How does Pacifica's AWD *exactly* work? - Chrysler Forum - Chrysler Enthusiast Forums

Chrysler Pacifica Luxury meets versatility in this mid-sized sport utility vehicle

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Old 09-16-2013, 03:35 PM
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Question How does Pacifica's AWD *exactly* work?

So I'm thinking about getting a Pacifica, pre-facelift (04 or 06).

I'm from Europe (there are a few Pacificas imported here, legally) and I live in the mountains (or on the verge of the local range), already behind the "salt line" where no road salt is used in winter (thank God!) and where we drive as mother nature meant it... So far with a heavy-nose-FWD car but that's what I'm planning to change.

Although it's an unshakeable fact that there are far more superior AWD systems out there (and yes, I'm also eyeing a 2007 Outback...), Pacifica somehow intrigues me by it's unique not-just-allroad-but-not-SUV style... It seems comfortable, huge and safe for a family. And so before I write it off completely for not having an AWD system worth thinking about, I'd like to know what exactly I can expect from it.

The thing is that I seem to be finding various opinions on what exactly the first gen Pac has. So - it has a 100% mechanical viscous-coupling-based AWD, right?

The biggest question: how much torque do the rear wheels get in normal conditions and HOW FAST do they get more torque in case they need it?

My understanding is that the VC clutch has to warm up first to actually start transmitting torque. Does it mean I'll be sitting in snow, spinning my front wheels for a few (tens of?) seconds, waiting for the fluid to thicken and take the rear wheels to the party? How fast this is? And much more importantly - can I count on the AWD system to kick in on the road when I get into a critical situation and things happen in matter of (milli)seconds...? Or is this out of the question? I mean like when I lose traction in a bend/curve, car starts to slip, I need to correct it, do something... will I get AWD? Or will I have "bought Pacifica instead of Subaru" on my tombstone?

I've went over several YouTube videos and it seemed to me that the rear wheels engage almost immediately in the snow / on ice... was it just because people had the VC warmed up already? Or is it really that fast? Or is it just not true that Pacifica puts 100% torque on front wheels by default?

Also please take into consideration that winter tires are a no-brainer for me... Never had anything else in winter and never would.
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Old 09-17-2013, 03:07 PM
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Nobody? Come on, guys... you actually own these cars. You must at least have some personal experience, right?
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Old 09-17-2013, 11:48 PM
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I am reading this forum for few years but I do not remember ever reading a good explanation of how does AWD system work in Pacifica. In fact in other crossovers like Pilot, Santa Fe or Highlander, such information (read accurate) is hard to come by as well.

No one says under what conditions does AWD system engages & at what speed it disengages. Also I have not seen a description of a dedicated selector or lever to engage AWD system.
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Old 10-02-2013, 03:53 PM
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AWD has a viscous coupling design with no buttons to press or levers to pull

Automatically transfers power front front wheels to the rear wheels when front wheels begin to slip.

This provides increased stability and steering control in inclement weather or slippery terrain.

AWD transfers engine power to all four wheels, AWD delivers the pulling power of FWD and the pushing power of RWD for superior traction, control, acceleration, and cornering.

The heart of the system is a viscous coupling torque-transferring device (its the drive link between the front and rear axles. During normal operation, most of the torque is directed to the main driving wheels. When main driving wheels start to slip, the viscous coupling sends more torque to the secondary driving wheels, according to the magnitude of the slippage. This is done automatically, with no driver input. There is constant torque flow to the front and rear axles.

The rear driveline module assembly con-sists of three main components:
� Bi-Directional Overrunning Clutch (BOC)
� Viscous Coupling
� Differential Assembly

The viscous coupling and bi-directional overrun-ning clutch are contained within an overrunning clutch housing, which fastens to the differential assembly. The overrunning clutch housing and differ-ential assembly have unique fluid sumps, each requiring their own type and capacity of fluid. The overrunning clutch housing requires Mopar ATF+4.
The differential assembly requires Mopart 75W-90 Gear and Axle Lubricant.

Driveline module service is limited to the following components:
� Differential Assembly (serviced only as assem-bly)
� Viscous Coupling
� Bi-Directional Overrunning Clutch (BOC)
� Overrunning Clutch Housing
� Seals (Input Shaft, Output Shaft, Overrunning Clutch Housing O-rings)
� Input Flange/Shield
� Vents
� Fasteners

The primary benefits of All Wheel Drive are:
� Superior straight line acceleration, and cornering on all surfaces
� Better traction and handling under adverse conditions,resulting in improved hill climbing ability and safer driving.

The heart of the system is an inter-axle viscous coupling. The vehicle retains predominantly front-wheel drive characteristics, but the All Wheel Drive capability takes effect when the front wheels start to slip. Under normal level road, straight line driving, 100% of the torque is allocated to the front wheels.

The viscous coupling controls and distributes torque/ power to the rear wheels. The viscous coupling transmits torque to the rear wheels in proportion of the amount of the slippage at the front wheels. This variable torque distribution is automatic with no driver inputs required. The coupling is similar to a multi-plate clutch. It consists of a series of closely spaced discs, which are alternately connected to the front and rear drive units. The unit is totally sealed and partially filled with silicone fluid. There is no adjust-ment, maintenance or fluid checks required during the life of the unit.

The overrunning clutch allows the rear wheels to overrun the front wheels during a rapid front wheel lock braking maneuver. The overrunning action pre-vents any feed-back of front wheel braking torque to the rear wheels. It also allows the braking system to control the braking behavior as a two wheel drive (2WD) vehicle.

The overrunning clutch housing has a separate oil sump and is filled independently from the differen-tial.

The fill plug is located on the side of the over-running clutch case. When filling the overrunning clutch with lubricant use Mopart ATF+4.

The differential assembly contains a conventional open differential with hypoid ring gear and pinion gear set. The hypoid gears are lubricated by SAE 75W-90 Mopart Gear and Axle Lubricant.
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Old 01-07-2014, 07:27 PM
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When I raised my 2006 chrysler pacifica on a lift and pressed the gas, all four tires spin evenly and freely. During a small snow storm, I got stuck and only the front tires were turning. I am wondering what could be wrong with my AWD system. The main shaft, as I mentioned before, was turning together with the front wheel, but the rear wheels were dead on the icy surface.
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