Ford Fusion All Wheel Drive (AWD)

[Ford Fusion Team]

Ford Fusion All Wheel Drive

 

 

Ford Motor Company experts clear the air on all-wheel drive vs. four-wheel drive

 

With the addition of the all-wheel-drive (AWD) Ford Fusion and Mercury Milan, Ford Motor Company is now offering affordable AWD technology to a whole new group of customers, bringing it to one of the largest volume segments in the industry.

 

Many of these new customers may wonder why they need AWD on their midsize sedan, especially if they live in a climate where the roads are never icy or snow covered.

 

“Many people think about the AWD system on the Ford Edge the same way they think of the four-wheel-drive (4WD) system on their F-150,” says Ashok Rodrigues, 4WD technical specialist for Ford Motor Company. “There’s been a lot of confusion in the industry as to how manufacturers use the terms 4WD and AWD.”

 

Rodrigues says there are three basic types of AWD/4WD systems, regardless of whether they’re based on front-drive or rear-drive vehicles. Those are part-time, center differential and on-demand.

 

Part-Time Four-Wheel Drive

 

Part-time systems are what most people commonly think of as 4WD. These rugged, traditional systems, found on trucks including the F-150 and Super Duty, feature a simple lock and unlock mechanism that locks the front wheels to the rear wheels. Four-wheel drive is engaged by the vehicle’s operator, usually by flipping a switch or pushing a button on the dash.

 

Part-time systems are almost always marketed with a low-range gear that’s used when maximum torque is needed, for such activities as extreme off-roading or for moving a heavy object.

 

“It’s pretty much a black or white operation,” says Rodrigues. “You either want four-wheel drive or you don’t.”

 

The benefits of this system are its ruggedness and the fact that it’s inexpensive. Four-wheel-drive vehicles are at their best pulling a boat out of the water or hauling a Bobcat back in the woods. The downside is that the system isn’t really adaptable to everyday driving.

 

“With a part-time system, you will inherently bind up when you go around corners,” says Rodrigues. “When cornering, the front wheels want to track a wider arc than the rear wheels. Because all four wheels are locked together physically, you simply can’t do that with part time. It is an inherent part of the design and is fully intended.”

 

Center Differential

 

The V-6 Mercury Mountaineer uses a center differential that constantly splits torque 40 percent to the front wheels and 60 percent to the rear wheels. Unlike the part-time system, the wheels themselves turn at different speeds, eliminating the binding that part-time systems exhibit when cornering.

 

Center differentials need some sort of clutch or limited-slip mechanism to control slip. For example, when the rear wheels begin to slip, the clutch mechanism applies brake torque to the rear axle, sending drive torque to the front axle and keeping the vehicle moving forward. Rodrigues says that traction control can also serve as the clutching mechanism, providing a cost-effective means of applying brakes to the spinning axle.

 

“The nice thing about a center differential is that it’s always sending that torque,” he says, “so you have a very nice refined driving performance. Some people really like those kinds of systems. But they can be heavy, expensive and, as the devices are generally purely mechanical, there simply aren't many tuning options.”

 

On-Demand All-Wheel Drive

 

The third type is the on-demand system. An on-demand system is always driving one axle and then drives the other axle as conditions demand. In the case of the Ford Fusion or Ford Edge, the front axle is the primary drive axle. For the Ford Explorer and Mercury Mountaineer, the rear axle is the primary drive axle.

 

Simple mechanical systems use a clutch to send torque to the secondary drive axle when the primary axle starts to slip. Today’s electronic systems — like those found on all Ford Motor Company cars as well as Ford Explorer and Expedition, the Lincoln Navigator and the V-8 Mercury Mountaineer — use a computer controller that monitors such things as steering angle, accelerator pedal position and engine speed to provide the precise amount of torque, front to rear, as needed.

 

“What’s really impressive about these systems is that they don’t just react to slip,” says Rodrigues. “They usually prevent that slip from occurring in the first place. By predicting slip and preventing it, the driver doesn’t feel the vehicle slipping and responding. The operation is seamless.”

 

He says on-demand systems create a smooth, confident driving feel in all weather conditions with much better traction. The systems also help balance and improve driving dynamics by sending torque to the secondary axle when it’s most appropriate for handling.

