{"id":1477,"date":"2024-11-19T11:39:36","date_gmt":"2024-11-19T08:39:36","guid":{"rendered":"http:\/\/www.magaripoa.com\/?p=1477"},"modified":"2024-11-19T11:39:36","modified_gmt":"2024-11-19T08:39:36","slug":"what-is-the-difference-between-4wd-and-awd","status":"publish","type":"post","link":"https:\/\/www.magaripoa.com\/gari\/what-is-the-difference-between-4wd-and-awd\/","title":{"rendered":"What is the difference between 4WD and AWD?"},"content":{"rendered":"

Calvin replies…<\/p><\/blockquote>\n

Great question, as there are a ton of common misconceptions around the differences between (as well as recommended applications of) 4WD and AWD systems.<\/span><\/p>\n

There are many answers here explaining the differences between the ideal application of each (e.g. 4wd is better off road, while AWD makes for better on-road handling), but these answers merely address the differences in the result of each approach, rather than the specific details of how the approaches are mechanically different.<\/span><\/p>\n

The only commonality between the two systems is that power from the engine is routed to both the front and rear wheels of the car, but the similarities end there.<\/span><\/p>\n

TL;DR: Quite simply, the difference lies in what ratio of power is routed to each end of the car, and how that ratio is managed.<\/b><\/span><\/p>\n

The differential or transfer case in the center of the driveline only controls how engine power is routed to the front and rear of the car; differentials at the front and rear axles determine how that power is routed from side to side, and are independent in definition from 4WD or AWD systems.<\/b><\/span><\/p>\n

In either case, to get power to both ends of the vehicle, the engine power (torque) is first transmitted to a device that is responsible for managing how much of that power ultimately makes it to either end. In 4WD cars, the device is a Transfer Case<\/b>, while in AWD cars that device is either a Differential <\/b>or a Transaxle<\/b>.<\/span><\/p>\n

The 4WD Transfer Case<\/b> is a real dummy; primitive and unpretentious, but darn is it reliable! It can\u2019t be bothered with making any kind of decisions as to how much power should go to the front or the rear axle, so it evenly splits the power 50\/50 between the axles when engaged<\/i>. The moniker of \u201cTransfer Case\u201d comes from the requirement that the vehicle operator must choose to transfer power to one or both sets of axles manually and as they see fit, since the device doesn\u2019t do it for them. Later it came to include the fact that the operator also has the option to engage a reduction gearing (\u201cLow range\u201d), which both slows a vehicle\u2019s speed (handy when descending a steep hill or inching over a boulder) as well as multiplies the torque produced by the engine. These latter two features are what lend a proper 4WD system to perform better off-road; because when you are going up, over, or through the nasty stuff, you want to be sure<\/b> that power is going to both axles, and that you are transferring as much power to the ground as possible when in an off-road situation like this:<\/span><\/p>\n

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In many cases, marketers will try to pass off an AWD vehicle as 4WD if the vehicle also has other features that enhance off-road driving, like under-body skid-plating, increased ground clearance, or aggressive tires. Don\u2019t be fooled.<\/span><\/p>\n

The reason you cannot drive around in a 4WD vehicle with the transfer case engaged full-time is because the old, simple T-case cannot accommodate different wheel speeds between the front and rear, so while turning something must break: Either traction between the tires and the road (which is why they chirp and hop) or the vehicle itself (the transfer case and\/or drive-\/prop-\/half-shafts will<\/i> implode if friction does not break where the tire meets the road, as something has to give). In low-friction scenarios like snow or dirt, this is a non-issue.<\/span><\/p>\n

On the other hand, the AWD Differential certainly pretends<\/i> to be smarter than the transfer case, and employs mechanical and\/or computer-controlled electronics to decide when and how much power should be sent fore and aft. However, the reality is that the overall performance of the AWD system depends heavily on the specific type, and in some cases programming, of a given differential.<\/span><\/p>\n

The \u201cDifferential\u201d is very aptly named, as its job is to accommodate the differences in speeds that all four wheels of a vehicle may be traveling at any given time. Unless a vehicle is traveling in a perfectly straight line, all 4 wheels are rotating at a different speed. In a turn for example, the front wheels are traveling at a different speed than the back. Because AWD systems adjust to each wheel\u2019s varying speed, such systems are able to be full-time.<\/span><\/p>\n

There are three types of differentials:<\/span><\/p>\n