R

RobertS975

Guest
Looking at various Yukon XL/ Denali models. Is there an advantage to 4WD vs AWD
vehicles? My 97 GMC Suburban will go through deep snow if needed. Will a newer
AWD vehicle or a 4WD "when needed" vehicle perform as well? Advice needed!
 
RobertS975 wrote:
>
> Looking at various Yukon XL/ Denali models. Is there an advantage to 4WD vs AWD
> vehicles? My 97 GMC Suburban will go through deep snow if needed. Will a newer
> AWD vehicle or a 4WD "when needed" vehicle perform as well? Advice needed!

Two major differences exist between the two, (part-time) 4WD usually implies a transfer case, which is typically locked (gear or chain driven) and a lower gear range. If the AWD system has an option to lock the center diff, then you would have the same
traction options as 4WD. If you find you need low range to get through deep snow (I find low range is a benefit when I get in deep snow), then as long as the AWD system has a low range, then that would also be comparable. Of course there will be
variations, like a limited slip type center diff in AWD.

--
Roger
 
On 19 Jan 2004 21:43:21 GMT, roberts975@aol.com (RobertS975) wrote:

>Will a newer
>AWD vehicle or a 4WD "when needed" vehicle perform as well? Advice needed!

Any system of AWD/4wd that can be used on pavement WILL NOT perform as
well off-road or in real severe conditions. BUT, the vehicle you
mentioned also has true four wheel drive capability, (as well as the
AWD setting), as it includes 4 high lock/4 low lock in the T-case.

(I own an AWD Safari van and I can tell you that while its AWD system
isn't as good as true 4wd, it is about 90% capable. Would be 95% if
it offered low range. Not every AWD system is as good as this one
though.)

Matt
99 V-10 Super Duty, Super Cab 4x4
96 GMC Safari AWD Hi-Top Conversion
 
>
> Any system of AWD/4wd that can be used on pavement WILL NOT perform as
> well off-road or in real severe conditions.

Why?

--
Julian
---------
= Pretentious Sig required =


 
In article <jBePb.62850$Es.47266@news-lhr.blueyonder.co.uk>,
exit@nomore.com says...
> >
> > Any system of AWD/4wd that can be used on pavement WILL NOT perform as
> > well off-road or in real severe conditions.
>
> Why?
>
>
Since the front and rear axle are not binded together by a solid
mechanical linkage in most AWD systems you could end up in a situation
where all or some of your power is going to only the front or rear drive
wheels.
--
____________________
Remove "X" from email address to reply.
 
Let's not forget that in most stock 2WD/4WD vehicles (such as a 1984
chevy pickup) the center diff. locks the front and rear drive shafts
together but there are two more diffs, front and rear, and under most
conditions these differentials only transmit power to either the left
or right wheels. "Peg Leggers" in the drag racing world. In certain
circumstances (when you are traveling perfectly straight with equal
traction on both wheels) you can get the dif to lock up. So even if
you have a 4X4 it doesn't mean you get power to 4 wheels.

Today's AWD systems sometimes sense wheel spin and dynamically brake
the wheels to transfer power "from the wheels that slip to the wheels
that grip". Its a form of anti-lock brakes for accelerating. In
effect you do get power to all 4 wheels.

Josh
 
Chris Phillipo wrote:
> In article <jBePb.62850$Es.47266@news-lhr.blueyonder.co.uk>,
> exit@nomore.com says...
>>>
>>> Any system of AWD/4wd that can be used on pavement WILL NOT perform
>>> as well off-road or in real severe conditions.
>>
>> Why?
>>
>>
> Since the front and rear axle are not binded together by a solid
> mechanical linkage in most AWD systems you could end up in a situation
> where all or some of your power is going to only the front or rear
> drive wheels.

Possibly correct, but Matt says it is impossible for a 4WD system that can
be used on-road to perform as well off-road as a part-time system which is
wrong.

My full-time 4WD works very well on-road and has a solid mechanical diff
that locks the front and rear axles together completely making it identical
to a part-time 4WD system when off-road.

--
Julian
---------
= Pretentious Sig required =


 
On Wed, 21 Jan 2004 11:32:49 GMT, "Exit" <exit@nomore.com> wrote:

>My full-time 4WD works very well on-road and has a solid mechanical diff
>that locks the front and rear axles together completely making it identical
>to a part-time 4WD system when off-road.
>
>--
>Julian

Sorry, I thought I made the point that an AWD or 4WD system is only as
capable off-road if it has a way to lock the transfer case. (In fact,
the GM product mentioned has such a thing.......)

Well, it looks like at least Chris got my point....

