Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. Under the Hood. Cite This! Print Citation. Of course, as we began to get into the above, getting power to all four wheels is pretty complicated.
Where a two-wheel drive car can only choose between two wheels, an AWD system looks for that least resistance across all four wheels. To counteract this, 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. Because it does this on-the-fly, automatically, without any driver intervention, good AWD vehicles can help a driver maintain traction through variable conditions.
AWD can go from grippy pavement where the differentials need to allow different speeds side-to-side and front-to-rear to slippery snow, rain, or dirt where torque also needs to be apportioned to wheels with grip , virtually instantaneously. Make sure to look for that number when researching your next car purchase. This provides great traction, but a vehicle locked in 4WD cannot safely be operated on dry pavement because its front and rear axles are forced to rotate at the same speeds.
In addition to potentially causing the vehicle to spin out of control, that also causes a lot of stress on the powertrain and can damage it. Locked in 4WD, a vehicle needs wheel slip to compensate for the different axle speeds—in 4WD, a truck is able to find traction on loose surfaces, but also needs loose surfaces to work.
So you only really ever use 4WD off-road, or in deep snow. While driving around Hollywood, on paved roads, he won't have the front and rear axles locked together. To repeat our previous topic, that means torque is sent to all four wheels, but not split front to rear. This works like an all-wheel system, sending power to the front axle only as needed so the vehicle can be driven in four-wheel on asphalt.
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The differential contains fluid that lubricates and cools the gears. As with any other lubricant, differential fluid breaks down over time. Along with the engine, the differential is very particular about its oil and condition.
You should consider getting your front or rear differential fluid checked more frequently if: Servicing is limited to oil changes at the recommended intervals. The harder you drive, the quicker your differential fluid breaks down.
The grinding of the gears will produce a growling sound and can become louder when taking turns. If this is put off it can result in a major and expensive car repair.
Leak — when there is a leak it means some parts somewhere are not being properly lubricated.
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