Go Back  The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > Dockside Chat
Reload this Page >

Another Question About AWD SUV's

Notices

Another Question About AWD SUV's

Old 10-18-2016, 06:36 AM
  #1  
Senior Member
Thread Starter
 
Join Date: May 2006
Location: Suffolk, Va.
Posts: 17,009
Default Another Question About AWD SUV's

Over the years all of my SUV's had AWD and 4 wheel drive. The SUV I just purchased for my wife only has AWD. I'm assuming it has a transfer case to transfer power to the front wheels so why wouldn't the car also have 4 wheel drive? Can I drive a AWD car on the beach like a 4x4? Is AWD also considered 4 wheel drive?
fishingfun is online now  
Old 10-18-2016, 06:53 AM
  #2  
Admirals Club Admiral's Club Member
THT sponsor
 
williamwallus's Avatar
 
Join Date: Jun 2014
Location: SWFL, Midwest
Posts: 3,236
Default

AWD will generally transfer power as needed

drive it on the sand for sure, ive plowed through 4ish feet of snow in my AWD with no issues
williamwallus is offline  
Old 10-18-2016, 07:00 AM
  #3  
Senior MemberCaptains Club Member
 
ladyjane's Avatar
 
Join Date: Jan 2008
Location: lake champlain vermont
Posts: 30,178
Default

My wife's pilot has a button that says it will lock all tires in below a certain speed I have used it once coming out of a snow bank seem to grab better . So sand I would say yes do people still air down on sand?
ladyjane is offline  
Old 10-18-2016, 07:31 AM
  #4  
Senior MemberCaptains Club Member
 
Join Date: Oct 2007
Location: Davie / Islamorada
Posts: 12,255
Default

my Land Cruiser has full time AWD ... and sucks down fuel as a consequence .....
triplenet is offline  
Old 10-18-2016, 08:12 AM
  #5  
Senior MemberCaptains Club Member
 
Join Date: Dec 2003
Location: Northern Neck, VA
Posts: 5,340
Default

as above, yes. you can drive anywhere in anything....
until you get stuck

Hope it has some buttons or wizardry to "lock hubs" or it may not be as good as old school 4x4 in the real muck and mess.


but then again 99% stay on the streets.

Honestly I have only had my 4x4 beast (f250) in 4 wheel drive once in the snow and once at a bad ramp in the last 4 years...
rocksandblues is offline  
Old 10-18-2016, 08:27 AM
  #6  
Senior Member
 
Join Date: Aug 2016
Location: Sunset Bay, TN
Posts: 163
Default

Originally Posted by fishingfun View Post
Over the years all of my SUV's had AWD and 4 wheel drive. The SUV I just purchased for my wife only has AWD. I'm assuming it has a transfer case to transfer power to the front wheels so why wouldn't the car also have 4 wheel drive? Can I drive a AWD car on the beach like a 4x4? Is AWD also considered 4 wheel drive?
This will vary from vehicle to vehicle... Most AWD for primarily front wheel drive and only send power to the rear wheels as needed and as commented many have nothing more than one button to allow for locking the power distribution to all wheels and nothing else, some full-time AWD may not even give you that option; these will tend to wear tires and burn more fuel...
teecro is offline  
Old 10-18-2016, 09:33 AM
  #7  
Senior Member
 
Join Date: Jan 2011
Location: Charleston, SC
Posts: 325
Default

AWD would have an open transfer case. Meaning that if you loose traction to one wheel the car will not move. 4wd has a locking transfer case. If you loose traction to one front wheel and one rear wheel the car will not move. Most cars now have anti lock brake systems that stop the spinning wheel to deliver the traction to the wheels that are not moving. Some vehicles (off road vehicles) offer locking front and rear differentials to power all four wheels all the time.
whitefethr is offline  
Old 10-18-2016, 09:37 AM
  #8  
CME
Admirals Club Admiral's Club Member
 
Join Date: Mar 2010
Posts: 3,839
Default

I have a work van with it. Won't do that again, very poor fuel economy.

Last edited by CME; 10-18-2016 at 09:51 AM.
CME is offline  
Old 10-18-2016, 05:48 PM
  #9  
Admirals Club Admiral's Club Member
 
Join Date: Nov 2007
Location: Long Island, NY
Posts: 8,340
Default

Originally Posted by fishingfun View Post
Can I drive a AWD car on the beach like a 4x4? Is AWD also considered 4 wheel drive?
Assuming it has decent ground clearance, the answer is yes. You really don't need a lot of traction in the sand - you need the vehicle to float, which is why airing down is critical in softer sand.
AWD is technically a type of 4WD, but most AWD vehicles are primarily front wheel drive with a transfer case that sends some power to the rear wheels - not the best for serious off-roading. None of the AWD vehicle have locking differentials, and instead rely on the braking system to keep the wheel that is slipping from spinning - it does work, but only at very low speed.
LI32 is offline  
Old 10-19-2016, 03:35 AM
  #10  
Senior MemberCaptains Club Member
 
Join Date: Jul 2006
Location: RI
Posts: 6,438
Default

I did not register my truck for the beach this year here in RI but I heard through someone that they now require 4 wheel drive and no longer allow AWD. You may want to check into that in your area.