 

“On a normal front-drive vehicle, the front wheels have a limited amount of traction available to them,” says Rodrigues. “That traction has to be used for moving the car forward and for steering. If you use all of the torque to drive forward, you don’t have anything left to steer with, and vise versa. An AWD system off-loads some of that drive torque to the rear wheels. The harder you accelerate, the more of that torque that’s going to be redirected to the rear wheels, restoring the ability of the front wheels to steer the vehicle while providing an even higher level of acceleration.”

 

But he cautions that while these sophisticated AWD systems do help with acceleration, they won’t make the car stop any faster.

 

“Your traction is much better and your handling is much better,” says Rodrigues, “but AWD does not give you more braking power.”

[urnews]

Ford Fusion All Wheel Drive

 

 

Thanks for the explanation. We recently (Dec. 4) bought a V6 SEL AWD 2007 Fusion without knowing a great deal about AWD except that is made for better traction and handling. Your post helped to clear up several questions I had. The thing that I don't care much for is the noticeable decrease in gasoline mileage, which you didn't mention. If I had it (the purchase decision) to do over again I probably would not have purchased AWD because we live on the Eastern Shore of Maryland and seldom get much snow here.

[urnews]

The following article comes from WardsAuto, July 10, 2006

 

Ford Develops AWD System In-House

 

DEARBORN, MI – Ford Motor Co. has developed its own all-wheel-drive system for several upcoming sedans and cross/utility vehicles, rather than expand use of the system supplied by Swedish parts maker Haldex AB, Phillip Kurrle, drive line systems supervisor tells Ward’s.

 

The new system will be offered in V-6 Ford Fusion, Mercury Milan and Lincoln MKZ (formerly Zephyr) midsize sedans and Ford Edge and Lincoln MKX CUVs.

 

Kurrle says there are several reasons why Ford decided to develop an AWD system in-house, instead of using the Haldex system employed in the bigger Ford Five Hundred and Mercury Montego sedans and Ford Freestyle CUV.

 

“Trying to get that hardware across the ocean actually would cost us more than making it domestically,” he says. “We were also trying to get something that better fit the application. We were trying to engineer a system that was conducive to the (Fusion/Milan/MKZ) customer (and) flexible enough so we could also put it on the Edge and MKX.”

 

Cost and capacity also were factors in the decision to develop an AWD system in-house, Kurrle says at a media preview here of Ford’s ’07 models.

 

Haldex simply didn’t have the capability to supply the volumes needed for the midsize sedan and CUV programs, Kurrle says, and Ford was able to develop a simpler, more affordable unit.

 

Upcoming Ford Edge to feature internally developed AWD system.

 

The Ford AWD system is similar to that used on the Ford Escape CUV, he says, adding that Ford developed the system independently of its subsidiaries, including Mazda Motor Corp., which engineered its own system.

 

Being able to build the system in great quantities is essential to meeting earlier announced plans to sell 500,000 vehicles with full-time AWD systems annually in the U.S. by 2007.

 

The Ford-developed technology is similar in many ways to the Haldex system, Kurrle says, without revealing exactly what changes were made. “This is a ‘slip-and-grip’ system. It detects the slip of the front wheels and transfers torque, similar to the Haldex system.”

 

The Ford technology, Kurrle says, is simpler than the Haldex system because it is “more electro mechanical (and) the Haldex is more of a pressure, hydraulic-based” system.

 

Despite the simpler setup, Kurrle is quick to point out that the Ford system is “designed and calibrated so it’s got as good a performance as the Haldex.”

 

The system eventually could make its way onto other Ford vehicles, including the Five Hundred.

 

Kurrle, who was wearing a shirt with the logo “4Drive” at the event here, says the moniker does not refer to a potential brand name for the Ford-developed AWD system. Rather, he says 4Drive is an internal slogan.

 

However, Fusion Marketing Manager Dan Geist says there is some ongoing internal discussion as to whether or not to brand the system, but “nothing has been finalized.”

[awdpath]

"Porsche calls this system Automatic Brake Differential (ABD),..."It's a beautifully simple and elegant,..."

