325iX AWD question

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Dave Plowman (News) wrote:


Do you know the Year when Rover first started using the center differential in their trucks? Here in the states I know that New Process was making a full time 4wd transfer case for GM and Dodge trucks in the early 70s. These trucks are easy to spot and tell apart from other 4wd trucks of that era by their lack of any front lock out hubs. But I agree Rover was probably first, I just don't know for sure since those old Landies very scarce here in Ohio. (I think I've only ever seen one on the road)
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June 1970 saw the introduction of the Range Rover - although it was a very different vehicle from today. It was designed as a working 4x4 which would also offer some comfort - in those days Land Rovers etc were pretty basic. But the Range Rover still had rubber floor covering and plastic seats so it could be hosed out after a day working on the farm.

The Range Rover kept the same basic body for over 20 years - although the original was two door only. And the drivetrain up until a couple of years ago when the old Buick derived V-8 was replaced with a Ford one. The Land Rover (Defender) can trace its roots back to the '40s, when it was an interpretation of the WW2 Jeep.
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Yeah, the center diff makes all the "difference" two rovers, which are both full time 4 wheel drive. Not all wheel. But I can also lock that center diff and force the 50/50 power split. What is a good breaking point definition of AWD, vs. 4WD?
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Corey Shuman wrote:

Full time 4WD = AWD.
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no, this is actually not true. Full time four wheel drive does not neccessarily transfer torque to non-spinning wheels, where as AWD does. AWD has traditionaly used viscous couplers to accomplish this but electronic systems are now being used as well. When I posted originally I was looking for what exactly was used in the E30 IX's, and thanks to all who replied. Very much appreciated.

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We've now got several versions of what comprises AWD over 4WD.
Any more? ;-)
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Matthew Warren wrote:

No, *that* is not true. AWD does *not* neccesarily transfer torque to the non-spinning wheels.
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so if awd means full time 4wd, then why does the freelander get stuck in mud and cant traverse rocks when the "4wd" Disco, has no problem with the same obstacles??
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The Freelander hasn't got a low ratio gearbox?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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No low range on the Freelander. Just AWD...
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Corey Shuman wrote:

Because "full time" is NOT superior for off-road traction. It just means "always on" so you get to use it in all road conditions. True 4WD *is* superior in off-road conditions because the transfer case sends power (equally) to both front and rear axles. So you will get power from either axle with traction regardless of what the other axle is doing. However, since the transfer case has no "differential" mechanism, the front and rear axles can't turn at different speeds, which means you can't engage it on dry roads if you intend on turning.
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Ah.. and there lies the superiority of the Rover, (or at least the older ones) a center diff that does allow the front and rear axles to turn at different speeds- or if you are feeling fancy, you can lock the center diff and force equal power., However, this goes back to the beginning of the article and the point I was trying to discern...
from John Burns "Find that hard to believe. The system has a chain driven transfer case at the back of the gearbox. It's permanent 4wd, nothing fancy. "
and "Full time 4WD = AWD. "
So it would seem to be a concensus that 4wd=awd, yet the awd still does not have the off road ability of a 4wd, so all Im asking is that the two terms not be used interchangabley. :)
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So, Fred, my '01 330xi is a superior 4WD system for off-road use, since it has a permanent 33% front 67% rear torque split. I think you need a better defining condition for AWD vs. 4WD.
FloydR
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Floyd Rogers wrote:

Read my post again. I said that AWD (aka full time 4WD) is *not* superior. Therefore (as if you didn't already know) your 330xi is not an off road monster, but is more suitable to use on-road.
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Sorry, Fred, but you *agree* (with Corey) that a permanent split defines 4WD, yet you say that the 330xi is AWD. To me, those statements are incompatible. In fact, the 330xi (using ADB) can move when only one wheel has traction, which is superior to your 4WD explanation.
It's all semantics anyway; what matters is if the system gets you where you want to go. My 330xi gets me up snowy roads and our gravel roads quite well. My Toyota T100 4x4 gets me up most forest roads that need more ground clearance and lower speeds that my 330xi doesn't.
FloydR
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all-wheel drive: (AWD) A variation of four-wheel drive (4WD) designed to improve on-road traction in unfavorable road conditions or for ultra high performance driving. All-Wheel Drive (AWD) reduces wheel slippage and provides greater driver control over the vehicle. AWD usually does not require the driver to actively engage the system and does not have a low range. AWD automatically splits engine torque between the front and rear wheels as needed. All-Wheel Drive is generally an on-road system and is not designed for off-road use.
four-wheel drive: (4WD) A type of drive system in which both front wheels are connected to its own differential and axles, and both back wheels are connected to its own differential and axles. Between these two differentials there is a transfer case which allows you, in the case of part-time four wheel drive, to switch between two-wheel drive and four-wheel drive. In full-time four-wheel drive power is sent to both differentials.
full-time four-wheel drive: A condition where all four wheels are always being driven by the drivetrain. It may include the option of part-time (that is, shifting into 2WD for dry pavement) operation, and may or may not have Hi and Lo 4WD speed ranges. The British term is "permanent four-wheel drive."
real-time four-wheel drive: An automatic four-wheel drive engagement by means of an electro-hydraulic clutch or a viscous coupling incorporated in the drivetrain.
Ferguson four-wheel drive: A transmission system in which power is distributed through a special viscous coupling differential, 37% to the front wheels and 63% to the rear wheels
Torsen four-wheel drive: Based on the principle that a worm gear can drive a roller but not vice versa, the Torsen differential balances different wheel speeds due to different travel distances, whereas speed differences due to differing adherence situations are not balanced. A permanently engaged four-wheel drive incorporating a torsen differential
automatic four-wheel drive: (A4WD) A driving system that automatically engages 4WD as needed, usually by monitoring differences in individual wheel speeds and thus sensing when a tire is slipping.
part-time four-wheel drive: A manually selectable four-wheel drive
Cripes!!!!
wrote

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Indeed! And you haven't even brought up locking diffs! Or auto-locking hubs and all the other plethora.
FloydR
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