Ford's AWD vs Haldex AWD

[metroplex]

I understand that Ford uses their own in-house AWD for the Fusion. Does anyone know if it is identical to the Haldex LSC/PTU setup found in the 500/Taurus AWD, or if it is a completely new design?

 

I looked at the Haldex website and it appears the LSC would allow for limited slip action (although many of the car sites do NOT recognize the AWD as having LS differentials for some reason), but it is unclear if the rear wheels would have some type of limited slip differential. I recall a board member saying that the Fusions have an eLSD rear-differential. This sounds SIMILAR to GM's G80 locker that uses mechanical parts to engage the clutch packs at certain speeds.

 

I live in Southeast Michigan and have been braving the snow for the past 5 years with my 2000 Crown Vic w/ snow tires and a Traction-Lok rear differential. I am definitely going to buy an AWD car in the future but it is a split between a Subaru (probably an Impreza WRX or STI or the Legacy GT 2.5) and the 2009-2010+ Fusion (whenever they get dynamic stability control AND a more powerful engine). However I want a true AWD and not some BS with an open differential here and an open differential there.

 

I have contemplated going for a test drive at a local dealership when there is heavy snow so I could test it out myself but I am not sure if the salesperson would appreciate it.

 

So how does the AWD feel in the snow? Do you get excessive understeer? Does it react quickly? Do I *need* snow tires for 8"-10" of snow w/ the AWD?

[Jimmy G]

I understand that Ford uses their own in-house AWD for the Fusion. Does anyone know if it is identical to the Haldex LSC/PTU setup found in the 500/Taurus AWD, or if it is a completely new design?

 

I looked at the Haldex website and it appears the LSC would allow for limited slip action (although many of the car sites do NOT recognize the AWD as having LS differentials for some reason), but it is unclear if the rear wheels would have some type of limited slip differential. I recall a board member saying that the Fusions have an eLSD rear-differential. This sounds SIMILAR to GM's G80 locker that uses mechanical parts to engage the clutch packs at certain speeds.

 

I live in Southeast Michigan and have been braving the snow for the past 5 years with my 2000 Crown Vic w/ snow tires and a Traction-Lok rear differential. I am definitely going to buy an AWD car in the future but it is a split between a Subaru (probably an Impreza WRX or STI or the Legacy GT 2.5) and the 2009-2010+ Fusion (whenever they get dynamic stability control AND a more powerful engine). However I want a true AWD and not some BS with an open differential here and an open differential there.

 

I have contemplated going for a test drive at a local dealership when there is heavy snow so I could test it out myself but I am not sure if the salesperson would appreciate it.

 

So how does the AWD feel in the snow? Do you get excessive understeer? Does it react quickly? Do I *need* snow tires for 8"-10" of snow w/ the AWD?

 

Mine handles great in the snow. I've posted before on what it does. There is no lag when accelerating from a dead stop. With the TC off, the rear end kicks out a little on acceleration just like my F-150 4X4 that has a posi rear end and 4X4 engaged. TC on and it's arrow straight. I've done donuts in a parking lot with the TC on and off. With it on I noticed the rear anti lock working but still slid pretty well. With the TC off it spun easily. I would say leave the TC off and pedal it if you're worried about understeer.

[metroplex]

Mine handles great in the snow. I've posted before on what it does. There is no lag when accelerating from a dead stop. With the TC off, the rear end kicks out a little on acceleration just like my F-150 4X4 that has a posi rear end and 4X4 engaged. TC on and it's arrow straight. I've done donuts in a parking lot with the TC on and off. With it on I noticed the rear anti lock working but still slid pretty well. With the TC off it spun easily. I would say leave the TC off and pedal it if you're worried about understeer.

 

What about the front wheels and rear wheels when you get slip? Do you only get slippage on one front wheel and one rear wheel? Or one front wheel and both rear wheels, or all 4 wheels?

 

I looked through the 07 500 AWD's FSM (before it was called the Taurus) and it appears to use a transaxle for the front wheels, followed by a PTU (Power transfer unit) that transmits power via driveshaft to the rear differential, which is a viscous coupling limited slip that is electronically controlled/engaged by the active coupling module. This appears to be a bona fide Haldex unit (says HALDEX on the pan in one of the diagrams), and Edmunds shows similar specs for the Volvo S80, Ford Edge, and Audi A4 which all use Haldex units.