There are also different AWD systems including locking center differentials, high and low gear selectors, locking rear or limited slip differentials, etc.

As already pointed out, the beach requires you to float, not traction. I ran a 26' class c with two wheel drive out on the beach for years and never got stuck. Come close a few times. Had matching tires all around but the were the largest I could fit without the dually's rubbing on the highway.
BACKTOTHESEA is online now  
Old 10-19-2016, 03:59 AM
  #11  
Senior Member
 
Join Date: Jan 2015
Location: Norfolk, Va
Posts: 654
Default

As stated AWD tends to only send power to the front when there is a "need". Look for a way to lock the AWD for when you want true AWD. My mothers Murano had AWD with a "lock" button. Did ok on the beach in the OBX.
Spruill242 is offline  
Old 10-19-2016, 04:06 AM
  #12  
Admirals Club Admiral's Club Member
 
Join Date: Nov 2007
Location: Long Island, NY
Posts: 8,340
Default

Originally Posted by BACKTOTHESEA View Post
I did not register my truck for the beach this year here in RI but I heard through someone that they now require 4 wheel drive and no longer allow AWD. You may want to check into that in your area..
If that is true, and they truly mean 4WD, then the beaches will be pretty empty - 4WD means locking (limited slip or true locker) front, center and rear differentials. There are only a handful of current vehicles made that meet that requirement: Jeep Wrangler with Rock-Trac, Jeep Grand Cherokee with Quadra-Drive II and Offroad II and Mercedes G-Class. Toyota stopped putting the locking diffs in the Land Cruiser, and Range Rover stopped in their new models too; nothing ever built by Ford or GM (except the Hummer H1), or any of the other foreign builders except Toyota and Land Rover ever had limited slip or locking front differentials.
LI32 is offline  
Old 10-19-2016, 04:18 AM
  #13  
Senior Member
 
Join Date: Apr 2015
Location: Chesapeake
Posts: 2,548
Default

Originally Posted by LI32 View Post
...None of the AWD vehicle have locking differentials, and instead rely on the braking system to keep the wheel that is slipping from spinning - it does work, but only at very low speed.
Not always true. Many have the ability to lock up. Our Honda Pilot is an AWD version, which primarily funtions as FWD above 10-15 mph. If wheel slip is detected at high speeds, some power will be transferred to the rear tires. At low speeds, power is distributed between all 4 tires (with a bias to the front unless slip is detected), and there is an option to lock the rear differential (not to be used on dry pavement.)


Originally Posted by LI32 View Post
If that is true, and they truly mean 4WD, then the beaches will be pretty empty - 4WD means locking (limited slip or true locker) front, center and rear differentials. There are only a handful of current vehicles made that meet that requirement: Jeep Wrangler with Rock-Trac, Jeep Grand Cherokee with Quadra-Drive II and Offroad II and Mercedes G-Class. Toyota stopped putting the locking diffs in the Land Cruiser, and Range Rover stopped in their new models too; nothing ever built by Ford or GM (except the Hummer H1), or any of the other foreign builders except Toyota and Land Rover ever had limited slip or locking front differentials.

We once had to tow a Grand Cherokee out of a sand trap that we had negotiated without much difficulty in our Pilot. It was funny watching all four wheels spinning and digging a deeper and deeper hole.

Last edited by The Spit; 10-19-2016 at 08:49 AM.
The Spit is offline  
Old 10-19-2016, 08:32 AM
  #14  
Senior MemberCaptains Club Member
 
Join Date: Jul 2006
Location: RI
Posts: 6,438
Default

Originally Posted by LI32 View Post
If that is true, and they truly mean 4WD, then the beaches will be pretty empty - 4WD means locking (limited slip or true locker) front, center and rear differentials. There are only a handful of current vehicles made that meet that requirement: Jeep Wrangler with Rock-Trac, Jeep Grand Cherokee with Quadra-Drive II and Offroad II and Mercedes G-Class. Toyota stopped putting the locking diffs in the Land Cruiser, and Range Rover stopped in their new models too; nothing ever built by Ford or GM (except the Hummer H1), or any of the other foreign builders except Toyota and Land Rover ever had limited slip or locking front differentials.
I think what they are after are all these AWD cars or car like cross overs that simply do not have the clearance to be out on the trails. I did quickly look at the reg's and do not see a restriction.
BACKTOTHESEA is online now  
Old 10-19-2016, 10:11 AM
  #15  
Senior Member
 
Join Date: Sep 2006
Location:
Posts: 3,150
Default

4wd and AWD aren't strictly technical term. Thank marketing BS for the confusion.
Milehog is online now  
Old 10-19-2016, 12:16 PM
  #16  
Admirals Club Admiral's Club Member
 
