TRENTO MOTORS

Subarus All-Wheel Drive System is always on, watching out for your safety while driving. "Subaru full-time, All-Wheel Drive provides outstanding traction on almost any wet or dry surface, in any weather. Subarus AWD constantly monitors road conditions, sensing loss of traction and automatically transfers power from the slipping wheeles to the wheels that have grip. Everyone will agree wheels that grip are especially nice if you're into skiing or any other sport that demands a lot from a vehicle or simply living in a rural area. Like rally racing, where Subaru is a consistent champion, proving itself year after year, dominating the competition on some of the world's most challenging courses.

You can count on Subaru All-Wheel Drive to be working for you, full time.

Subarus All-Wheel Drive System is all about different components working together to keep you safely on the road, however, there are four parts that constantly demonstrate their independence. The wheels.

Subarus long travel four-wheel independent suspension handles rough roads, unexpected dips sharp turns and bumps beautifully. Because each wheel is on its own, allowing the suspension to absorb road irregularities and keep each tire firmly planted on the road. Thats why any off road sports enthusiast will tell you that Subaru is the way to go to tackle the demanding road conditions. Sheer stability is what you get when each wheel has a "brain of its own".

Anti-lock disc brakes come on almost every Subaru. They're designed to not lock up on you. Step hard on the brake pedal and you'll feel the Anti-Lock Braking System (ABS) automatically help balance braking for better control and safer, more even stopping.

"Safer stopping power. Keeping you safely on the road, not fishtailing off it. That's what the Subaru Anti-Lock Braking System is all about."

"After all this talk about active safety, let's talk passive safety features. These are the safety features built into every Subaru that we hope you'll never have to use. But everyone knows accidents can happen".

"First, there's the rigid unibody construction, which reduces flex and makes your Subaru one strong machine. Then there are the front and rear energy-absorbing crumple zones, which absorb a lot of the impact in a collision so YOU don't have to. Same for the side impact door beams. And, of course, dual front air bags* come standard on every Subaru model.

*The Supplemental Restraint System (air bag) provides additional protection in a frontal collision. This system provides supplemental protection only, and seat belts must be worn in order to avoid injuries to out-of-position occupants upon bag deployment and to provide the best combined protection in a serious accident. Children should always be properly restrained in the back seat.

Subaru Drivetrain

All Subaru models sold in Canada and the U.S. feature the Subaru All-Wheel Driving System. This system consists of several subsystems working in harmony to ensure maximum traction availability without any driver input. Unlike many four-wheel drive or all-wheel drive systems, the Subaru all-wheel drive system consists of power transfer mechanisms that are small enough to fit inside the transmission case. These small components not only hold down weight and power loss, but also ownership costs of Subaru vehicles, as no extra maintenance is required for the system.

Subaru all-wheel drive works differently in manual and automatic transmissions. Read on for more technical information.

All-Wheel Drive (Automatic Transmission)

Active all-wheel drive is a term coined by Subaru to differentiate the all-wheel drive system in the automatic transmission from other "reactive" all-wheel drive systems on the market today. What makes this all-wheel drive system so special is its ability to anticipate traction needs and act before a wheel slips.

The mechanism that transfers torque fore and aft is contained within the transmission's tailshaft. To the casual observer it looks just like a typical hydraulic clutch found in any automatic. The key difference in this clutch pack is its operation. It's designed to slip according to how much all-wheel drive is needed. When an automatic's clutch slips, it is due to a malfunction and will eventually burn up. But the multi-plate transfer (MPT) clutch uses a special friction material that easily withstands the friction loads generated during torque transfer.

The MPT's operation is controlled by the Transmission Control Unit (or TCU) and constantly changes dependent on how the vehicle is being driven. To get more all-wheel drive, the TCU increases the hydraulic pressure to the clutch for less slippage. Less all-wheel drive calls for more slip and the TCU reduces the hydraulic pressure to the clutch.

Under normal, dry pavement operation torque split is about 90% front and 10% rear. This distribution helps to compensate for the car's weight distribution and resultant smaller effective rolling diameter of the front tires. As weight transfers to the rear of the vehicle, (i.e., under acceleration), the TCU shifts the torque split more toward the rear wheels. Under hard braking, torque is directed forward. Torque distribution is changed based upon how the vehicle is being driven. Throttle position, gearshift lever position, current gear and other factors combine to influence the TCU and it, in turn, selects a software map that determines how aggressively torque split will be adjusted.

Two speed sensors are used by the TCU to detect wheel slippage. One sensor monitors the front axle set, the other the rear axle set. Pre-programmed variables help the TCU differentiate between slipping wheels and normal wheel speed differentials as what occurs when cornering. A speed differential (front-to-rear) of up to 20% signals the TCU that the vehicle is cornering and torque is distributed to the front wheels to help increase traction during the turn. Anything above 20%, however, indicates to the TCU that wheel slippage is occurring and torque is then distributed to the rear wheels.