Matt
99 V-10 Super Duty, Super Cab 4x4
 
Matt Mead wrote:
> On Wed, 21 Jan 2004 11:32:49 GMT, "Exit" <exit@nomore.com> wrote:
>
>> My full-time 4WD works very well on-road and has a solid mechanical
>> diff that locks the front and rear axles together completely making
>> it identical to a part-time 4WD system when off-road.
>>
>> --
>> Julian
>
> Sorry, I thought I made the point that an AWD or 4WD system is only as
> capable off-road if it has a way to lock the transfer case. (In fact,
> the GM product mentioned has such a thing.......)
>
That may have been your point, but this is what you typed:

'Any system of AWD/4wd that can be used on pavement WILL NOT perform as
well off-road or in real severe conditions'

--
Julian
---------
= Pretentious Sig required =


 
On Wed, 21 Jan 2004 16:57:59 GMT, "Exit" <exit@nomore.com> wrote:

>That may have been your point, but this is what you typed:
>
>'Any system of AWD/4wd that can be used on pavement WILL NOT perform as
>well off-road or in real severe conditions'
>
>--
>Julian
>---------

Of course you are right Julian. My apologies......

Matt
99 V-10 Super Duty, Super Cab 4x4
 
In article <rcyPb.69938$Es.27959@news-lhr.blueyonder.co.uk>,
exit@nomore.com says...
> Matt Mead wrote:
> > On Wed, 21 Jan 2004 11:32:49 GMT, "Exit" <exit@nomore.com> wrote:
> >
> >> My full-time 4WD works very well on-road and has a solid mechanical
> >> diff that locks the front and rear axles together completely making
> >> it identical to a part-time 4WD system when off-road.
> >>
> >> --
> >> Julian
> >
> > Sorry, I thought I made the point that an AWD or 4WD system is only as
> > capable off-road if it has a way to lock the transfer case. (In fact,
> > the GM product mentioned has such a thing.......)
> >
> That may have been your point, but this is what you typed:
>
> 'Any system of AWD/4wd that can be used on pavement WILL NOT perform as
> well off-road or in real severe conditions'
>
>

Well technically your 4wd system can't be used on road while your AWD
system can. Just like my 2wd can but my 4WD mode can't.
--
____________________
Remove "X" from email address to reply.
 
Chris Phillipo wrote:
> In article <rcyPb.69938$Es.27959@news-lhr.blueyonder.co.uk>,
> exit@nomore.com says...
>> Matt Mead wrote:
>>> On Wed, 21 Jan 2004 11:32:49 GMT, "Exit" <exit@nomore.com> wrote:
>>>
>>>> My full-time 4WD works very well on-road and has a solid mechanical
>>>> diff that locks the front and rear axles together completely making
>>>> it identical to a part-time 4WD system when off-road.
>>>>
>>>> --
>>>> Julian
>>>
>>> Sorry, I thought I made the point that an AWD or 4WD system is only
>>> as capable off-road if it has a way to lock the transfer case. (In
>>> fact, the GM product mentioned has such a thing.......)
>>>
>> That may have been your point, but this is what you typed:
>>
>> 'Any system of AWD/4wd that can be used on pavement WILL NOT perform
>> as well off-road or in real severe conditions'
>>
>>
>
> Well technically your 4wd system can't be used on road while your AWD
> system can. Just like my 2wd can but my 4WD mode can't.

I think I'm falling foul of the different ways of describing 4WD systems
depending on what side of the atlantic you are again!

I can only use 4WD whether on or off road coz I have no other options. I can
use lowbox on or off-road also. The only thing I can't use when on road is
my central diff-lock.

--
Julian
---------
= Pretentious Sig required =


 
I'd say this is the perfect time of year to head down to the dealers for a
test spin ... try em out ... see what you think.


"RobertS975" <roberts975@aol.com> wrote in message
news:20040119164321.21837.00000318@mb-m14.aol.com...
> Looking at various Yukon XL/ Denali models. Is there an advantage to 4WD
vs AWD
> vehicles? My 97 GMC Suburban will go through deep snow if needed. Will a
newer
> AWD vehicle or a 4WD "when needed" vehicle perform as well? Advice needed!


 
That's the trick with open differentials. It sounds like you pretty much
know what you're talking about, so I won't go into huge detail.

An open differential in the axle provides equal torque to both wheels on
the axel. The torque is not equal on both wheels only when one wheel looses
traction.

Peg-legers is a very appropriate term for open diffs... in the racing world.
Because you're constantly feeding more torque to the drive wheels than the
tires can hold on to. Then it'll feel more like a 4X4 is really a 4X2, with
one front and one rear drive wheel.

But for those of us who are just looking to drive through some mediocre snow
drifts while on road, open diffs work just fine. Unless you have the bucks
to spend on locking diffs on the axels.

I read a lot about how open differentials = 1 wheel drive. It's just not
correct.

