Collective wisdom on 4wd systems

[John Boyce]

I am thinking about trading our Ram Cummins (06 2500 Quad Cab Long Box) in on an SUV type vehicle. In fact, it's listed for sale in the Classifieds. My wife and I don't really need the hauling capability of the truck any more, and a smaller vehicle would make more sense for our needs. Our main need for a four wheel drive vehicle is to get to and from our house in the badlands of western North Dakota. This involves about 120 miles of driving on the interstate, 10 miles on gravel roads, and about a mile back in to our place. Ice and snow are the main concern, as is drifting snow, particularly on the way up to our house. I have had the Cummins stuck in snow drifts in our road several times. That's when my four wheel drive John Deere tractor comes into play. I've never had it stuck, yet, but it was close Saturday morning.



My only experience with four wheel drive vehicles is with the traditional (primitive?) system we have on our truck, where there is a transfer case that is either in our out, and live axles, perhaps with limited slip on the rear (as on our current 2006). I learned with my first such vehicle (a 75 Jeep Cherokee) that "four wheel drive" really means one front wheel and one rear wheel when you're in slippery stuff, and it's not hard at all to get such a vehicle really stuck! On the interstate, this kind of four wheel drive works ok, but you're constantly shifting the transfer case in and out according to road conditions. I had a Chevy truck once that had an "auto 4wd" setting that was supposed to kick the front axle in when the rear end started to slip.



I was wondering how the more modern all wheel drive systems, particularly those on the higher-end SUV's said to have decent off-road cred (Cayenne, Range/Land Rover, Grand Cherokee, Land Cruiser) would handle snowy/icy highways and drifted back roads. These vehicles have sophisticated systems that use the transfer case, axles, and brakes to sent torque to the wheel(s) that have traction, and do so on the fly. They also have traction and stability control systems to help prevent skids. Do any of you have real-world experience with these kind of vehicles in winter weather? To my knowledge, such systems are not available on pickup trucks, perhaps for reasons of load rating and/or cost.



I understand the importance of good tires for snow and ice, and in fact our front wheel drive Saab station wagon with four winter tires is a far better winter highway vehicle than our truck. One of my concerns is that many of these newer SUV's now come with 18 inch (or larger) wheels and fairly low profile tires, which, to me, isn't ideal for snow.



Thank you for any input you may have.

 

[Road Dog]

I think you're confusing 4WD with AWD systems. 4WD have a transfer case (usually 2 speeds) where the front and rear drive shafts turn at the same speed. AWD have a center diff so the drive shafts turn independently and can be as simple as an open diff and as complicated as viscous clutches under computer control. Subaru and Audi seem to have the best AWD with traction control system which are great for cruising down a snowy highway but they're not off road vehicles. They have ok ground clearance and poor approach/departure angles. (The current crop of American SUVs are even worse -- they're lower and add air dams in the front for even less clearance. )

A simple AWD/traction control system adds complexity with zero benefit. It's all about marketing -- how little can the manufacturer do to claim "AWD & Traction Control".

Traction control is designed for on pavement use -- wet and icy snowy roads -- not loose surfaces like gravel. Some systems have a disable button and a very few have a knob to select pavement or gravel (or ON road and OFF road).

I think I'm rambling but all these systems are different and you need to research how they work.

 

[p-Bar]

AWD = a lot of moving parts to wear out better budget in a extended warranty

 

[DWordinger]

John, you and Road Dog both touched on this. An AWD system uses brakes to prevent slipping. An AWD vehicle won't get stuck in the snow as easily as a 2WD, but when it gets stuck, it's stuck. One wheel starts slipping so the computer applies the brake on that wheel. Other wheels slip so the brakes are applied there. Now you have one wheel trying to push the vehicle forward while skidding the other three locked up wheels. If there is too much wheel spin, the computer will figure too much torque and throttle back the engine, regardless of what you are trying to do with the accelerator pedal. That is a bit of a simplification, but I don't thing by much. My wife's Honda has AWD and I've had to pull it out with my 4WD truck. A person I work with has an Audi and he states the AWD system is a poor excuse for 4WD.



