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Discussion Starter · #1 ·
I tried this over in the Terrain section, but nothing forthcoming.
Perhaps there are some Mechanical Engineers here.

Can anyone point me to a mechanical schematic drawing/description of the Terrain AWD system?

Curious as to how it all works.
The physical components involved, the layout, [transverse engine?], power take offs, diffs & relative power % feed front/rear? - does it vary??.
& so on.

LW4T
 

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Longwait4Train said:
I tried this over in the Terrain section, but nothing forthcoming.
Perhaps there are some Mechanical Engineers here.

Can anyone point me to a mechanical schematic drawing/description of the Terrain AWD system?

Curious as to how it all works.
The physical components involved, the layout, [transverse engine?], power take offs, diffs & relative power % feed front/rear? - does it vary??.
& so on.

LW4T

I tried finding out this information as well and decided to contact GM. Their reply was pretty basic:


"Based on our research the AWD system on Equinox is an intelligent system designed to offer exceptional performance under a wide variety of operating conditions.

The AWD system operation is most correctly described as a full time, electronically controlled, intelligent AWD system. The coupling controller constantly monitors road conditions and driver inputs to command the fast acting clutch to send the appropriate amount of torque to the rear wheels. This results in optimal traction and vehicle handling for all speeds and surface conditions.

The AWD system proactively sends torque to the rear wheels during acceleration, minimizing the chance of wheel slip. In demanding conditions, such as when the front wheels are on snow or ice, the AWD controller commands additional torque to the rear axle to result in a smooth, seamless launch, even on slippery surfaces."
 

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its a multi plate clutch coupling system....

functions like 2WD when multi-plate clutch coupling is not engaged, and like 4WD highrange in a part time 4WD system when the clutch is engaged (usually by computer although some allow manual control). Some vehicles in this category have varying degrees of control in the torque distribution between front and rear via allowing some of the clutches in a multi- plate clutch coupling to engage and slip varying amounts.
 

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Discussion Starter · #4 ·
gar187er said:
its a multi plate clutch coupling system....

functions like 2WD when multi-plate clutch coupling is not engaged, and like 4WD highrange in a part time 4WD system when the clutch is engaged (usually by computer although some allow manual control). Some vehicles in this category have varying degrees of control in the torque distribution between front and rear via allowing some of the clutches in a multi- plate clutch coupling to engage and slip varying amounts.
I vaguely get it.

Re the Equinox/Terrain AWD, [excuse basic queries, I haven't looked over 1 of these yet ]

Is the motor Transverse mounted?

Also runs a drive-shaft to rear wheels?

'Normal' AWD: what % of drive is going through front & what through rear wheels? {I think I read 60/40 F/Rear, or 40/60 somewhere, not sure which way around it was}

Thanks
LW4T
 

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transverse...

and yes there is a shaft to the rear....

normal for us? 100/0 it only kicks in when the front starts to slip...
 

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Discussion Starter · #6 ·
gar187er said:
transverse...

and yes there is a shaft to the rear....

normal for us? 100/0 it only kicks in when the front starts to slip...
Well, that is interesting: 100/0

An FWD with ability to add RWD as needed.

I had assumed it was full time AWD & I imagine a lot of Equinox/Terrain buyers may have assumed the same.

Can the driver bring in the RWD manually if feel need for it??

Also has implications for tire wear, with the fronts wearing quicker/ need to rotate.

Thanks
LW4T
 

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many vehicles are like this, unless it states fulltime 4wd....thats why you do not see a dip in fuel economy (1mpg difference) when comparing the fwd vs awd

i dont believe there is a switch for it...havent been in the new models....but everything is essentially computer controlled....no reason for awd if the front wheels arent slipping? right?

this really doesnt impact tire wear that much....driving style, and weight distibution impact tire wear more then this.....you should rotate your tires regularly regardless of what kind of drivetrain the vehicle has....

read up if ya feel like it.....
http://en.wikipedia.org/wiki/Four-wheel_drive#4WD_versus_AWD
 

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I thought the Nox/Rain took a 10% hit in fuel economy for having AWD - at least per EPA. Not sure about real-world.
 

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I'm 1.1 L/100km (2.4 US MPG) better fuel economy at 3,400 km with FWD than I was getting with AWD at 12,000km so there is some difference. Same vehicle otherwise.

The FWD is about 150 pounds lighter, and there must be a little less drag not having a driveshaft or rear differential.
 

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My understanding from a salesperson and a service technician is that the AWD is 10% to the rear wheels all the time unless more is required due to slippage.
 

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My understanding is also that in the AWD setup, it uses about 90% of the front, unless there's a loss of traction. It's not a full time 50/50 setup, or something a little more advanced.
 

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AWD as applied to different makes can mean different things. For example, in the Audi Quattros in use by my family, the Quattro AWD is active all the time with nearly 50%/50% power distribution F/R and is aimed at overall performance handling in dry as well as wet/snow conditions. In the Nox/Terrain application, the AWD is always there but its intent is solely for traction improvement and works in conjunction with traction control. In the Nox/Terrain, power is applied nearly "100%" to the front unless wheel slippage is detected whereby traction control is engaged and power is also transferred automatically to the rear via computer control using an algorithm particular to the vehicle. In the Nox/Terrain it is NOT user-controlled and is designed to be seamless to the driver; the driver throttles up and if it's slippery the rears get more and more power to get the vehicle going. The system is designed for on-road traction in the case of the Nox/Terrain. The fuel economy reduction is due to the extra weight combined with parasitic losses added by the AWD drivetrain (the driveshaft to the rear and the differential in the rear).

As an aside, the V6 gives much less fuel economy than the I4 on the highway more due to the parasitic frictional losses from the extra 2 cylinders and different, heavier-duty transmission than to the extra weight or arguable engine design issue. The difference is less dramatic in the city cycle. At 60mph, a V6 Nox/Terrain needs the same horsepower to maintain speed as does an I4, all else being equal. So, at 60mph (flat level ground) the fuel economy hit from having the V6 over the I4 is due mostly to the extra friction from the 50% increase in moving engine internals (4cyl + 50% = 6cy) and the heavier-duty transmission internals. Adding AWD to both also adds parasitic frictional forces that reduce economy.

I have been waiting for some unclassified schematics to come out of GM's Tech Center regarding the AWD system and when they are OK for release I'll post what they give me; I have some friends in engineering on the inside there and they are very good about confidentiality so I have to respect that. Hope the info I gave helps a bit.
 

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I would like to know if my 2011 NOX AWD is FWD biased until the front wheels slip, does it then transfer torque to the rear? These types of AWD systems are better on fuel consumption as they remain in FWD until needed. Is this what we have. i emailed Customer Support, and they just told me to check their website, and my owners manual. None of which describe what type of system we have.
 

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yes, thats why the mpg is only 1 mpg different....

also thats why its awd, and not 4wd...4wd is mostly used as a full time designation....
 

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IIRC the SRX uses the Haldex AWD system which is different and superior to the system used in the Terrain/Equinox.
 
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