****DEEP BREATH****** (this is going to be long and painfull)
I taught winter driving skills for about 9 years. I also taught performance driving. I have also ice raced my Jeep for about 12 years.
There has been some good advice in this thread, but there has also been some 1/2 good advice and some stuff that will get you killed. The winter class I taught was 1-2 days long depending on which course you took. So I will try to just point out a few things here.
You need to understand one basic premis for this. Traction. Your truck has "100 units" of traction. You can use all 100 anyway you want but not more. If you try to use 101 units the truck will slide. The fastest most efficient way to do anything in a car is to ONLY do that one thing. Use ALL 100 units for braking OR use ALL 100 units for turning. (Or ALL for accelerating). You can combine the actions but you reduce the efficiency of each. (Use 60 to brake, 40 to turn etc)
1) Pumping the brakes! This is a perfect example of the "grapevine" effect. One person telling another person telling another until it comes out completly wrong and mis-understood. It was originally taught as "threshold braking". In VERY short terms. Brake with all available traction All 100 units. The threshold is the point where the tires start to slide. Once you reach that point you want to release just enough pressure on the brakes to allow the tires to roll again(back down to below 100 units). Once they are rolling you can give some more pressure to make sure you are at that maximum braking point(if you released to 85 units give a touch more to nudge back up to 100). The amount of pressure you release could be equal to just relaxing a toe, NOT releasing the brakes. Why would you ever want to stop braking if you are trying to stop? This whole process of pressing, easing up, adjusting the pressure on the brakes has through the grapevine turned into "stomp, release, stomp....or pumping the brakes"
For maximum braking you CAN NOT turn the steering wheel. This will request more from the tires. If you need to turn quickly TAKE YOUR FOOT OFF THE BRAKES!!! This will free up all 100 units of traction to be used for steering giving you the best steering response.
"Anti-lock brakes" were never designed to stop a car in a shorter distance. They were designed to give a driver some units of traction to steer the car with. Many people would lock up the brakes. (use more than 100 units of traction) and then expect the car to turn. (0 unit left to make the car turn). ABS senses that you have locked up the brakes and the system releases brake pressure to give some traction units back for steering. (for this converstation let's say it give you 15units back) That quickly builds back up since you have your foot planted on the brake pedal. So the system releases pressure again. This is the sensation you feel in the pedal. You build up the pressure and the system releases it. Since it releases it to a point below the max braking point (threshold) In most cases you can still stop an ABS equiped car in a shorter distance by threshold braking. (braking as hard as you can without the ABS coming on).
We did this on a skidpad at 20 mph. From 20 you can consistantly stop a car with threshold braking 2-3 car lengths shorter than ABS and 4-5 lenghts shorter than just pounding the brake and sliding.
*****Deep Breath Again.....ready for more?******
"Turning into the skid"......IS WRONG!!!!
Okay, now that I have you fired up. The act of "turning into the skid" only works about 60% of the time. You may indeed turn into it in some cases but there is a MUCH better way to think about it.
First you need to know WHY skid and spin recovery work. (yes, they are different). If you try to push a car sideways you encounter lots of friction. Tires were not meant to go that way. If you try to push a car the direction the tires roll, it works pretty easy.
Here is how a skid recovery works.
Imagine driving down a perfectly straight level road. The car starts to slide. This means that the tires are now dragging some degree of sideways down the road. By turning the tires the direction you want to go. (in this case down the road, and yes into the skid) you are letting the front tires roll the direction of the road while the back tires are draging along it. This means that the front of the car will travel faster than the back. This is what makes a skid recovery work. In order for this to work you can NOT use the brakes or the gas. This defeats the physics. You want all available traction to steer. once you are going straight you can use the brakes again.
Now here is where "steering into the skid" starts to go wrong. Take your flat straight road and tilt it and put a curve in front of you(with a cliff of course
). The truck starts to slide toward the curve and cliff. If you steer into the skid you are steering yourself off the cliff.
If you steer where you want to go. Which would be along the curve, not off it. All four of your tires will be draging along the roadway causing more friction and slowing the car down faster. The instant the speed decreases to the point where more traction is aavailable the car will proceed forward along the roadway. (where you were pointing it) Again, for this to work the ONLY thing you want to be doing is steering.
The point here is this. "Steering into the skid" as a phrase can get you into trouble. You really only do this part of the time. "Steering where you want to go" will get you there every time. (even though some of that time you are technically steering into the skid
)
I would suggest if you go to a parking lot to try this. Take a set of cones with you. Creat a "goal" along a "roadway" and try to steer thought the goal. Don't just go do donuts in a parking lot. The old phase "practice make perfect" is WRONG, "perfect practice makes perfect". If you don't practice something right, you are simply training in the wrong skills.
"Spin Recovery"
If you are driving down a road and you start to slide. There is a point where "steering where you want to go" (or for the ney sayers "steering into the skid") will no longer work. At the point where you are 90 degree to your original path of travel. Having the wheels pointed any direction but straight will actually accelerate the spin. You need to return the front wheel to perfectly strraight. (in line with the back wheels) this will cause all four tires to drag the roadway again, and will stop the spin at 180 degrees (or 360 if you don't catch it fast enough). This only works with NO braking. Granted you will be traveling down the roadway backwards. But you will have steering and braking control again. Trust me on this one, works like a dream even at 150 mph on a race track.
I tried to cover this in a concise manner. So I may have skipped something and I am sure there may be a question. I did the math one day and figured out that I have done more than 30,000 skid/spin recoveries on a skid pad teaching people how to do this. I have had grown men argue the hell out of this until they go try it on a skid pad multiple times.
The problem most people have is that they can't duplicate any skid to make sure they actually did the right thing on purpose or if it was luck.
One last thought. THE ONLY thing 4 wheel drive does for you is reduce the work load of each tire. If you have a 4,000lb truck in 2wd with open diffs. 1 tire has to puch 4,000lbs. If you put it into 4wd. You now have 2 tires working and each only has to push 2,000lbs. This is what makes it easier to get moving. This gives the driver the perception that the road is not as slick. You still have the same four tires at 100 units of traction for braking and steering.
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..guess I'll have to change them SOON!...big "monster" tires SUCK in snow in my opinion,I use stock height skinny tires ,and can plow deep snow the "Bigfoot" trucks just sit and spin on, and go sideways ,with their big tires..