"g3_josh" <g3_josh@hotmail.com> wrote in message
news:1389f664.0401201843.29aa213d@posting.google.com...
> Let's not forget that in most stock 2WD/4WD vehicles (such as a 1984
> chevy pickup) the center diff. locks the front and rear drive shafts
> together but there are two more diffs, front and rear, and under most
> conditions these differentials only transmit power to either the left
> or right wheels. "Peg Leggers" in the drag racing world. In certain
> circumstances (when you are traveling perfectly straight with equal
> traction on both wheels) you can get the dif to lock up. So even if
> you have a 4X4 it doesn't mean you get power to 4 wheels.
>
> Today's AWD systems sometimes sense wheel spin and dynamically brake
> the wheels to transfer power "from the wheels that slip to the wheels
> that grip". Its a form of anti-lock brakes for accelerating. In
> effect you do get power to all 4 wheels.
>
> Josh


 

"Clem" <mygodisthereanamenotchosen@yahoo.com> wrote in message
news:1027i1l2u8t69f2@corp.supernews.com...
> That's the trick with open differentials. It sounds like you pretty much
> know what you're talking about, so I won't go into huge detail.
>
> An open differential in the axle provides equal torque to both wheels on
> the axel. The torque is not equal on both wheels only when one wheel
looses
> traction.
>
> Peg-legers is a very appropriate term for open diffs... in the racing
world.
> Because you're constantly feeding more torque to the drive wheels than the
> tires can hold on to. Then it'll feel more like a 4X4 is really a 4X2,
with
> one front and one rear drive wheel.
>
> But for those of us who are just looking to drive through some mediocre
snow
> drifts while on road, open diffs work just fine. Unless you have the bucks
> to spend on locking diffs on the axels.
>
> I read a lot about how open differentials = 1 wheel drive. It's just not
> correct.

Check this video:
http://www.quebeccrv.com/movies/QuebecCRVBouette.wmv

You can see how the big truck spins several wheels at one time.
You can also see that the CR-V spins a wheel in front and another one in the
back at the same time.


 
Paul Bielec wrote:
> "Clem" <mygodisthereanamenotchosen@yahoo.com> wrote in message
> news:1027i1l2u8t69f2@corp.supernews.com...
>> That's the trick with open differentials. It sounds like you pretty
>> much know what you're talking about, so I won't go into huge detail.
>>
>> An open differential in the axle provides equal torque to both
>> wheels on the axel. The torque is not equal on both wheels only when
>> one wheel looses traction.
>>
>> Peg-legers is a very appropriate term for open diffs... in the
>> racing world. Because you're constantly feeding more torque to the
>> drive wheels than the tires can hold on to. Then it'll feel more
>> like a 4X4 is really a 4X2, with one front and one rear drive wheel.
>>
>> But for those of us who are just looking to drive through some
>> mediocre snow drifts while on road, open diffs work just fine.
>> Unless you have the bucks to spend on locking diffs on the axels.
>>
>> I read a lot about how open differentials = 1 wheel drive. It's just
>> not correct.
>
> Check this video:
> http://www.quebeccrv.com/movies/QuebecCRVBouette.wmv
>
> You can see how the big truck spins several wheels at one time.
> You can also see that the CR-V spins a wheel in front and another one
> in the back at the same time.

Sorry - after 10 minutes of watching people drive backwards and forwards
through the same inch and a half of mud and ankle deep puddle I got bored.
Does anything interesting happen later on?

--
Julian
---------
= Pretentious Sig required =


 
Right, but when the wheels are spinning they aren't getting much traction,
whether it's 2 or 4 spinning.

If you aren't spinning the wheels, an open differential provides equal
torque to both wheels on the axle.

I have to say, though, that a couple of times this year on my way to work I
would have liked locking diffs in both axles on my jeep. She barely made it
through a couple of those drifts.


"Paul Bielec" <me@no.spam> wrote in message news:c01165$hn2$1@dns3.cae.ca...
>
> "Clem" <mygodisthereanamenotchosen@yahoo.com> wrote in message
> news:1027i1l2u8t69f2@corp.supernews.com...
> > That's the trick with open differentials. It sounds like you pretty much
> > know what you're talking about, so I won't go into huge detail.
> >
> > An open differential in the axle provides equal torque to both wheels
on
> > the axel. The torque is not equal on both wheels only when one wheel
> looses
> > traction.
> >
> > Peg-legers is a very appropriate term for open diffs... in the racing
> world.
> > Because you're constantly feeding more torque to the drive wheels than
the
> > tires can hold on to. Then it'll feel more like a 4X4 is really a 4X2,
> with
> > one front and one rear drive wheel.
> >
> > But for those of us who are just looking to drive through some mediocre
> snow
> > drifts while on road, open diffs work just fine. Unless you have the
bucks
> > to spend on locking diffs on the axels.
> >
> > I read a lot about how open differentials = 1 wheel drive. It's just not
> > correct.
>
> Check this video:
> http://www.quebeccrv.com/movies/QuebecCRVBouette.wmv
>
> You can see how the big truck spins several wheels at one time.
> You can also see that the CR-V spins a wheel in front and another one in
the
> back at the same time.
>
>


 
"Clem" <mygodisthereanamenotchosen@yahoo.com> wrote in message
news:1028iq74j2qe5c6@corp.supernews.com...
> Right, but when the wheels are spinning they aren't getting much traction,
> whether it's 2 or 4 spinning.

That's true and the stock tires on the CR-V are really good for spinning in
the mud.
The CR-V isn't an offroad vehicle neither. It was only because the video
shows clearly that it is not a 1 wheel drive car as you can see more than 1
wheel spinning when it is stuck.


 
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