skidding on black ice

[k0ua]

Daugen do you understand the relationship of the pinion and ring gear and the spyder gears and bevel gears on each axle shaft? If not, please look at this old video that explains it well.
If you brake the spinning wheel a bit it will slow it down, and slow down the rotation of the spyder gears, allow more "push" on the opposite bevel gear on the opposite axle. Remember if the both bevel gears are rotating at the same speed, the spyder gears are not rotating at all on their jackshafts.

Around The Corner (1937) How Differential Steering Works - YouTube

 

[aczlan]

Aaron, ok, so you brake the spinning wheel, but if that does not increase the torque to the non spinning wheel, what have you accomplished other than forcing rpm reduction down to some sane level where traction might be gained?. I thought an open diff sent power to the first wheel that will spin. ?

What it does in increase the torque needed to spin the wheel that has no traction so that increases the amount of torque sent to the wheel that has traction.

A closed diff or limited slip diff would actually drive two wheels, not one.

It can also put you sideways real fast if both back wheels break loose (have done that on purpose a time or two in my limited slip equipped '97 Volvo V90)

It used to be easy to order positraction or whatever marketing term the big three had at the time, but today it seems you have to order only the highest performance rear wheel drive model to get limited slip on the rear. Instead, it's all electronic nannies and braking control.
And even harder to find on fwd cars.

Thats because telling ABS to slow the spinning wheel is just a few extra lines of code in the ABS software. Adding limited slip takes hardware which costs a lot more.

Aaron Z

 

[k0ua]

Thats because setting ABS to slow the spinning wheel is just a few extra lines of code in the ABS software. Adding limited slip takes hardware which costs a lot more.


My truck has all 4 systems. ABS, Traction control, Stability Control, and a mechanical type of locker called the Eaton G80 or "gov lock"

 

[xring100]

well, good info. But ABS is not defeatable in most cases so we need to know how to drive with it properly.
Yes there may be a rocker switch somewhere on a person's dash, but I defy you to find someone, other than us motorheads, who
knows what it means or what it does. they are going to slam on those brakes in a skid. BUT WAIT. Not in a FWD car. Need to get that word out...

Sure it is pop the abs pump fuse out (high amperage), abs disabled. Or pull 2 abs wheel speed sensor wires. Usually there is also an abs module fuse I wouldn't pull that one or you also loose all dynamic proportioning definitely bad if you go rear bias. Lock the rear wheels before front in a panic stop and you will experience spinning while braking. Same thing could also happen while braking in a turn (spinning in a turn) as a brake engineer I don't recommend doing any of the above. Most people in a panic situation will not out perform abs. Though it is possible

 

[ultrarunner]

Anyone remember the old Jeep Wagoneer ad with quadratrac?

They would position the jeep with one front and the opposite rear corner wheel completely in the air and then drive... no spinning and no fancy electronics.

This was 40 years ago.

 

[daugen]

4wd is such a misnomer.
Normal: one wheel drive
4wd: two wheel drive
4wd with locking/limited slip rear: 3 wheel drive
AWD: true four wheel drive

do I have that correct?

Been driving my Kubota in the snow a lot this winter (no surprise!) and despite 4wd, have had to step on the diff lock numerous times to get myself though heavy snow with a load on. Need that 3 wheel drive...
Wonder if any tractor is true awd? probably too expensive..

 

[daugen]

Black ice is one reason why I study TireRack.com carefully. There are many good winter tires, and even some all season ones that have capability on ice.
Has to do with the silica and other gritty things I suppose they put in the rubber compound, which is also designed for low temps.
The Continental PureComp radials I put on my VW recently have that compound in them, and so far, they have been awesome this winter for a normal
all season tire, albeit one I researched carefully to do well year round. I have a 4wd Suburban for nasty weather, don't need snow tires on the car. And the tires on the Suburban, Firestone AT's, are amazing in the snow, but probably not as good on ice as the car. Now I just stay off the roads unless it's a true emergency. And since I don't have a blue light on my car anymore, unlikely that will happen.

The worst ice driving experience I've had was about thirty years ago here when everything was just a skating rink, about half an inch of solid ice on everything.
I don't know why I had to go out, maybe the fire company, don't remember. But I do remember driving down the very center of the road, trying to balance myself on the crown of the road, as our secondary roads are highly crowned for drainage, and there is a tendency to slip to the right. Since no one else was out on the road, I just very slowly crept down the center of the road to home.

 

[Egon]

<The worst ice driving experience I've had was about thirty years ago here when everything was just a skating rink, about half an inch of solid ice on everything.
I don't know why I had to go out, maybe the fire company, don't remember. But I do remember driving down the very center of the road, trying to balance myself on the crown of the road, as our secondary roads are highly crowned for drainage, and there is a tendency to slip to the right. Since no one else was out on the road, I just very slowly crept down the center of the road to home.>

And then came the super elevated curve and you were driving to slow!

 

[aczlan]

4wd is such a misnomer.
Normal: one wheel drive
4wd: two wheel drive
4wd with locking/limited slip rear: 3 wheel drive
AWD: true four wheel drive

do I have that correct?

As I understand it, AWD is no more "true 4WD" than any other vehicle. They still have differentials, there is just a limited slip differential between the front and rear wheels instead of a locking shaft that doesn't allow any slip and generally they use traction control braking to control wheelspin.

Wonder if any tractor is true awd? probably too expensive..

Some have locking front differentials, but those are generally 100HP or larger.

Aaron Z

 

[ericher69]

Before spewing incorrect "knowledge" please do your research. There have been many tests to confirm what I have posted and it is common knowledge among anyone educated on the subject. Anti-lock braking system - Wikipedia, the free encyclopedia There is lots of good info out there, read it.

Obviously your first issue is believing Wiki...

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