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-   -   Snow driving weather (http://www.focusfanatics.com/forum/showthread.php?t=305791)

spiderpig 01-05-2013 11:27 AM

Snow driving weather
 
I just got my 2013 Ford Focus Titanium last month and have been loving it. Recently it's started snowing here in PA and I want to get some clarification about driving in the snow.

In my old 2004 Toyota Echo I had Drive, Second Gear, and Lower Gear. So when it snowing I would usually switch to lower to have the engine help me brake. But with my new car there is drive and sport. Would I need to put the car in Sport mode and just keep in lower gear myself, or would Sport mode give me more grip in snow?

Training my driving behaviors with the new car is a little challenging but lots of fun.

turbosleepa 01-05-2013 12:19 PM

In sport mode you can switch to a lower gear with the button on the shifter

zehkaiser 01-05-2013 12:32 PM

You should be careful using Sport (auto) mode while driving in the snow. I've found that if I shift down to S and touch the brakes, the car will down shift pretty aggressively to lower the speed. This could cause you to lose traction with your front wheels. Be sure to leave it in Drive, or use Sport (manual) and be smart about it.

spiderpig 01-05-2013 02:18 PM

So the best method is to go into sport and manually keep it in first or second gear?

zehkaiser 01-05-2013 02:38 PM

I wouldn't keep it in a low gear all the time. Try to keep your RPMs as low as possible while doing anything in a low traction situation. Let me try to explain a little bit that will hopefully shine some light on suggested driving during poor conditions.

The coefficient of friction on snow is usually between 0.3 - 0.6. This is much lower than the coefficient of friction on dry asphalt, which is usually about 0.9. Every action you take in a FWD car 'uses' some available friction from your front tires on the surface you're driving on. That means that if you're turning WHILE braking or accelerating, you have a greater chance of losing traction. Because you're in a FWD car, all force from the engine will also be on your turning wheels. Using the brakes instead of your engine will put ~70% of the stopping force on your front tires, and ~30% on your rears. Your hand brake will be 100% braking from the rear tires.

So to get back to driving on snow, if you're driving in 2nd gear at 25 mph on snow, you're probably around 3k rpms. If you try to make a turn and you let off the gas to do it, you're going to cause the engine to slow the front tires. This uses some of your 'available' friction. Begin turning, and it'll use more. Try to turn too hard, and you're gonna slip.

The best method for driving where traction is an issue is to reduce the overall forces on your tires. Don't turn sharply, don't accelerate/decelerate quickly, and take your time getting places. Oh, and look out for the idiots who will slide right out in front of you because they were going to fast.

Also, don't try to stop using the hand brake. It's much different from using the pedal, and you can easily lock up your rear wheels.

Joeywhat 01-05-2013 02:39 PM

No, the best method is to use your head and keep it in an appropriate gear. If you're not sure what an appropriate gear is, leave it in drive, it'll do just fine.

dan50 01-05-2013 03:33 PM

Don't use engine braking at all in the snow. If traction is compromised I'm not sure the ABS system will intervene. Plus if you use the brakes too hard you can back off in an instant; not so with a downshift. Best just to leave the car in "D" when it's snowing, in my opinion at least.

spiderpig 01-05-2013 06:12 PM

Thanks for the all the explanations - it's really appreciated. I'm not a "car" guy by any means. I'm an IT guy so I can tell you about all the systems and how they work, but car stuff is an enigma to me.

Going from my old car to my new I'm finding I have to retrain some of my driving habits. Like in snow I always put the car in lower gear on hills before. Also, my older car didn't have ABS so that's something new I have to get used to.

Follow up question with this...reading about the activetrac w/ESC it seems like if a wheel loses traction the system will brake on the other side to try to maintain control. Do you guys find this is helpful in snow conditions? It almost feels like where giving away some control to a computer.

dodgeguy 01-05-2013 08:18 PM

Quote:

Originally Posted by zehkaiser (Post 4526719)
I wouldn't keep it in a low gear all the time. Try to keep your RPMs as low as possible while doing anything in a low traction situation. Let me try to explain a little bit that will hopefully shine some light on suggested driving during poor conditions.

The coefficient of friction on snow is usually between 0.3 - 0.6. This is much lower than the coefficient of friction on dry asphalt, which is usually about 0.9. Every action you take in a FWD car 'uses' some available friction from your front tires on the surface you're driving on. That means that if you're turning WHILE braking or accelerating, you have a greater chance of losing traction. Because you're in a FWD car, all force from the engine will also be on your turning wheels. Using the brakes instead of your engine will put ~70% of the stopping force on your front tires, and ~30% on your rears. Your hand brake will be 100% braking from the rear tires.

So to get back to driving on snow, if you're driving in 2nd gear at 25 mph on snow, you're probably around 3k rpms. If you try to make a turn and you let off the gas to do it, you're going to cause the engine to slow the front tires. This uses some of your 'available' friction. Begin turning, and it'll use more. Try to turn too hard, and you're gonna slip.

The best method for driving where traction is an issue is to reduce the overall forces on your tires. Don't turn sharply, don't accelerate/decelerate quickly, and take your time getting places. Oh, and look out for the idiots who will slide right out in front of you because they were going to fast.

Also, don't try to stop using the hand brake. It's much different from using the pedal, and you can easily lock up your rear wheels.

Man, I love the techie! I thought the handbrake was for doing powerslides! LOL :)

ElectricAL 01-05-2013 08:59 PM

In places where it doesn't snow often (and even in places where it does), many people don't know how to deal with a snowy or icy road. If possible, stay home. It's the surest way to avoid a mishap. If you have to travel, follow the advice given above about NOT overdriving your traction. In short, keep speeds slow and maneuvers very deliberate. If you see snowy and icy roads regularly during the winter, consider getting a set of winter wheels and tires so you can swap to the best tires possible for the conditions.

Here in MN, I wish more people used winter tires. After any big snowstorm, there are always many accidents and spinouts.... many that would be preventable if folks were using tires better-suited to the conditions.


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