Is 4WD much of a necessity?

[Ag&Au]

There are situations that have not been discussed yet, where 4WD will always beat 2WD either RWD or FWD. An example is encountered driving on beaches and other sandy areas where water is present. There are often narrow areas just below the otherwise uniform sandy surface where water is flowing very slowly (seeping). When you get both wheels of a drive axle in one of these invisible streams. you are going no farther unless you have 4WD or are going fast enough (which is usually too fast for the conditions) to allow momentum to carry you through. You can, and I have, also become need-a-tow stuck thinking you can drive through a narrow cross road stream or puddle without checking the ground under the water. I had the rear drive axle totally stuck in a puddle. Had the truck been 4WD, I would have been through it without a hitch, because the puddle was narrower than the truck's wheel base. The front axle was on solid ground with good traction.

So even though different types of differentials will have differing successes, when you have equal differentials, the vehicle with 4WD will have a very distinct advantange over a 2WD vehicle.

To address the original question. "Is 4WD much of a necessity?"-
First of all the word necessity is an absolute thing. It does not come in various degrees. Something is either necessary or unnecessary. So using that word, 4WD is unnecessary for towing 98.32% of the time. An individual must look at his typical towing environment and personal tendency to take chances, and decide what his chances are of encountering the remaining 1.68% of the time. He must also decide how much inconvenience he is willing to suffer if he does encounter that 1.68%.

Ken

[dznf0g]

Yes, Ken is correct. There are times and situations when nothing but 4wd will get you out. For ASers, we individuall have to look our situation and travel desires. For me, I will get a 4wd WITH a G80 locker. G80 is, I think, still under $500.

But, Ken, I think a healthy axle discussion is "on the question". There is a lot of confusion and lack of understanding to axle and diff offerings. Trying to clear that info up is essential, IMO, to deciding 2wd alternatives to 4wd and options in addition to 4wd.

[Ag&Au]

Originally Posted by dznf0g

Yes, Ken is correct. There are times and situations when nothing but 4wd will get you out. For ASers, we individuall have to look our situation and travel desires. For me, I will get a 4wd WITH a G80 locker. G80 is, I think, still under $500.

But, Ken, I think a healthy axle discussion is "on the question". There is a lot of confusion and lack of understanding to axle and diff offerings. Trying to clear that info up is essential, IMO, to deciding 2wd alternatives to 4wd and options in addition to 4wd.

I did learn quite a bit from the differential discussion. However it is somewhat difficult to put it all in perspective, due to the seeming disagreement about what term means what to different participants. However, I will file it away for the next time I buy a 4WD vehicle and use it for a basis to research what is available.

It was not my intent to say that the discussion was off topic. I am sure it will be valuable to anyone who buys a TV in the future. It just seemed that the point needed to be made that 4WD's relative worth or desirability is largely going to have to be decided by the purchaser, based on his own uses. I see how the title I chose could be taken as a statement that the discussion had gotten off topic. That was not the intent. It was just an announcement that I was going in a different direction.

Ken

[Jammer]

Originally Posted by dznf0g

I disagree wholeheartedly. Both the Eaton units discussed are lockers, with safety and driveability features incorporated to allow street use. Both the eaton units LOCK SOLID under all situations after engagement

My Suburban has the G80 "gov lock" diff. Dznf0g is absolutely correct -- this is a locking differential, not a limited slip one (I've had those too). The G80 diff has two modes of operation -- open and locked. When it's open, it's just like a garden variety non-locking diff with no torque bias at all. When it locks, it locks completely and there's no slip at all until the torque limit is reached as dznf0g describes.

[Jammer]

Originally Posted by JDS

Would you say that a 2 wheel drive pick-up with a "locker", such as the newly introduced 2014 GM 1/2 units, is a viable alternative to four wheel drive?

No.

First of all, as a practical matter, nearly all 4wd pickups and large SUVs are equipped with some sort of locking or limited-slip rear axle. So the 4wd is providing traction above and beyond that.

There have been all kinds of situations where my 4wd truck and burb were stuck in the snow, mud, or wet grass, G80 locking diff and all, until I engaged the front axle.

