expected, hence my post.

I'm just keen to hear your thoughts, advice, tips from all you 911 veterans out there. Maybe im just pushing a bit too hard at times, but hey, I'm sure on occassion we all do.

Many thanks

Paul.
 
Check your tyre pressures. I had to put 4psi in mine this past weekend as the cold weather takes hold. My car was still like sh*t to a blanket on a spirited drive on sunday.
 
The OPC did check them and added air probably just over 2 weeks ago, how often do they typically need checking, topping up. I've just bought a gauge to keep an eye on them and noticed quite a variation when tyres are cold/warm and also the obvious ambient temperature differences. I've got the 19" turbo wheels, do you have any datum pressures you like to aim for! I realise they are printed on the doors but again any tips for best practice.
 
Summer tyres perform significantly worse as it gets colder, add to that damp conditions and I think the OPC are right. I've been caught out several
times in those conditions.

To minimise this, make sure the tyres are warm, don't accelerate suddenly (especially with significant lock on) and take it easy. Otherwise get winter tyres fitted - but it's not really cold enough to use them.
 
plherbert said:
The OPC did check them and added air probably just over 2 weeks ago, how often do they typically need checking, topping up. I've just bought a gauge to keep an eye on them and noticed quite a variation when tyres are cold/warm and also the obvious ambient temperature differences. I've got the 19" turbo wheels, do you have any datum pressures you like to aim for! I realise they are printed on the doors but again any tips for best practice.



i have 19" turbo wheels on a turbo so I think. One are a bit wider than yours. I may be wrong.

I run 34psi front and 40psi rear on Bridgestones. Different tyres will also need different pressures IMO. Michelin have softer sidewalls so need more air. Bridgestone has harder sidewalks and can run a psi or two lower than Michelin. I am not an expert, this is all 'feel' for me so don't bank on my inputs :)

i always baseline my pressures at cold. Summer to winter is 4psi, easily. I last checked about 6 weeks ago.
 
plherbert said:
i just wanted to canvas opinion on the difference in grip/handling of a 997.2 C4S now that the winter months are here. I bought my car in February and obviously initially took it steady, but having driven circa 5000 miles in her now and attended a number of PEC driving days have gained a fair bit of confidence in my car during the summer months. Now I know the summer/winter tyre advice, but lately I've realised that pushing the car in damp conditions presents a very different level of grip.

I drove the other morning, temp was 7c and the roads were damp, not raining and seriously felt a noticeable reduction in turn in ability, clear understeer and felt like my confidence in the car was being eroded slightly. Now I do enjoy the analogue nature of the car and love feeling the connection and challenge of adapting my style, ultimately making me a better driver, but it did get me thinking about the variations between dry and damp/wet conditions. Clearly I have a 4s and at the time I got this slide I had sport mode engaged which I know will allow a bit more scope for drift, but I was thinking for the uninitiated how this could catch some people out! Especially if it was a 2s!
I've had the car back to the OPC for a road test and afterwards advised me that she drove beautifully. They tweaked the tyre pressures for me slightly but beyond that, they said all as expected, hence my post.
I'm just keen to hear your thoughts, advice, tips from all you 911 veterans out there. Maybe im just pushing a bit too hard at times, but hey, I'm sure on occassion we all do.
Many thanks
Paul.



Yes it's to be expected at this time of year, sometimes it's a "one off" patch which can frighten you like Diesel on a roundabout etc..

Although you've got more rear grip that front (Hence Understeer) especially when on damp roads,

Your contact patches are also wide (Left to right) and not long (Front to Rear) great for Summer but not so much for winter where
a Family hatch Focus for example on 15" Wheels and 195/60 series tyres.. will corner better!

Check out what Michelin says about winter conditions and their braking example between Summer & Winter Tyres on snow is
quite a substantial (Scary) statistic

http://www.michelin.co.uk...ter-weather-guide.html

R


 
The C4 inherently understeers, pushing more from the rear than pulling from the front. The additional weight of the AWD system amplifies this characteristic.
Increased drive to the front only happens when the rear wheels are close to breaking traction. So it either needs to be very slippery or you are giving it plenty of stick and getting the back end sliding, in order to benefit from front wheel drive.

I doubt you would notice the difference in grip of winter or summer tyres solely from a drop in temperature to 7C, but winter tyres will likely give better purchase on greasy surfaces.
Regards,

Clive

 
Some good knowledge out there, Clive is that to suggest unless you have the car sideways the C2 would handle better? Seems quite counter intuitive, would be great if you could tweak the system.

I have PASM, which I believe includes a limited slip diff, should I have this turned on to improve grip even though if feels a very stiff ride on the U.K. roads?
 
The C2 is better balanced. Find a quiet roundabout and drive both cars around it to confirm this.
The LSD improves rear traction and therefore tends to increase understeer, but improves acceleration out of slow bends.
Regards,

Clive
 
Lancerlot said:
The C4 inherently understeers, pushing more from the rear than pulling from the front. The additional weight of the AWD system amplifies this characteristic.
Increased drive to the front only happens when the rear wheels are close to breaking traction. So it either needs to be very slippery or you are giving it plenty of stick and getting the back end sliding, in order to benefit from front wheel drive.

I doubt you would notice the difference in grip of winter or summer tyres solely from a drop in temperature to 7C, but winter tyres will likely give better purchase on greasy surfaces.
Regards,
Clive




All Production cars are balanced for understeer, it's a far earlier (Safer) signal felt from the steering wheel and not the hips like
(Oversteer!)

The additional weight of the front transmisssion is a benefit compared to lighter earlier (2WD) 911's as the weight compresses the tyre further to the tarmac for more mechanical grip.

However a lot of 4 wheel drive cars understeer more than RWD & FWD and it differs depending on the split or in this case the feature and capability for the electronics to change it. The old Skool Audi's were notorius for Understeer even early TT's and Impreza'a etc..I'd say Porsche's systems are the best out there I've driven even the 4WD car's without variable bias.

For sure you can have all the most advanced electronics in the world which are working in milliseconds without you knowing about
it, but if the good old fashioned Rubber tyre molecules lose friction due to adverse conditions you still going to slide somewhat regardless!

There's no question (If you've not tried and experienced them?) that Winter tyres are a Huge difference in feel and grip compared to a regular Summer tyre, each tread block usually has lots zig zag "sipes" cut in them, the sidewall is softer, the rubber compound more able to move and it provide friction much quicker in colder conditions.

For those that have sometimes experienced how harsh your car can feel when you first drive it (having been layed up for a few weeks or months) when the suspension feels hard crashy and the tyres are cold etc...The winter tyres feel "on it" straight away.


Often when some people have 2 sets and swap for each season when taking off either set the differences in ride and feel can be quite dramatic, and in a situation of wet - greasy - cold and damp roads a Winter tyre is in my opinion (And others than have experienced them) the difference between driving home or sitting in a tow truck with your car on the back!

R






 
Didn't want to interrupt this thread while serious discussion was in full flow, but winter seems to have arrived up here. We took a run to Glenshee Ski centre last Friday to find the first snow of the winter - we were not disappointed! Could this be what's in store this winter? More photos on the website www.barlow.org.uk
dsc04329-for-web-1100_orig.jpg


 
The colour of the new motor makes a splendid contrast against the white stuff, Paul and full marks for being brave enough to take it out on those roads. You're really hardy annuals up north! [:D]
Regards,
Clive
 

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