metroplex

I forgot if the Fusion AWD uses a viscous coupling or mechanical LSD center diff? I hear the viscous coupling units can burn out and cost a pretty penny to replace. I'm kind of skeptical about the Ford AWD systems because I've been tricked by Ford in the past with its Traction Control and open differentials. I'd love to learn more but Ford is kind of hush hush about its system, and there aren't many videos on YouTube of people racing their AWD CD3 cars.

Yep, open diffs in the front and rear

I just learned that the Fusion IKT will work on 2008 Mustangs but I also read that it is incompatible with 2005-2006 Mustangs. Does anyone know if the IKT will work on 2007 Mustangs? Ford's accessory catalog shows the same part # for the keyless entry pad on the 07-08 Stang and 07-08 Fusion (this is the pad that you stick on the outside of the car).

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.

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).

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.

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.

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.

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.

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

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'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.

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?

Will they ever offer a 300 hp AWD Fusion with a manual transmission and HID headlamps?

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?