 

The front transaxle, OTOH, doesn't seem to have a limited slip differential.

 

BTW, how deep was the snow you drove through and did you need snow tires? How fast were you able to go on the snow?

[Jimmy G]

What about the front wheels and rear wheels when you get slip? Do you only get slippage on one front wheel and one rear wheel? Or one front wheel and both rear wheels, or all 4 wheels?

 

I looked through the 07 500 AWD's FSM (before it was called the Taurus) and it appears to use a transaxle for the front wheels, followed by a PTU (Power transfer unit) that transmits power via driveshaft to the rear differential, which is a viscous coupling limited slip that is electronically controlled/engaged by the active coupling module. This appears to be a bona fide Haldex unit (says HALDEX on the pan in one of the diagrams), and Edmunds shows similar specs for the Volvo S80, Ford Edge, and Audi A4 which all use Haldex units.

 

The front transaxle, OTOH, doesn't seem to have a limited slip differential.

 

BTW, how deep was the snow you drove through and did you need snow tires? How fast were you able to go on the snow?

 

As far as wheel slippage, I can't really tell from inside the car. I've had front wheel drive cars (SHO), 4X4 pick ups with posi rears and rear wheel drive cars with posi rears. With the TC off the rear kicks out like all the posi rears I've driven in the snow so take it from there. The snow in the parking lot was 8 or 9 inches. The snow on the road was NOT freshly plowed and it was drifting. I was going at a safe speed for the condition on the road. The car has the tires it came with and I'm happy with their performance in the snow. I've got a drive shaft carrier bearing going out and when it gets replaced I'd like to look at the setup under the car to see what's there. The mech working on it doesn't seem to think it's a HALDEX unit.

[metroplex]

As far as wheel slippage, I can't really tell from inside the car. I've had front wheel drive cars (SHO), 4X4 pick ups with posi rears and rear wheel drive cars with posi rears. With the TC off the rear kicks out like all the posi rears I've driven in the snow so take it from there. The snow in the parking lot was 8 or 9 inches. The snow on the road was NOT freshly plowed and it was drifting. I was going at a safe speed for the condition on the road. The car has the tires it came with and I'm happy with their performance in the snow. I've got a drive shaft carrier bearing going out and when it gets replaced I'd like to look at the setup under the car to see what's there. The mech working on it doesn't seem to think it's a HALDEX unit.

 

I've driven nothing but RWD cars and several rental FWD cars. The RWD cars either had an open differential or a limited slip/posi. The open diff would always kick out to the right no matter what (the rear of the car tended to swerve to the right) when torque was transmitted to that 1 wheel on snow or ice. With the posi, the rear would tend to swing to either the left or the right depending on the conditions but it seems that it would swing to the left more often.

 

I've been trying to dig up tech data on the CD3 AWD system but haven't been able to get anything more than press releases. If it is remotely similar to a Haldex, the rear differential might be an electronically controlled viscous coupling unit. The cool thing about the Subaru is that the front, center, and rear differentials all have limited slip differentials so they're working full time.

[Jimmy G]

I've driven nothing but RWD cars and several rental FWD cars. The RWD cars either had an open differential or a limited slip/posi. The open diff would always kick out to the right no matter what (the rear of the car tended to swerve to the right) when torque was transmitted to that 1 wheel on snow or ice. With the posi, the rear would tend to swing to either the left or the right depending on the conditions but it seems that it would swing to the left more often.

 

I've been trying to dig up tech data on the CD3 AWD system but haven't been able to get anything more than press releases. If it is remotely similar to a Haldex, the rear differential might be an electronically controlled viscous coupling unit. The cool thing about the Subaru is that the front, center, and rear differentials all have limited slip differentials so they're working full time.

