AWD versus 4X4....questions

299 Views 8 Replies 7 Participants Last post by pleasesnow, Sep 29, 2006

mattie

Discussion Starter · Sep 29, 2006 (Edited by Moderator)

I understand the idea behind AWD. However, I've always had full-size 4x4's.

Whether it's "autotrac" or "controltrac", whatever the builders want to call it.....it appears to be the way everything is heading in the future.

I'm looking at a replacement for my existing truck. A couple I've looked at have full time AWD. No bull low. No full time 4WD. No 2WD either.

How do these fancy AWD's work as far as towing goes? One's got 9,000 lbs towing cap the other has 7,800 lbs.

I'm sure the AWD must eliminate some of the fun of powered 4 wheel drifts in deep snow. I still really prefer to know that the truck is in full time 4WD when needed.

Any opinions? Experiences?

Is the AWD stuff really intended for the soccer mom's & such?

In my mind, I imagine the vehicle retarding ignition, clutches slipping, whatever it takes to eliminate wheel spin. That would 'suck' to drive! Much less own.

Mattie

- help me out here people....

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Fancool

· #2 · Sep 29, 2006

Name some specific models, and I can tell you more.
But in general, the modern AWD systems use sensors to detect wheel slippage, then either use clutch packs or the brakes to re-direct power.

Regular 4x4 transfer cases use mechanical gears to evenly distribute power to both axles, but no Brains to stop 1 wheel on a axle from slipping and loosing power.

Jeep engineers had a good saying about a competitor using the ABS system to provide " Bettter " traction.

" Were no fans of impeding progress to provide progress"

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SS5150

· #3 · Sep 29, 2006

Jeep's quadra drive in the '99-'04 Grand Cherokees is a mechanical system with an oil pump and clutch packs in the diffs and t-case. No electronics involved here. The new G.C.s have electronic solenoids in the diffs, but haven't seen many problems with them. I'm not familiar with GM or Ford.

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mattie

Discussion Starter · #4 · Sep 29, 2006

Name some specific models, and I can tell you more.
But in general, the modern AWD systems use sensors to detect wheel slippage, then either use clutch packs or the brakes to re-direct power.

Fancool, I was looking at Yukon Denali's, Navigator, etc....

The AWD is a bit weird for me. Much prefer the 2HI, 4HI & 4LO systems.

I just didn't want to go back to crew cabs if I could help it.

mattie

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Bonvoyage Snow Adventures

· #5 · Sep 29, 2006

I am no pro, but have had vehicles with both systems.
My opinion--- AWD - much less traction in slippery conditions due to torque split of 35% to front and 65% to rear. More fuel consumption.
4 by 4- Much more confident feeling in snow while towing.
Hope this helps.

mattie said:
I understand the idea behind AWD. However, I've always had full-size 4x4's.

Whether it's "autotrac" or "controltrac", whatever the builders want to call it.....it appears to be the way everything is heading in the future.

I'm looking at a replacement for my existing truck. A couple I've looked at have full time AWD. No bull low. No full time 4WD. No 2WD either.

How do these fancy AWD's work as far as towing goes? One's got 9,000 lbs towing cap the other has 7,800 lbs.

I'm sure the AWD must eliminate some of the fun of powered 4 wheel drifts in deep snow. I still really prefer to know that the truck is in full time 4WD when needed.

Any opinions? Experiences?

Is the AWD stuff really intended for the soccer mom's & such?

In my mind, I imagine the vehicle retarding ignition, clutches slipping, whatever it takes to eliminate wheel spin. That would 'suck' to drive! Much less own.

Mattie

- help me out here people....

[snapback]914417[/snapback]

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zdooman

· #6 · Sep 29, 2006

Bottom line - unless your off road in the muck or climbing rocks - AWD is all you need.

There are many ways this is done and many have had some flavor of AWD even while being a 4x4.
Going back to something I am intimate with - Explorer - this system when you are in "2wd" is actually a smart AWD that sends anywhere from 3 to 35% of the power to the front when rear wheel slip is detected. Setting it in 4wd "locks' that to 50% power to the front. The losses are so small that attempts to go to locking hubs found no appreciable fuel savings and was dropped before ever making production.

Engine power reduction is only used in traction control systems to prevent wheel slip. It is not a function of an AWD system.

What effects towing capacity is not the drive type itself but the added wieght on the chassis. Your towing capacity is a funtion of the total vehicle wieght and the capacity of the springs / suspension to carry more of it. That is way a 2wd vehicle will always have a higher rating over the identical 4wd vehicle. That extra wieght of the axle, shaft and transfer case reduce the capacity of the chassis. Its nothing to do with the strength of the powertrain.

Like ABS, and soon to be across the board Stability control, most AWD systems can adjust and send the power where it is needed, when it is needed, with no input from the driver required.

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Fancool

· #7 · Sep 29, 2006

Zdooman is all over this one

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biggziff

· #8 · Sep 29, 2006 (Edited by Moderator)

Wife's Hyundai SF has the AWD. It's a unique system in that it's FWD until the viscous coupling clutches lock up to engage the rear wheels. I believe Hyundai is using the same system Lexus is using in their vehicles. No crazy tire wear, no clunks and a 65-35 split. It gives her tremendous confidence when the roads become slippery. She no longer worries about the road. It just works and she never feels a tire spin. Car goes anywhere my F150 can go.

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pleasesnow

· #9 · Sep 29, 2006

biggziff said:
Wife's Hyundai SF has the AWD. It's a unique system in that it's FWD until the viscous coupling clutches lock up to engage the rear wheels. I believe Hyundai is using the same system Lexus is using in their vehicles. No crazy tire wear, no clunks and a 65-35 split. It gives her tremendous confidence when the roads become slippery. She no longer worries about the road. It just works and she never feels a tire spin. Car goes anywhere my F150 can go.

[snapback]914944[/snapback]

I wish they would bring back locking hubs. And by the way, the super duties may have them, I know but they really only have auto and lock. I want the locking hubs to be free and lock. Too easy. Our work suv has the auto, and it works great.

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