All-wheel drive and four-wheel drive explained

Some variants of the big Mercedes, Porsche, Audi and VW SUVs take those. Range Rovers too.

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10

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Do those have some sort of built-in camber? Or is that just camera perspective?

Just the camera. Here’s a different picture of the same BFG tires.

They’re only for off road snow and ice racing, not road use. For more practical ice and snow driving if you don’t want to put proper snow tires on, you can get tire chains from most auto shops.

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I thought this one was shorter and better. https://youtu.be/yPZmP4JWJcg

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Subaru SVX: underappreciated.

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Way better. That video explained at least partly what they are for, rather than just repeating a description of how they work over and over.

But it still fails to explain why 4WD would ever be better…

Heh, so far I haven’t found anything about why 4WD would be better at anything other than:

It’s simpler, so probably cheaper and more reliable.

It’s the thing they put on most vehicles with other off road features like high clearance.

It usually also has a low range built in, so you can get significantly lower gears. That would at least be a whole separate feature to put on top of AWD.

I guess because it’s is so simple the driver has more direct control of what the wheels are doing. Maybe that is useful to people who know how to drive off road?

Traditional 4WD is no good at all on sealed roads. AWD allows 4WD to be engaged all the time, not matter the surface so it is always switched on when you need it. No reason why a traditional 4WD can’t be similarly equipped except it would be even heavier and more expensive.

I’m the video hastur posted the guy says they are some vehicles that are AWD, but you can lock them into 4WD for serious offroading… But no explanation as to why you would do that or why it would be better for anything.

Another example of always-on all-wheel drive:
image

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The Platonic opposite of winter tires…

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Wait why the hell is there a brake?

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Touring unicycles often have brakes; helps on the long downhill bits.

A friend of mine crossed Tasmania on one.

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Okay. I have never seen one that coasts.

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They don’t coast, it’s still direct drive; has to be in order for you to balance it. But on a very long downhill without brakes, it’s possible to get tired enough for your leg “brakes” to fail.

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Ahh or where I would say fuck it I am walking.

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I’m sore just thinking about touring on a unicycle, and I’m a lifelong cyclist.

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AWD in some vehicles can allow a wheel to spin and take all the power while letting the other wheels that are actually in contact lose their power.

4WD locks the axles so all the wheels turn together. So if you have your front wheels off the ground, they won’t spin and take all the power off the engine leaving the rear wheels dead. Instead all 4 wheels will turn at the same rate so even if the front wheels are off the ground the rear wheels will still have the same power they normally do.

AWD, by its nature of always being on, needs to have slip or give in the differential. This means if you have wheels that are free spinning they’ll usually take up all the power leaving the contacting wheels out of power and generally useless. So if you’re in a ditch, you may have trouble getting out with AWD due to front wheels slipping, while 4WD doesn’t care if the front wheels slip and will keep turning the rear wheels at the same speed as the slipping front wheels.

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The explanatory video said that power is shifted away from the wheel that is slipping most with AWD (though there are now many different AWD’s, so there may be no simple answer).

Is that good only for 1 wheel, and thus not good enough for serious off-roading?