 

I'll see what I can find out when they fix my drive shaft. My wife had a 500 AWD for a two year lease and she liked it in the snow. I'm a Ford retiree so I won't be driving a Subaru any time soon. :D

[metroplex]

I'll see what I can find out when they fix my drive shaft. My wife had a 500 AWD for a two year lease and she liked it in the snow. I'm a Ford retiree so I won't be driving a Subaru any time soon. :D

 

The X-Plan is mainly the reason why I am considering a Ford. Although I can still get the VIP discount for any new Subaru (their equivalent to the X-Plan), but the Ford Z-Plan is an even better deal

[Jimmy G]

The X-Plan is mainly the reason why I am considering a Ford. Although I can still get the VIP discount for any new Subaru (their equivalent to the X-Plan), but the Ford Z-Plan is an even better deal

 

I hope you'll consider buying a Ford. The choice is up to you, but I'm a little biased. :beerchug:

[metroplex]

I forgot to ask - does the AWD Fusion exhibit lift-off oversteer or any torque steer?

[Jimmy G]

I forgot to ask - does the AWD Fusion exhibit lift-off oversteer or any torque steer?

 

None that I can feel. My SHO had gobs of torque steer! Sometimes it would jump all over the place.

The rear stays firmly planted when I get off the gas.

[metroplex]

None that I can feel. My SHO had gobs of torque steer! Sometimes it would jump all over the place.

The rear stays firmly planted when I get off the gas.

 

I'd love to see what kind of differential they used in the front transaxle on the Fusion. It *seems* like it has some type of limited slip if people are reporting extremely balanced behavior in the snow. The fact you could run donuts in the parking lot suggests the rear does get plenty of power. I don't recall any of the car magazines doing any extensive testing to compare the various AWD systems. That would be an interesting read for sure.

[Jimmy G]

I'd love to see what kind of differential they used in the front transaxle on the Fusion. It *seems* like it has some type of limited slip if people are reporting extremely balanced behavior in the snow. The fact you could run donuts in the parking lot suggests the rear does get plenty of power. I don't recall any of the car magazines doing any extensive testing to compare the various AWD systems. That would be an interesting read for sure.

 

When mine goes into the shop, I'm going to ask the Ford mechanic about the system. Maybe he'll explain it if he has the time.

It is a good car for the snow. I prefer driving it over my F150. The truck has more ground clearance but wanders around on acceleration in the snow.

We're getting a TON of snow right now. I can't see the end of my lane and when that happens, I don't go out.

[akirby]

Why are you bringing this up again? Didn't we already discuss it to death 3 weeks ago?

[Jimmy G]

Why are you bringing this up again? Didn't we already discuss it to death 3 weeks ago?

 

If he buys a Ford product because of this discussion it will have been worth it. Why do you care?

[akirby]

If he buys a Ford product because of this discussion it will have been worth it. Why do you care?

 

I was just curious why someone would ask a question and receive several answers in great detail, then turn around and ask the same question 3 weeks later. The answer hasn't changed in 3 weeks.

[metroplex]

I was just curious why someone would ask a question and receive several answers in great detail, then turn around and ask the same question 3 weeks later. The answer hasn't changed in 3 weeks.

 

I never did find a conclusive answer to my original question. Speculation isn't the same as a definitive answer. Based on my research on the 2007 500 AWD, it appears the rear differential would be an electronically actuated limited slip differential since it is a Haldex unit. The LSC would transmit power to the active coupling unit and that module would clamp the clutches in the rear differential as needed, transmitting power to both or one of the rear half-shafts.

 

The question is, has anyone determined if the CD3 AWD system is based on or similar to the Haldex unit, and if the front differential in the transaxle is indeed open, or if it is a Torsen-style limited slip? The 500 AWD's FSM entries did not contain anything that would indicate the differential in the transaxle was limited slip or open.

[akirby]

I never did find a conclusive answer to my original question. Speculation isn't the same as a definitive answer. Based on my research on the 2007 500 AWD, it appears the rear differential would be an electronically actuated limited slip differential since it is a Haldex unit. The LSC would transmit power to the active coupling unit and that module would clamp the clutches in the rear differential as needed, transmitting power to both or one of the rear half-shafts.

 

The question is, has anyone determined if the CD3 AWD system is based on or similar to the Haldex unit, and if the front differential in the transaxle is indeed open, or if it is a Torsen-style limited slip? The 500 AWD's FSM entries did not contain anything that would indicate the differential in the transaxle was limited slip or open.

