skidding on black ice

[daugen]

IF traction is equal for each rear tire a 2wd vehicle drives with both rear tires and a 4wd vehicle drives with all 4.

Jim, I agree on rwd with limited slip and respectfully disagree with standard 4wd. Of course, what is standard anymore.
I think I need more education...
I thought a "normal" 4wd, like I have on my Suburban is three wheel drive in 4wd High. When I have been in deep snow with the Burb,
in 4wd, not locked up in Low, only one of the front tires spun. If go down into 4wd Low, you bet, they are all pulling.

Couldn't you get a Jeep with three or four different 4wd systems? I always found that remarkably confusing from a marketing standpoint, and
then with a used car, hard to know what is really in it without finding the build info.

Driver skill and decent tires should make a lot more difference in black ice or any ice than sophisticated awd systems. Though the safety braking that is computer controlled in a modern car should help in a skid. At least it's supposed to.

 

[k0ua]

IF traction is equal for each rear tire a 2wd vehicle drives with both rear tires and a 4wd vehicle drives with all 4.

Jim, I agree on rwd with limited slip and respectfully disagree with standard 4wd. Of course, what is standard anymore.
I think I need more education...
I thought a "normal" 4wd, like I have on my Suburban is three wheel drive in 4wd High. When I have been in deep snow with the Burb,
in 4wd, not locked up in Low, only one of the front tires spun. If go down into 4wd Low, you bet, they are all pulling.

Couldn't you get a Jeep with three or four different 4wd systems? I always found that remarkably confusing from a marketing standpoint, and
then with a used car, hard to know what is really in it without finding the build info.

Driver skill and decent tires should make a lot more difference in black ice or any ice than sophisticated awd systems. Though the safety braking that is computer controlled in a modern car should help in a skid. At least it's supposed to.

Drew, I am refering to "standard" 2wd and 4wd in other words, open differentials, on both front and rear, and NO center differential. As for 4hi and 4low. the only thing going on there in a standard system is just a 2 to 1 gear reduction in the transfer case in 4low. There is no lockup or anything else going on. Now that said, there must be dozens of other systems out there with center differentials, fluid couplings, locking front and rear differentials, computer controlled traction control. and on and on. All I am saying is on an "old timey" 4wd system with an "old timey" transfer case when you are in 4wd, both driveshafts are powered from the transfer case, and both front and rear differentials are driven, then you have true 4wd right up to the point that one tire on either the front or rear starts to slip due to uneven traction with the ground. Then you could be down to just 2 tires spinning depending on the ground conditions. Of course in your tractor when you find yourself in this condition, and you press your differential lock, and lock the 2 rear axles together, they will have at least 3 wheels turning, and maybe 4 depending on traction on the front tires. Unfortunately the is not much you can do about the front tires, other than maybe turning the steering wheel to try to find a spot on the ground with more traction.

 

[Egon]

Don't forget the different length drive shafts on the front when figuring things out!

 

[xring100]

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..

M7040/60 And larger have limited slip front diff and with rear diff lock will spin all 4 tires

My buddies massey 5455 has electronic locking differentials. Why would you want true AWD your not trying to perform on a race track. As long as your spinning all tires that's all I need. Most new AWD have multiple clutches to allow torque transfer and allow slippage they can also perform torque vectoring for handling way more complicated than a simple locker

 

[xring100]

Ill wager you wont find a Subaru driver in any of those "displays".
larry

No you find them needing assistance from a jeep and a tow strap pretty typical. Driving 12 tenths of their own ability at about 3 tenths of what the car is acctually capable of

 

[daugen]

No you find them needing assistance from a jeep and a tow strap pretty typical. Driving 12 tenths of their own ability at about 3 tenths of what the car is acctually capable of

too funny, a WRX STI, yeah, he wasn't pussyfooting around. I sure hope he had winter tires on at least; that thing comes with pure summer tires.

 

[xring100]

No you find them needing assistance from a jeep and a tow strap pretty typical. Driving 12 tenths of their own ability at about 3 tenths of what the car is acctually capable of

too funny, a WRX STI, yeah, he wasn't pussyfooting around. I sure hope he had winter tires on at least; that thing comes with pure summer tires.

I'm sure he thought he was ken block right up until the point i watched him stuff it. He had a snow shoes on i did get a look at the tread blocks as i drove by him

 

[daugen]

well you really have to be hotfooting it to stuff an awd car with snow tires on a somewhat plowed road like that.
At least snow drifts don't sue...and often only hurt one's pride.
I bet he just stuffed too much snow underneath and high centered.

 

[daugen]

M7040/60 And larger have limited slip front diff and with rear diff lock will spin all 4 tires

good to know, thanks. I wonder why if we can engage the front diffs with a push of a button, why are we still all
hunting around for a little lever bar on the floor to step on? why not electronic in the rear?

 

[aczlan]

good to know, thanks. I wonder why if we can engage the front diffs with a push of a button, why are we still all
hunting around for a little lever bar on the floor to step on? why not electronic in the rear?

Mechanical lever is cheaper and more reliable.

Aaron Z