 

http://www.whnet.com/4x4/ets.html

 

http://www.fordvehicles.com/cars/fusion/awd/

 

 

 

Traction 2006: Giant winter traction test , Mercedes-Benz C350 4MATIC ranked first:

 

http://www.canadiandriver.com/winter/traction2006.htm

[awdpath]

From the Ford's Workshop Manuals for the 2007 Fusion/Milan/MKZ:

 

 

Traction Control System — All Wheel Drive (AWD) [based on Ford's claims, this feature allows side to side power transfer]

 

The ABS module communicates with the powertrain control module (PCM) to assist with traction control. When the drive wheels lose traction and begin to spin, with vehicle speed under 100 km/h (62 mph), the ABS module requests the PCM to reduce engine torque while simultaneously applying and releasing the appropriate brake caliper(s) to maintain traction. The PCM accomplishes this by minor incremental timing changes and fewer fuel injector pulses until the ABS module ends the request. The request ends when the driven wheel speed returns to the desired speed. After the vehicle speed exceeds 100 km/h (62 mph), the traction control is accomplished only through the PCM torque control. The traction control system can be disabled by pressing the traction control switch and is indicated by the traction control light in the instrument cluster. The traction control system will reset and return to normal operation when the ignition switch is cycled, or when the traction control switch is pressed and released a second time during the same ignition cycle.

 

 

Traction Control System — Front Wheel Drive (FWD)

 

The traction control system is designed to limit wheel spin by modulating engine torque, in order to achieve maximum traction, when driving on slippery or loose surfaces.

 

 

Four Wheel Drive (4WD) Systems — All Wheel Drive (AWD)

 

Principles of Operation

 

The vehicle is equipped with a four wheel drive (4WD) system, also referred to as intelligent torque control coupling (ITCC) , that is always active and requires no driver input. The system has no mode select switch. The system combines transparent all-surface operation with AWD, and is capable of handling all road conditions, including street and highway driving as well as off-road and winter driving.

 

The system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected, or if the vehicle is under heavy acceleration (high throttle position), the AWD system increases torque to the rear wheels to prevent or control wheel slip.

 

The system consists of a power transfer unit (PTU), 4WD control module, rear axle and a solenoid actuated intelligent torque coupling control device. The module varies the torque sent to the rear wheels by sending a duty cycle based on the amount of current sent to the clutch to the active torque coupling device located inside the rear axle.

 

The 4WD control module also provides the brake system with its current clutch duty cycle and whether or not the brake system may take command of the clutch duty cycle.

 

The PTU is a gearbox that attaches to the transaxle. The RH halfshaft passes through the transfer case and engages the differential side gear as in normal front wheel drive (FWD) applications. The transaxle differential drives the PTU. The PTU then drives the driveshaft at all times. The driveshaft drives one half of the rear axle clutch pack. The other half of the rear axle clutch pack drives the rear axle ring and pinion.

 

 

Rear Drive Axle and Differential

 

The differential housing cover uses a silicone sealant rather than a gasket.

 

The halfshafts are held in the differential case by a driveshaft bearing retainer circlip that is located on the inboard CV joint stub shaft pilot bearing housing. When each halfshaft is installed, the driveshaft bearing retainer circlip engages a step in the differential side gear.

 

The rear drive axle operates as follows:

 

The rear axle drive pinion receives power from the engine through the transaxle, transfer case, driveshaft and active torque coupling, and is always engaged. The pinion gear rotates the ring gear, which is bolted to the differential case outer flange. Inside the differential case, 2 differential pinion gears are mounted on a differential pinion shaft which is pinned to the differential case. These differential pinion gears are engaged with the differential side gears to which the halfshafts are splined. As the differential case turns, it rotates the halfshafts and rear wheels. When it is necessary for one wheel and halfshaft to rotate faster than the other, the faster turning differential side gear causes the differential pinion gears to roll on the slower turning differential side gear. This allows differential action between the 2 halfshafts. The right halfshaft is longer than the left halfshaft.

 

The active torque coupling is installed as an assembly with the rear axle.

[RAD_DAD]

Ford Fusion All Wheel Drive

 

 

Ford Motor Company experts clear the air on all-wheel drive vs. four-wheel drive

 

With the addition of the all-wheel-drive (AWD) Ford Fusion and Mercury Milan, Ford Motor Company is now offering affordable AWD technology to a whole new group of customers, bringing it to one of the largest volume segments in the industry.

 

Many of these new customers may wonder why they need AWD on their midsize sedan, especially if they live in a climate where the roads are never icy or snow covered.

 

“Many people think about the AWD system on the Ford Edge the same way they think of the four-wheel-drive (4WD) system on their F-150,” says Ashok Rodrigues, 4WD technical specialist for Ford Motor Company. “There’s been a lot of confusion in the industry as to how manufacturers use the terms 4WD and AWD.”