Jeep has different drive train combinations available on some of it's vehicles. My understanding is some of them have an "intermediate" position between 2WD and 4WD that is similar to AWD. That is what I would look into.

 

[JMetzger]

I don't know about all there is to know about AWD. We have a 2002 Ram 4WD & we just bought a Dodge Journey AWD & so far I have had no problems in snow. We went from Gardnerville, NV to the Bay Area in a snow storm across RT 88 & both my wife & I felt that it did as good a job or better than the Ram with 4WD. There was about 8-10 inches of snow and we had no problem. We both are very satisfied with the Journey & AWD.

 

[Gonzo 1066]

I think that you would be hard pressed to do better than a Jeep Grand. Well thought out vehicle that has real 4x4 capability. IMHO

 

[AH64ID]

An AWD SUV would do you well. The weight distro and traction of AWD will do exactly what you need. We have a '03 V6 4Runner and it does amazing in the snow/ice. It also has selectable drive options to include 2wd, AWD hi, AWD lo, 4WD hi, and 4WD lo. Each of these modes also has some sort of traction control and stability control. I have found that AWD does better in snow/ice than 4WD due to the way the computer aids traction.



But thats just one example, there are many modern rigs that will do you quite well.

 

[guldam]

My wife drives an AWD Honda Element. We both have driven up in the mountains in nasty snowy conditions, icy roads etc, and the Element has performed perfectly. Road gets slippery and the AWD kicks in. I have no regrets buying this car. And it feels rather cavernous inside compared to most SUV's.

GulDam

 

[John Boyce]

Great discussion so far, thank you. For the record, the SUV's I mentioned all have dual-range transfer cases (the 2011 Cayenne doesn't, but it's out of my price range), and I think all of them can be locked. I am quite sure that the traction control can be turned off if wheel spin is required. They are all known as capable off-road vehicles. They aren't simply AWD highway vehicles like Subarus or crossovers, which are not under consideration by any means. The Wrangler Unlimited is a nice looking vehicle, but I'm not impressed with the power train, and we already have a Wrangler (a 4 cylinder soft top, which isn't much of a highway vehicle). I am looking for something that is safe and comfortable on the interstate, and that will get us all the way to our house in almost any weather. The Ram Cummins certainly isn't bad; it's actually quite good; but it's just more vehicle than we need.

 

[Cosmo]

There's a lot of bogus info in this thread.

I've got quite a background in AWD vehicles, having owned 5 Subarus, 3 "full-time 4wd" Jeep Grands, 2 full-size Dodge 4x4's, a Dakota 4x4, a Bronco 4x4, and having been a crew chief for an off-road rally team for about 10 years, and I'm now a Subaru mechanic.


What do you want from your vehicle? Any of the above I have owned can easily do what you've stated in your original post, however some do better than others.

If you're looking for something that will tow ~6000 pounds and gets 15-20mpg highway, then a 4wd/AWD SUV would be a good choice. If you never need it to tow, then I'd highly recommend getting more of a car-based SUV or even a car.

You have to be smart about what you're getting though, you can't just say "I want a Grand Cherokee" and think you'll be fine. Unless you get a rear limited slip or better yet the Quadra-drive system, you'll find that it performs identically to your Cummins in slippery stuff.

My Dakota had an open rear diff - as did my 86 Ram and 96 Bronco. Locked center diff and open front/rear means 1 front/1 rear spinning.


My '01 Subaru, however, with a limited slip in the rear and a set of snow tires installed - it was virtually unstoppable. My '91 Subaru wagon with all season tires and an open rear diff was able to plow fresh powder up to the headlights with zero problems - I had guys in lifted 4x4's pulling over to let me by on the forest roads.

I've never had an AWD system that used the brakes - all of mine have been low-tech straight AWD. The best setup by far that I've owned was my '02 Grand Cherokee Limited with the HO 4. 7 v8 and Quadradrive - gerotor pumps front, center, and rear, and lots of power.