Another feature of the all-wheel drive system is its interaction with the anti-lock brake system. When ABS is engaged, the transmission selects third gear, reducing the unpredictability of engine braking and, thus, reducing the possibility of wheel lock-up. But all four wheels are still connected to the engine through the AWD system and are brought back up to overall vehicle speed quicker and can, therefore, be controlled again sooner. In a two-wheel drive system if the locking wheel isn't a drive wheel, it can only be brought back up to overall wheel speed by whatever traction exists between it and the road. The quicker a wheel is controlled the better the stopping performance

All-Wheel Drive (Manual Transmission)

The 5-speed manual transmission's all-wheel drive is referred to as a continuous all-wheel drive system. It uses a center differential located inside the transmission case that is controlled by a viscous coupling device. In effect, the center differential is a limited-slip differential.

In normal operation, power is distributed equally to the front and rear wheels. Plates are alternately attached to the front and rear output shafts inside the viscous coupling. When a rotational difference occurs between the front and back wheels, the plates inside the viscous housing shear inside the contained fluid (a type of silicone) heating it and causing the fluid to thicken. The thickened fluid causes the plates to transfer torque from those that rotate faster (the slipping wheels) to the plates that rotate slower (the wheels with the best traction).

This no-maintenance system is simple, compact and virtually invisible in its operation. The system can distribute torque from a 50:50 torque split for maximum traction to mostly front or rear wheel drive

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Thank you,

To all who provided their input.

Which drive-train system is best for your vehicle? It depends on the vehicle, how you drive-and where you plan to drive it.

Two-wheel drive comes in two different trims: rear-wheel drive (RWD), and front-wheel drive (FWD). All things being equal, two-wheel drive vehicles are lighter and more fuel-efficient than comparable four-wheel-drive vehicles.

Rear-wheel drive is used on many trucks and truck-based SUVs. It lends itself to pickup trucks, which often carry a big load over the rear wheels. Sports cars and other performance-oriented vehicles typically use rear-wheel drive as well, due to enhanced weight distribution and handling characteristics.

Front-wheel drive is increasingly common on passenger cars and car-based SUVs. Front-wheel drive is typically lighter, more economical and efficient, provides excellent overall traction and performance, and generally allows for a roomier interior when compared to a RWD vehicle of the same external size.

Modern electronic traction control and stability control has typically made two-wheel-drive vehicles considerably safer and generally easier to drive in challenging driving conditions than ever before.

Front-wheel drive is available on the Suzuki XL7, SX4 Crossover,and SX4 Sport.

Rear-wheel drive is available on the Grand Vitara.

Four-wheel drive is typically used on vehicles that might be traveling off-road or on slippery surfaces like snow, sand and gravel, where increased traction is highly desirable.

Most four-wheel drive vehicles give you multiple options of power delivery to the wheels to best fit the terrain: High- and low-range gearing, and lock/unlocked mode.

High-range gearing is suitable for normal driving speeds and conditions. Low-range gearing engages a special reduction gear that increases torque while trading off speed. This gearing can assist you in getting through tough situations, but it's typically not suitable for normal traffic speeds.

4WD systems use a center differential to send power to both the front and rear wheel sets all the time. But while the vehicle is turning, the rear wheel set tracks slightly different from the front wheels, thus the center differential needs to process a slight difference in speed between front and rear wheels.

To gain maximum traction in challenging conditions such as snow, sand, and other loose surfaces, most center differentials have "lock" mode which locks the front and rear wheels to spin at the same speed. Lock mode generally allows the power to be evenly distributed to the front and rear wheel sets for maximum traction. However, due to this very fact, some surface slippage between the tires and the terrain is necessary to prevent excessive tire wear, less responsive steering, or hopping.

The Suzuki Grand Vitara offers a rugged full-time 4-Mode 4WD, with limited-slip type center differential with a low-range transfer case. Unlike other compact SUV's that make do with AWD, the Grand Vitara can go where these wanna-be's don't dare.

In 4High-mode, 4WD system acts like an AWD system, and optimizes traction for on-road car-like performance and safety.

4High-Lock mode is designed to give greater traction in demanding conditions like snow or mud. This is achieved by locking the center differential to send equal power to the front and rear wheels, minimizing wheel spin.

4Low-Lock mode engages the low-range gears for transfer of maximum power and traction to handle the toughest of terrains.

Neutral disengages all four wheels for flat-towing. This mode helps provide less wear and tear should you tow your Grand Vitara behind your RV, and it also means you don't accumulate miles on the odometer.

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What is the difference between "four-wheel drive" and "all-wheel drive"?

Good question.

All-wheel drive usually does not require the driver to switch manually into a four-wheel-drive mode when the driving gets tough or slippery-the system reacts automatically, depending on the condition. Conventional all-wheel-drive systems rarely have a low range gearing.

This makes all-wheel drive a good choice when a vehicle will seldom be used in extremely rough driving conditions-conditions which might require the extra traction and torque of a four-wheel drive system with a high/low-range transfer case.

All-wheel drive can be beneficial in high-performance automobiles, which make use of all four wheels to get all the traction and control possible over fast-changing terrain.

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AWD is available on the Suzuki XL7. The Suzuki SX4 Crossover is available with innovative 3-mode intelligent All-Wheel-Drive (i-AWD), which allows the driver to choose between efficient 2WD, 4WD Lock which locks the wheels together for slow going in mud, sand, ice or snow, and versatile 4WD Auto, which automatically apportions power to the rear wheels when needed for additional safety and performance.