 

Rodrigues says there are three basic types of AWD/4WD systems, regardless of whether they’re based on front-drive or rear-drive vehicles. Those are part-time, center differential and on-demand.

 

Part-Time Four-Wheel Drive

 

Part-time systems are what most people commonly think of as 4WD. These rugged, traditional systems, found on trucks including the F-150 and Super Duty, feature a simple lock and unlock mechanism that locks the front wheels to the rear wheels. Four-wheel drive is engaged by the vehicle’s operator, usually by flipping a switch or pushing a button on the dash.

 

Part-time systems are almost always marketed with a low-range gear that’s used when maximum torque is needed, for such activities as extreme off-roading or for moving a heavy object.

 

“It’s pretty much a black or white operation,” says Rodrigues. “You either want four-wheel drive or you don’t.”

 

The benefits of this system are its ruggedness and the fact that it’s inexpensive. Four-wheel-drive vehicles are at their best pulling a boat out of the water or hauling a Bobcat back in the woods. The downside is that the system isn’t really adaptable to everyday driving.

 

“With a part-time system, you will inherently bind up when you go around corners,” says Rodrigues. “When cornering, the front wheels want to track a wider arc than the rear wheels. Because all four wheels are locked together physically, you simply can’t do that with part time. It is an inherent part of the design and is fully intended.”

 

Center Differential

 

The V-6 Mercury Mountaineer uses a center differential that constantly splits torque 40 percent to the front wheels and 60 percent to the rear wheels. Unlike the part-time system, the wheels themselves turn at different speeds, eliminating the binding that part-time systems exhibit when cornering.

 

Center differentials need some sort of clutch or limited-slip mechanism to control slip. For example, when the rear wheels begin to slip, the clutch mechanism applies brake torque to the rear axle, sending drive torque to the front axle and keeping the vehicle moving forward. Rodrigues says that traction control can also serve as the clutching mechanism, providing a cost-effective means of applying brakes to the spinning axle.

 

“The nice thing about a center differential is that it’s always sending that torque,” he says, “so you have a very nice refined driving performance. Some people really like those kinds of systems. But they can be heavy, expensive and, as the devices are generally purely mechanical, there simply aren't many tuning options.”

 

On-Demand All-Wheel Drive

 

The third type is the on-demand system. An on-demand system is always driving one axle and then drives the other axle as conditions demand. In the case of the Ford Fusion or Ford Edge, the front axle is the primary drive axle. For the Ford Explorer and Mercury Mountaineer, the rear axle is the primary drive axle.

 

Simple mechanical systems use a clutch to send torque to the secondary drive axle when the primary axle starts to slip. Today’s electronic systems — like those found on all Ford Motor Company cars as well as Ford Explorer and Expedition, the Lincoln Navigator and the V-8 Mercury Mountaineer — use a computer controller that monitors such things as steering angle, accelerator pedal position and engine speed to provide the precise amount of torque, front to rear, as needed.

 

“What’s really impressive about these systems is that they don’t just react to slip,” says Rodrigues. “They usually prevent that slip from occurring in the first place. By predicting slip and preventing it, the driver doesn’t feel the vehicle slipping and responding. The operation is seamless.”

 

He says on-demand systems create a smooth, confident driving feel in all weather conditions with much better traction. The systems also help balance and improve driving dynamics by sending torque to the secondary axle when it’s most appropriate for handling.

 

“On a normal front-drive vehicle, the front wheels have a limited amount of traction available to them,” says Rodrigues. “That traction has to be used for moving the car forward and for steering. If you use all of the torque to drive forward, you don’t have anything left to steer with, and vise versa. An AWD system off-loads some of that drive torque to the rear wheels. The harder you accelerate, the more of that torque that’s going to be redirected to the rear wheels, restoring the ability of the front wheels to steer the vehicle while providing an even higher level of acceleration.”

 

But he cautions that while these sophisticated AWD systems do help with acceleration, they won’t make the car stop any faster.

 

“Your traction is much better and your handling is much better,” says Rodrigues, “but AWD does not give you more braking power.”