 

The eLSD rear differential is only in the 4th gen. Haldex system which Ford is not using.

 

Ford's in-house AWD uses an electronically controlled center differential to send power to the rear when needed (as opposed to the original Haldex mechanical unit that only transfers torque when slip occurs). I can't find any mention of limited slip on the front or rear differentials on the Fusion so I think it's safe to assume that it doesn't have one - otherwise it would be touted as a feature just like the Subarus.

 

I'll ask a Ford engineer to see if they can confirm that.

[metroplex]

The eLSD rear differential is only in the 4th gen. Haldex system which Ford is not using.

 

Ford's in-house AWD uses an electronically controlled center differential to send power to the rear when needed (as opposed to the original Haldex mechanical unit that only transfers torque when slip occurs). I can't find any mention of limited slip on the front or rear differentials on the Fusion so I think it's safe to assume that it doesn't have one - otherwise it would be touted as a feature just like the Subarus.

 

I'll ask a Ford engineer to see if they can confirm that.

 

Thanks akirby. I am looking at the 2007 500 AWD FSM and it shows that there is an electronic active coupling unit for the rear differential:

 

The axle assembly, is driven by the engine through the transaxle to the power transfer unit (PTU) through the driveshaft to the active on-demand coupling. The differential electronic module (DEM) on the active on-demand coupling regulates how much torque is applied to the axle assembly and halfshafts. The DEM monitors front wheel speed and rear wheel speed to determine how much torque (up to 1,000 Nm at the coupling) to apply to the rear wheels. The DEM uses oil pressure via an oil pump and a solenoid to regulate torque through the active on-demand coupling.

 

The axle assembly uses 2 types of lubricant. In the rear of the axle assembly it uses SAE 80W-90 Premium Rear Axle Lubricant XY-80W90-QL. In the front of the axle assembly it uses Volvo Transmission Oil 116-1641.

 

The axle assembly consists of the following components:

 

Differential electronic module (DEM)

Active on-demand coupling

Rear axle housing

Rear halfshaft (RH)

Rear halfshaft (LH)

 

One of the diagrams showed "HALDEX" on a fluid pan, but this is on the 500 (before it was called Taurus). I understand this is not the same unit on the CD3 cars.

[akirby]

Ford engineer confirms the CD3s have open diffs. He said they have a test site with rollers on one side and if you hit the gas the wheels spin on the rollers and it goes nowhere.

 

I'll ask about the Taurus system. From the description above it sounds like there is no center diff, but rather the rear diff that controls the front/rear torque split. I believe that's the "center coupling" they're talking about but I could be wrong. I don't think there is a separate center diff and rear diff in that setup. I also don't know if that's the same setup used in the Taurus and MKS.

[metroplex]

Ford engineer confirms the CD3s have open diffs. He said they have a test site with rollers on one side and if you hit the gas the wheels spin on the rollers and it goes nowhere.

 

I'll ask about the Taurus system. From the description above it sounds like there is no center diff, but rather the rear diff that controls the front/rear torque split. I believe that's the "center coupling" they're talking about but I could be wrong. I don't think there is a separate center diff and rear diff in that setup. I also don't know if that's the same setup used in the Taurus and MKS.

 

Thanks for the clarification.

 

The 500 AWD doesn't have a center diff, but instead a PTU (Power take-off unit) is mounted behind the transaxle, which leads to a driveshaft connected to an active coupling unit for the rear diff (viscous coupling). This is from the FSM description for the 500 AWD so I am unsure if they changed it for the 2008 Taurus.

[awdpath]

Thanks akirby. I am looking at the 2007 500 AWD FSM and it shows that there is an electronic active coupling unit for the rear differential:

 

 

 

One of the diagrams showed "HALDEX" on a fluid pan, but this is on the 500 (before it was called Taurus). I understand this is not the same unit on the CD3 cars.

 

 

"The main role of the active on-demand coupling and the differential electronic module (DEM) is to regulate the all wheel drive (AWD) function by distributing torque between the front and rear axles." [ No side to side power transfer ]

 

http://f150online.com/forums/showthread.php?t=317410

[awdpath]

I never did find a conclusive answer to my original question. Speculation isn't the same as a definitive answer. Based on my research on the 2007 500 AWD, it appears the rear differential would be an electronically actuated limited slip differential since it is a Haldex unit. The LSC would transmit power to the active coupling unit and that module would clamp the clutches in the rear differential as needed, transmitting power to both or one of the rear half-shafts.

