101–110 of 209 posts
Here are the key takeaways for me: "Thanks to that differential between your axles, an AWD car will send your engine’s power down the path of least resistance—the wheel with the least grip. Where a two-wheel drive car can only choose between two wheels, an AWD system looks for that least resistance across all four wheels." "4WD works by locking the front and rear axles together, splitting torque 50:50 between them. T…
Earlier quoted context omitted.
I always find it suspect when people claim that something is so bad that they cannot find a single concrete thing to criticise it on. I'd suggest you start with the thing you believe they got "most wrong" and go from there. Otherwise this comment seems to lack substance.
Oh there's an absurd amount of concrete things to criticize about this article. I just don't see why I should be giving free editorial services and in effect encouraging what I consider to be blog spam infecting a site I love.
This is a discussion site, meaning we discuss things, telling us a potential problem with the source is a great discussion topic. Taking unqualified potshots at the article doesn't provide a jump-off point to any discuss worthwhile.
Earlier quoted context omitted.
And in the next paragraph "To counteract this [sending of power to the wheel of least resistance] , the better AWD cars are fitted with a center differential that contains a clutch or viscous drive unit. This splits torque front-to-rear, directing it away from the spinning wheel. " So, a well engineered AWD system actually sends power away from the slipping wheel(s) and towards the wheels with traction, which makes m…
That's right. A poorly-engineered 4WD system means you are stuck on a hill because one wheel is on slippery wet leaves. AWD should mean you can get up that hill with three wheels on slippery wet leaves, and one with grip. That's the simplest explanation. I had an old Toyota Tercel 4WD station wagon and it was very difficult to steer sharply at low speed with 4WD engaged because of the lack of a differential. It would…
I think you just said the opposite of the guys above you while saying you agree. 4WD should not have a problem on slippery terrain.
Here are the key takeaways for me: "Thanks to that differential between your axles, an AWD car will send your engine’s power down the path of least resistance—the wheel with the least grip. Where a two-wheel drive car can only choose between two wheels, an AWD system looks for that least resistance across all four wheels." "4WD works by locking the front and rear axles together, splitting torque 50:50 between them. T…
Some of these can be locked manually/physically, but more often these days they are controlled electronically. Of course this defeats any traction control systems, normally leading to a warning light telling you that you are on your own in that regard. Antilocks also often disabled in this mode.
4WD/AWD are almost never necessary in USA and Europe today, to the extent that, if you buy 4WD/AWD you're likely suboptimizing and even taking a risk (for your drivers who aren't familiar with the quirks of 4WD/AWD). As Saab has shown for decades, FWD will get you almost almost anywhere a 4WD/AWD will in bad weather. But sales of 4WD and AWD cars have been a boondoggle for the auto manufacturers. Cost, complexity and…
This is absolutely false. I live in Utah where we regularly get snow measuring feet deep. Driving up the canyon to go skiing, or doing anything in the state during winter or in all the wilderness, it is required by law to have 4WD. All over the west there are roads that are impassable without 4WD. I use it all the time.
I go trout fishing a lot in North Georgia and many places I go would be accessible in a small fwd car. In fact if people saw you driving an incapable vehicle they would stop and warm you about proceeding further.
4WD/AWD are almost never necessary in USA and Europe today, to the extent that, if you buy 4WD/AWD you're likely suboptimizing and even taking a risk (for your drivers who aren't familiar with the quirks of 4WD/AWD). As Saab has shown for decades, FWD will get you almost almost anywhere a 4WD/AWD will in bad weather. But sales of 4WD and AWD cars have been a boondoggle for the auto manufacturers. Cost, complexity and…
I'd have disagreed a few years ago, then I moved to Norway. Snow is normal.
And the average car is simply a FWD. Most folks tend to have cars or station wagons instead of trucks and SUV's, and most of those are FWD.
The biggest things that help in snow?
Snow tires and snow socks for the tires, and chains when necessary. My spouse thought it was nuts that people didn't change tires in the winter, and average travel speeds on roads is slightly higher on snow and ice. Most folks will take their cars lightly offroad without incident (prinmitive vacation houses are often on dirt roads with weedy grass parking). In cities, at least, it is also pretty common to have bins with grit and I think folks need to keep safety items (a shovel) in their cars.
The snow socks are neat, and I wished they were more common in the states. They weren't in Indiana, anyway. http://www.autosock.co.uk/http://www.autosock.co.uk/
There are lots of variations on this theme. There are off-road differentials which limit the speed difference between the output shafts to a fixed maximum ratio, usually in the 2:1 to 4:1 range. It's possible to do some or all of this in software. Tesla has an ordinary open differential but will apply the brake on an overspeeding wheel. Tesla's all wheel drive system has a separate motor for the front and rear wheels…
Is that different than the traction control used by other automakers?
> Tesla's all wheel drive system has a separate motor for the front and rear wheels.
That is very cool. And it sounds much more complex - I wonder if the complexity is worth the benefit.
In real life, in most situations, ground clearance, good tires, traction control and ABS make more difference than driving all four wheels, most of the time. Personally, I'm more concerned with stopping than starting, and that's where ABS and good tires matter and what kind of transmission you have doesn't. This is a sales pitch video, but it is interesting to illustrate the differences in AWD approaches, with differ…
Earlier quoted context omitted.
This is absolutely false. I live in Utah where we regularly get snow measuring feet deep. Driving up the canyon to go skiing, or doing anything in the state during winter or in all the wilderness, it is required by law to have 4WD. All over the west there are roads that are impassable without 4WD. I use it all the time.
The parent and other people commenting about trashing 4WD systems are from Europe. I'm not sure if there are as many remote places in Europe anymore especially compared to Utah. I go trout fishing a lot in North Georgia and many places I go would be accessible in a small fwd car. In fact if people saw you driving an incapable vehicle they would stop and warm you about proceeding further.
Anecdotal evidence makes me claim that electronic traction control systems are excellent, but still no match for good ol' manual systems - probably in part because the automagic systems are easily taken for granted, making drivers forget what icy conditions are like - and using the electronic systems to drive faster, not safer.
There are lots of variations on this theme. There are off-road differentials which limit the speed difference between the output shafts to a fixed maximum ratio, usually in the 2:1 to 4:1 range. It's possible to do some or all of this in software. Tesla has an ordinary open differential but will apply the brake on an overspeeding wheel. Tesla's all wheel drive system has a separate motor for the front and rear wheels…
> Tesla has an ordinary open differential but will apply the brake on an overspeeding wheel. Is that different than the traction control used by other automakers? > Tesla's all wheel drive system has a separate motor for the front and rear wheels. That is very cool. And it sounds much more complex - I wonder if the complexity is worth the benefit.
For AWD, you need a driveshaft and a differential. The differential has a lot of parts, there are a lot of bearings that sap power, and it adds a lot of weight.
Using separate electric motors for front and rear instead increases the available power, enables unlimited torque ratios from all-forward to all-rear, and has many fewer moving parts.