Snow doesnt Kill Mileage...

[ShadeTreeMech]

Originally Posted by endurance

..... ABS is great on packed snow and asphalt roads, but on loose gravel and glazed ice the skill of the driver is more important than the technology in the car. ........ Once all four wheels stop turning, the computer thinks you're stopped, so ABS no longer works. You need at least one wheel turning to have ABS work. Unfortunately, most folks don't know that until after the accident.

I now recall the van would lock up at less than 15 mph. But as it was a steep hill, it got over 15 mph easily, then the ABS held me at about 15 mph so long as I let off the brakes long enough to get the wheels turning. If it slowed down too much I had to let up or go into a skid. And it was on glare ice--this was after the ice storm a few years ago that made national headlines.

With as sophisticated as cars are getting, I wonder if the more high tech systems can "learn" the amount of available traction and ease on the brake pressure instead of locking up/unlocking constantly.

[endurance]

Originally Posted by ShadeTreeMech

I now recall the van would lock up at less than 15 mph. But as it was a steep hill, it got over 15 mph easily, then the ABS held me at about 15 mph so long as I let off the brakes long enough to get the wheels turning. If it slowed down too much I had to let up or go into a skid. And it was on glare ice--this was after the ice storm a few years ago that made national headlines.

With as sophisticated as cars are getting, I wonder if the more high tech systems can "learn" the amount of available traction and ease on the brake pressure instead of locking up/unlocking constantly.

My experience is pretty similar; ABS works better at higher speeds. The more expensive systems have speed sensors at each wheel and when an individual wheel is turning slower, it reduces braking pressure at that wheel. As your speed approaches zero the threshold between turning and stopped gets narrower. You can only vary brake pressure so much, thus, your performance near a stop is poorer. With that said, how many of those accidents were over 15mph in the video? Probably few were over 10mph, where ABS works the worst.

In every situation where I've been on true glare ice, I've ended up having to take back control after all four wheels locked. At the same time, we're being told not to pump the brakes and let the ABS do its job. That's all well and good if it does, but I'd really encourage everyone to get out and play in the snow in a nice, big empty parking lot and learn what the abilities and limitations are and how to get the best performance out of your brakes. I was an FTO with a small sheriffs office about 20 years ago and I would always head to the ski area parking lots at night just to run the new officers through their paces on packed snow and ice. Everyone sucks the first time they go into a skid, but after only a handful of times, your reflexes develop and you start making more precise adjustments to your steering and braking.

Far better to practice with no one around than to hit your first icy road of the year with wall to wall commuters.

[bestclimb]

I have used a floored truck to claw my way out, but the ice was very thin and it chewed through the ice to the dirt underneath, so not typical. Chains for the win on ice. may have to go slow but chains on a low fwd car, will beat no chains on anything else short of a tracked vehicle.

[comptiger5000]

t vago - They assume the brakes are the only way to slow down, and that's what I should be using.

IsaacCarlton - I wish my brakes were that strong!

As far as ABS, my system is 3 channel (pulses fronts separately, rear as one due to only one rear brake line). It works pretty well, and I've never locked a tire at slow speeds. Even at 5mph in snow/slush, if I'm braking and one tire goes over an icy spot, I'll get 1 or 2 pulses from the ABS and that's it. Mind you, I rarely kick the ABS due to careful braking, but there are times where it still happens (misjudged traction or slick spots).

Bestclimb - In deep snow where there's a lot of rolling resistance and not enough traction, such as me getting started from a stop in 15" of unplowed snow, sometimes liberal use of the skinny pedal is the only way to do it. Deep snow is a lot like sand and/or mud in that respect.

[IsaacCarlson]

QUOTE: Liberal use of the skinny pedal......


I like that...

[darcane]

Originally Posted by ShadeTreeMech

I think the real cool one is traction control. Only drove one car with traction control, and when I got stuck trying to climb a steep dirt driveway, I just gave it gentle throttle til the car sorted how to climb the hill, which it eventually did.

Traction control has it's limits too. My old Vette had traction control and I absolutely couldn't get up a snowy hill with it, just too slippery (3" of snow and 285/40ZR17 high performance tires area bad combo). Turned it off, and I was able to rock it to get it started and then slip and slide my way up the hill.

[bestclimb]

Originally Posted by darcane

Traction control has it's limits too. My old Vette had traction control and I absolutely couldn't get up a snowy hill with it, just too slippery (3" of snow and 285/40ZR17 high performance tires area bad combo). Turned it off, and I was able to rock it to get it started and then slip and slide my way up the hill.

Had similar issues with a saturn. the traction control nutered engine power on snow, a little slip allows the tires to chew their way through the snow. Frankly if I can't tell my tires are slipping and deal with it I have no business driving.

[darcane]

Originally Posted by comptiger5000

I agree that drivers rely too much on the car's fancy gadgets, and don't actually know how to drive. My Jeep has ABS, but it rarely kicks in, as I typically threshold brake, and stay off the brakes when turning in snow/ice. If/when it does kick more than once or on multiple wheels, that is a signal to ease up on the brakes a little.

It has no traction control, etc. Rear diff is limited slip, front is open. My friends all get freaked out at me driving around in a couple inches of snow and/or slush in 2wd, and that I'm not terrified when it slides a bit around a slushy corner. There are some corners where I'll pop it in 2wd and gas it very lightly to make the rear end slide a bit, then pull it back into 4wd as I clear the corner, as it's far easier to get through the corner that way at 5-10 mph than by crawling 2mph to make the tight, uphill turn and risk getting stuck in deep, icy slush from too little momentum.

People also find it strange that I downshift to slow down, particularly in snow and ice, and will hold a lower gear in the snow. In bad snow, I've crawled down a couple of steep hills in 4lo, 2nd gear to keep my speed down to 5-6 mph without the brakes.

I was taught how to drive in snow the right way: in a big, empty parking lot. I'm only 18, but the extra crap (traction control, stability control) is just annoying IMO, and impedes the driver's ability to actually drive the vehicle.

On the rare occasion I'm in a 4wd, I always drive in 2wd until I get to a point where I can't get further in 2wd and then use 4wd to get unstuck, then put it back in 2wd and continue on. Relying on 4wd all the time tends to get you into a situation that is REALLY bad.

I've only owned 2wd vehicles since I don't go offroading and I have only once been in a situation where I needed 4wd on a regularly maintained road. And I've been in some nasty situations. Good tires will get you anywhere you need to go.

You seem to be a far better driver than most kids your age. Just remember you always have more to learn, so don't get too cocky out there.

[comptiger5000]

Thanks! I have been told by quite a few people about the 4wd only when needed trick, which definitely works. "2wd gets you stuck, 4wd gets you stuck worse".

I think part of what helped, particularly as far as winter driving, was that when I was learning to drive, my dad made me push various vehicles to their limits, including plenty of time spent in parking lots. Plus, it helps that the Jeep has fairly balanced (and very predictable) handling (mild understeer, easily countered with throttle in either 2wd or 4wd).

[MetroMPG]

More: "why didn't someone go to the top of the hill to warn them" icy roads mayhem...

http://www.youtube.com/watch?v=6249iHSJsKo