 

The question is, has anyone determined if the CD3 AWD system is based on or similar to the Haldex unit, and if the front differential in the transaxle is indeed open, or if it is a Torsen-style limited slip? The 500 AWD's FSM entries did not contain anything that would indicate the differential in the transaxle was limited slip or open.

 

To clarify, if "eLSD" is referred to the Haldex 4.0 ( Saab xwd 2008) , then yes, it does have LSD with electronic control within the axle using "wet, multi-plate clutch units from Haldex". Here lies the confusion, I suggested that the Fusion AWD system function like "eLSD" without realizing that the Haldex 4.0 ( Saab xwd 2008) actually has mechanical components that qualifies as "true" LSD although electronically controlled within the axle. Akirby described the Fusion AWD side to side power transfer system as "Open diffs with traction control", while others on the net called it "ediff", "ELD","eLSD", "E-LSD",sucks,junk..etc. Here is one from Porsche:

 

"PSM also assists when you’re accelerating on a slippery surface, applying the integrated Automatic Brake Differential (ABD) and Anti- Slip Regulation (ASR) functions to help maintain traction and stability."

 

 

RWD open/standard differentials with Traction/ABS programed for side to side power transfer at work:

 

http://www.1addicts.com/forums/showthread.php?t=4483

 

Note that the reviewer said the BMW 135i has LSD. Did he mean "true" LSD? Was it modified? Stock BMW 135i does not come with "true" LSD.

 

 

 

At 39s in, notice inner rear wheel braking

 

 

http://www.bmwblog.com/2007/12/04/bmw-135i-drifting/

 

Again, inner rear wheel braking because of less traction which has an effect of transferring power to the outer rear wheel where there is more weight/traction resulting in oversteer. By applying steady throttle and counter steer, the car drifts.

[metroplex]

"The main role of the active on-demand coupling and the differential electronic module (DEM) is to regulate the all wheel drive (AWD) function by distributing torque between the front and rear axles." [ No side to side power transfer ]

 

http://f150online.com/forums/showthread.php?t=317410

 

That might be true for the F-150, but the 500 appears to regulate that ability to the PTU at the rear of the transaxle. The active coupling unit is strictly for the rear differential.

 

Regarding the BMW 1-series, that's rather interesting but it isn't difficult to get the rear end to swing loose with an open differential. Drifting is fun but I am more interested in take-off traction in deep snow and slush, and at-speed dynamics in snow and slush (50+ mph). It seems that having all open differentials on the CD3 is an engineering oversight or a cost cutting measure. Depending on the ABS/traction control for "limited slip-like" capabilities isn't very good because if the brakes overheat, you're going to end up with an open differential (1 wheel drive).

[akirby]

Thanks for the clarification.

 

The 500 AWD doesn't have a center diff, but instead a PTU (Power take-off unit) is mounted behind the transaxle, which leads to a driveshaft connected to an active coupling unit for the rear diff (viscous coupling). This is from the FSM description for the 500 AWD so I am unsure if they changed it for the 2008 Taurus.

 

I just confirmed that the Taurus/Montego/Taurus X/MKS system is identical to the CD3s now. Open diffs all around.

 

The 500 system was a Haldex unit although it was the older (I assume) 3rd gen system, not the 4th gen that regulates torque side to side.

[metroplex]

I just confirmed that the Taurus/Montego/Taurus X/MKS system is identical to the CD3s now. Open diffs all around.

 

The 500 system was a Haldex unit although it was the older (I assume) 3rd gen system, not the 4th gen that regulates torque side to side.

 

Thanks akirby. I too confirmed that even the Edge has open differentials all around.

 

The only Subaru that has limited slip differentials in the front, center, AND rear is the WRX STI. The others all have open front differentials and the WRX / Legacy GT / GT-Spec B has limited slip rear differentials. The Charger R/T AWD actually has open diffs all around according to Edmunds.