[RAD_DAD]

I have a 2007 Mecury Milan V6 3.0L AWD. The car is great and does good in snow. The one area and other people that I know that have the Ford Fusion AWD is the issue with driving on icy road conditions. Ths car feels very unstable. I believe this is do to the AWD kicking in an out. The rear end feels like it gets a little wiggle. There have been a couple of times while going over a bridge the car went a little sideways. Then your heart skips a couple of beats. I'm typically going slower than other traffic so I don't believe I'm driving faster than the road conditions would allow.

I have owned an AWD GMC Safari van and it was full time AWD 60/40 and it never felt unstable.

I would prefer if they provided a way to defeat the AWD during Icy conditions. Maybe the computer has everthing in control but it doesn't feel stable on icy conditions.

 

RAD

[Waldo]

I have a 2007 Mecury Milan V6 3.0L AWD. The car is great and does good in snow. The one area and other people that I know that have the Ford Fusion AWD is the issue with driving on icy road conditions. Ths car feels very unstable. I believe this is do to the AWD kicking in an out. The rear end feels like it gets a little wiggle. There have been a couple of times while going over a bridge the car went a little sideways. Then your heart skips a couple of beats. I'm typically going slower than other traffic so I don't believe I'm driving faster than the road conditions would allow.

I have owned an AWD GMC Safari van and it was full time AWD 60/40 and it never felt unstable.

I would prefer if they provided a way to defeat the AWD during Icy conditions. Maybe the computer has everthing in control but it doesn't feel stable on icy conditions.

 

RAD

 

RAD, that doesn't sound like anything to do with the AWD at all. It's more likely to be either worn tires or poor alignment in the rear. Have your rear toe checked and make sure it's right in the middle of the specification.

[RAD_DAD]

RAD, that doesn't sound like anything to do with the AWD at all. It's more likely to be either worn tires or poor alignment in the rear. Have your rear toe checked and make sure it's right in the middle of the specification.

[RAD_DAD]

No, it is not the tires or the alignment.... I know 3 other people who experience this same condition. It is the AWD engaging. Why would this only happen very seldom. Ford needs to allow you to defeat the AWD option.

[Blizzard35]

No, it is not the tires or the alignment.... I know 3 other people who experience this same condition. It is the AWD engaging. Why would this only happen very seldom. Ford needs to allow you to defeat the AWD option.

 

Hmmmm, I'm not sure I agree...my previous car was a Ford Five Hundred AWD Limited, my current car is a Fusion SEL AWD, I live in Northern Ontario, Canada, you know land of Ice & Snow and I have never experienced anything remotely close to what you're describing. Mind you, I have 4-dedicated ICE & SNOW tires on my car, but I don't know why anyone would want to turn off the AWD system as it only engages "when it is needed" i.e. slippage etc.

[Waldo]

No, it is not the tires or the alignment.... I know 3 other people who experience this same condition. It is the AWD engaging. Why would this only happen very seldom. Ford needs to allow you to defeat the AWD option.

 

It is not the AWD engaging. The AWD doesn't "kick-in", it's constantly on based on speed and throttle input. Unless you're giving it gas as you hit the icy conditions, the AWD will not change. Even driving on the highway in perfectly dry, warm conditions, the AWD will still be on, just with a very low percentage of torque sent to the rear wheels.

 

If you do some searching on this and other forums, you'll find others describing your same symptoms on both FWD and AWD Fusions. The solution has always been alignment or tires.

[wptski]

Hmmmm, I'm not sure I agree...my previous car was a Ford Five Hundred AWD Limited, my current car is a Fusion SEL AWD, I live in Northern Ontario, Canada, you know land of Ice & Snow and I have never experienced anything remotely close to what you're describing. Mind you, I have 4-dedicated ICE & SNOW tires on my car, but I don't know why anyone would want to turn off the AWD system as it only engages "when it is needed" i.e. slippage etc.

Under normal driving conditions "some" torque is always sent to the rear wheels, if slippage is detected, increased torque is sent to the rear. Every time you leave from a dead stop, you have rear wheel torque which slowly decreases till you reach a constant speed. Even on dry hard pavement, if you nail it, rear wheel torque will increase.

 

I've monitored the system at first with a scope but now use a ScanGuage-II coded to show the 4WD PID. This is my first winter doing so and have yet to see/catch increased rear wheel torque due to front wheel slippage, not that it hasn't happened but I've just haven't seen it happen.

 

Don't be fooled as I was with sales brochures. The same exact system is used on the Escape but it's refered to as 4WD.

Edited April 19, 2010 by wptski