Join Date: Nov 2007
Location: Long Island, NY
Posts: 8,340
Default

Originally Posted by The Spit View Post
Not always true. Many have the ability to lock up. Our Honda Pilot is an AWD version, which primarily funtions as FWD above 10-15 mph. If wheel slip is detected at high speeds, some power will be transferred to the rear tires. At low speeds, power is distributed between all 4 tires (with a bias to the front unless slip is detected), and there is an option to lock the rear differential (not to be used on dry pavement.).
Actually it has the ability to lock the center differential (VT-4 Lock button) - on the Pilot (and we have had 4 of them), it has open front and rear differentials, and uses the anti-lock brakes to control spin on the front and rear axles.

Originally Posted by The Spit View Post
We once had to tow a Grand Cherokee out of a sand trap that we had negotiated without much difficulty in our Pilot. It was funny watching all four wheels spinning and digging a deeper and deeper hole.
That is just a failure to air down - pretty much any vehicle is fine in the sand if the air pressure is right; where the locking differentials are indispensable is for rock crawling - and they help in deep snow too.
LI32 is offline  
Old 10-19-2016, 01:32 PM
  #17  
Senior Member
 
Join Date: Apr 2015
Location: Chesapeake
Posts: 2,548
Default

Originally Posted by LI32 View Post
Actually it has the ability to lock the center differential (VT-4 Lock button) - on the Pilot (and we have had 4 of them), it has open front and rear differentials, and uses the anti-lock brakes to control spin on the front and rear axles...
Yes, you are correct on that-- it is actually the center diff that gets locked with VTM4, not the rear diff. Thanks for the correction.

Fortunately the limited slip feature (via ABS) can be disabled on our Pilot, since it will often cause a vehicle to get stuck in soft sand or other conditions when you need to be able to spin tires to keep moving.
The Spit is offline  
Old 10-19-2016, 01:37 PM
  #18  
Senior Member
Thread Starter
 
Join Date: May 2006
Location: Suffolk, Va.
Posts: 17,009
Default

Sorry, the SUV in Question is a 2007 Mercury Mountainer 8cyl rear wheel drive with AWD. It does have a button to activate the system.
fishingfun is online now  
Old 10-19-2016, 04:46 PM
  #19  
Senior Member
 
crazybeard's Avatar
 
Join Date: Aug 2013
Location: Tropico
Posts: 5,804
Default

Lots of well intentioned but not completely accurate info here.

AWD is full time. Whether that is a 90/10 front bias, 50/50 or whatever other bias it just means that all wheels are powered. Including a rear biased setup. Some are 40/60 if they want the car to act more like a RWD handling wise. Some "AWD" are 100% front until slip is sensed. There is no set rule of how it should be designed.

There are a number of ways so sense slip and distribute power accordingly. Wheel speed sensors, also used for ABS, traction control, stability control etc and some systems (traction control) will brake the slipping wheel in order to stop it from spinning.

To put power to a non-spinning wheel the system has to have a mechanical way to do so via a differential. There is typically 3 of them on an AWD or 4WD vehicle. In some cases (not nearly as common) there is no center differential.

Open diff is the cheapest to make. It is also the most forgiving for inexperienced drivers because you can spin a wheel without shoving a massive amount of power to the other side and causing the vehicle to slide. Think pickup truck smoking one back tire.

Limited slip on the other hand, will let a wheel spin to a certain limit (hence the name) based on a % of faster spin than the other side for whatever % it was manufactured.

Many AWD will have a combo of types. Some, like certain Audis have 3 torsen differentials, arguably some of the best style you can have for an AWD vehicle.

4WD can be full time or part time, and . The unofficial but commonly accepted difference between 4WD and AWD is that 4WD vehicles have a low range selectable in the transfer case.

Transfer cases are used in various 4WD and AWD vehicles. All it does is transfer the power from the transmission output shaft to 2 different shafts for front and read drive, and optionally has a low range for 4WD vehicles.
crazybeard is online now  
Old 10-20-2016, 05:17 AM
  #20  
Senior MemberCaptains Club Member
 
ladyjane's Avatar
 
Join Date: Jan 2008
Location: lake champlain vermont
Posts: 30,178
Default

Originally Posted by The Spit View Post
Yes, you are correct on that-- it is actually the center diff that gets locked with VTM4, not the rear diff. Thanks for the correction.

Fortunately the limited slip feature (via ABS) can be disabled on our Pilot, since it will often cause a vehicle to get stuck in soft sand or other conditions when you need to be able to spin tires to keep moving.
Depending on how much you drive on slippery surfaces it will wear the breaks out faster. I did my breaks at 40,000 We drive on slippery surfaces all winter gravel roads snow covered with ice .I turn the traction control off but I tell my wife to leave it on because it keeps her on the road
ladyjane is offline  

Thread Tools
Search this Thread