Newer fancy systems use the brakes, electronic throttle control, and other electronic trickery to compensate for crappy driving. I prefer mechanical systems.

If I were to be in your situation and wanted something relatively inexpensive with moderate fuel economy, towing capacity, and excellent off road abilities, I'd get another 02-04 Grand with the HO 4. 7 and Quadra-drive.

If I wanted something less "trucky" that got better fuel economy at the expense of towing capacity, I'd get a Forester.

 

[MChrist]

If you don't mind spending the $$$, check out the Audi Or the VW Touareg. V6 diesel, high quality. Audi is either an A5 or A7, can't remember.

 

[BimmerAgent]

'11 Grand Cherokee

This is what my new Limited has: Quadra-Trac II®

This active full-time system functions in all-wheel-drive until additional traction is needed, then reacts by electronically engaging the clutch pack to transfer up to 100% of the torque to either axle. This system also features 2. 72:1 LOW-RANGE and NEUTRAL.



Just drove 400+ miles thru snow, high winds (50+ mph), and black ice, and this vehicle performs. Pentastar V6, 20 mpg at altitude at 80 mph. Awesome comfort, control, and stability. Selectable drive modes like a Range Rover. This thing is awesome. I found it to be reasonably priced, but you'd have to make that call. This one should be on your short list. Bruce

 

[SBall]

John,
AWD vehicles are acknowledged to provide the best and safest handling on icy roads over 4WD due to the center differential that allows each wheel move at its own speed while preserving traction. The viscous center differential systems seem to be the least expensive, but the torsen systems used in the Audi and other vehicles have obvious advantages. For torsens to work though, you'll need good snow tires on all corners as they rely on a mechanical bias ratio to apply and distribute torque.

That said, having the ability to lock the center differential can be beneficial at times, something usually available in more purpose-built 4WD vehicles.

The vehicle that (in my feeble opinion) that offers all the attributes to dig through snow the best with high ground clearance, torsen (lockable) center differential, and reliability, would be a Toyota FJ cruiser with the manual transmission. With good snow tires and a set of Thule or Pewag chains in the back seat in case you encounter really deep stuff, you'd be all set! The deal breaker could be the poor gas milage and premium fuel design.

Steve

 

[Regcabguy]

Kudos for the Subaru products. My sister never had a problem getting to her job during Oregon's ice storms. Super reliable and now,very roomy as well. My buddy has a Subaru dealership here and rarely sees warranty issues. We've had great luck with our Honda Pilot also. I think the suggestion of winter tires might be the most cost effective suggestion though.

 

[steved]

If I wanted something less "trucky" that got better fuel economy at the expense of towing capacity, I'd get a Forester.

The newer Forester uses electronic controls on the brakes to get better traction... between my 97 Outback and my 09 Forester XT, my 97 actually handles snow better at speed, while the Forester will crawl better out the driveway. They operate differently... the 97 is "locked" and releases during turns whereas the Forestor "locks" when it senses slip (regardless of what others may say, this is real world experience with both my cars).



I've been happy with both my Subarus... my 97 Outback will walk circles around my truck in snow. As several eluded to before, if your dealing with snow; buy a separate set of winter wheels and have a good set of snow tires installed... that will make any AWD/4wd perform well in snow/ice.



And further, regardless of the car; its the DRIVER that typically makes the difference...

 

[AH64ID]

The vehicle that (in my feeble opinion) that offers all the attributes to dig through snow the best with high ground clearance, torsen (lockable) center differential, and reliability, would be a Toyota FJ cruiser with the manual transmission.

I agree, aside from the manual trans this is essentially the same drive-train that can be found in the 4Runner, Sequoia, and Land Cruiser. They all offer a similar center diff (appropriatly sized), but the TRAC and A-TRAC programming is all the same logic (some switch variations). I have had 2 rigs with A-TRAC, one was the 4runner I mentioned with AWD the other was a Tacoma without AWD but the A-TRAC was very impressive in 4WD, almost always better than the rear locker.



I wouldn't be shy about the toyota automatic's. I have had both and the newer auto's are smooth, long lasting, and still provide excellent control on snow and ice. The only down-fall to the Manual FJ is that the drive-train is Full-Time only, where you can still go part time on the auto.



Another feature Toyota offers is called Auto-LSD. I am not sure what rigs its offered on, but my 07 Taco had it and wow that really works well! You get the benefits of an open diff on snow/ice but the traction of a really good LSD.

 

[pwerwagn]

I have owned nearly every 4wd vehicle. In fact, I've never even owned a 2wd except a race truck. I currently own 3 jeeps, 4 dodge 4x's, and a Class 7 ranger.



I totally, 100%, second the 99-04 Grand Cherokee vote. I have an 02 with the quadradrive and 4. 7HO. Its fast, gets 20+mpg nearly everywhere, and the quadradrive ACTUALLY WORKS!! I have 2 70's dodges with spools in the rear, ARB's up front, etc, and this grand cherokee works 99% as good. The Vari-lok diffs actually will transfer power to the other wheel, even with one in the air. The T-case locks in low, and works great transferring power in high. Ive towed our boat with it a few times just to see, and it tows pretty good.



I have 3 grand cherokees now (2 95 ZJ's and the 02 WJ), which I have substituted for the TJ wranglers we used to own (a 97, 99 sahara, and 05 rubicon). The Rubicon had selectable lockers and all that stuff, and worked great. But honestly, the grand cherokee has twice the power, gets better mileage, and with the small lift will basically go anywhere the rubicon did in more comfort, half the price and a smoother ride. I had no intention of the QD grand becoming our "trail" vehicle, it was simply a new ride for the wife to haul the kids in because the TJ's sucked with car seats. It has now replaced every wrangler we own. It has a mild (2" front, . 75" rear) lift, good shocks, and 31's. We dont do "hard" trails with it, but it will do everything our rubicon would do.



The WK grands also have quadra drive, and have the hemi in them if something newer suits you. My complaint is they are IFS (the newest ones are IRS as well), and IFS has never been a friend of mine. I realize you are probably looking at newer vehicles, so even at that... the newer Grands get my vote out of anything else out there. OR, if you like the commander, its the same basic vehicle as the 05-09 (?) grands, but with a lil more room and a 3rd seat. My sister has one and loves it. The 05+ grands with the hemi are a lil heavier than my 02 WJ, so even though its a decent amount more hp, its not any faster due to the weight.



I drove our WJ for the first time in snow this winter, and having owned a "decent" winter car, a WRX/STi, I was hoping this thing would do as good. Its every bit as good, and definitely better in the deeper stuff obviously. It works great on ice and packed snow roads, every bit as sticky as the STi. And its nearly as fast, gets better mileage, and has way more room.



Hope that helps...

-Jeff

 

[Shadrach]

Here is some info on the different systems that Jeep offers: Jeep - 4x4 Basics - SUVs, Sports Utility Vehicles, 4WD, Off-Road 4x4s

And for general 4x4 info see: Answers to your 4 wheel drive questions and off-road training by Harald Pietschmann.

Thanks for bringing up this subject as I have ben trying to learn more myself. I currently have a Jeep Cherokee, a Toyota Highlander and my 03 Dodge.
Shadrach

 

[rbattelle]

I am looking for something that is safe and comfortable on the interstate, and that will get us all the way to our house in almost any weather. The Ram Cummins certainly isn't bad; it's actually quite good; but it's just more vehicle than we need.

I thought I'd mention one possibility nobody else has: the Land Rover LR4.



While I have no first-hand experience with it, I've read it's 4wd system is something to write home about. If it's in your price range (starts at $48k), it would certainly be comfortable, powerful, and capable.



-Ryan

 

[Cosmo]

Land Rover systems are fantastic, but I would be leery of the reliability of the vehicle in general. Most Rover guys start ignoring dashboard warning lights unless the lights aren't on - a friend's Rover had "the three amigos" that were always on.