[dznf0g]

No worries, Ken!

[dznf0g]

Originally Posted by Jammer

No.

First of all, as a practical matter, nearly all 4wd pickups and large SUVs are equipped with some sort of locking or limited-slip rear axle. So the 4wd is providing traction above and beyond that.

There have been all kinds of situations where my 4wd truck and burb were stuck in the snow, mud, or wet grass, G80 locking diff and all, until I engaged the front axle.

I'm not sure about the standard thing. I'd have to re-review GMs offerings, but in 2013, G80 became a free flow option in, I think, all situations. It was even removed as standard in the tow package and left to the customer to decide if they wanted it or not. There may still be some trim levels and suspension packages where it is part of an optional package, but there are a LOT of 4wd running around with no LS or locker. It shuld be looked at closely when shopping or ordering.

For GM it'll be on the SPID label as "G80".

[Jammer]

Originally Posted by Ag&Au

I did learn quite a bit from the differential discussion. However it is somewhat difficult to put it all in perspective, due to the seeming disagreement about what term means what to different participants. However, I will file it away for the next time I buy a 4WD vehicle and use it for a basis to research what is available.

Again, I've had both, they both help, and neither is perfect. Lockers help more than limited slip, but it's a marginal difference. Most of the time, if you're stuck enough to spin one wheel with a limited slip rear, you're also stuck enough to spin both wheels with a locker. The performance of limited-slip diffs tends to deteriorate over the years and miles as the clutches wear. G80s work until they explode into 100 pieces at which point you probably can't drive the truck until you overhaul the rear axle -- though in many cases they last the life of the truck without attention. Other lockers have different failure modes but share the property of consistent traction performance up until the point of failure.

[dznf0g]

Originally Posted by Jammer

Again, I've had both, they both help, and neither is perfect. Lockers help more than limited slip, but it's a marginal difference. Most of the time, if you're stuck enough to spin one wheel with a limited slip rear, you're also stuck enough to spin both wheels with a locker. The performance of limited-slip diffs tends to deteriorate over the years and miles as the clutches wear. G80s work until they explode into 100 pieces at which point you probably can't drive the truck until you overhaul the rear axle -- though in many cases they last the life of the truck without attention. Other lockers have different failure modes but share the property of consistent traction performance up until the point of failure.

Again, we're close in agreement, but I think there is a big difference between LS and and lockers in a normal towing situation or boat ramp type of need. If we want to talk about solo off roading and solo deep snow, etc, I am closer to your opinion. But I think, as this is a towing forum, and most of us will never be hitched up in deep snow or off roading in mud while towing, (OK, some of you guys might!!!) I think it is important to keep my comments confined to the audience. If I were posting in an off-road forum, my conversation would be very different. I don't think a G80 is a whole lot better than LS in a HIGH PERFORMANCE off road situation, as opposed to a farmer crossing his fields and through the ditch, or a construction worker driving through the site at low speed.

The eLocker is probably better for high performance off-roading IF Ford didn't play with the calibrations and algorythums too much. I have no clue how robust it is in the shock loading department...which speaks to your "100 pieces" comment. Ford does prevent, and removes engagement at 50% throttle in 4hi and 2hi....presumably to prevent shock loading.

[Sylver Slypr]

Originally Posted by Jammer

My Suburban has the G80 "gov lock" diff. Dznf0g is absolutely correct -- this is a locking differential, not a limited slip one (I've had those too). The G80 diff has two modes of operation -- open and locked. When it's open, it's just like a garden variety non-locking diff with no torque bias at all. When it locks, it locks completely and there's no slip at all until the torque limit is reached as dznf0g describes.

The new generation of LSD(Locker) is actuated "exactly" the same way older LSD's were(Torque bias between axles) and when torque limit is reached it reverts back to a limited slip.(to avoid breakage)The difference is that there is not a clutch pack or spring pre-load there is a solid connection that locks the axles temporarily causing high stress conditions on driveline parts.LSD's do reach nearly 100% torque bias(both spin at same rate) in high torque conditions but it is gradual and forgiving depending on what type of LSD used.

[dznf0g]

Originally Posted by Sylver Slypr

The new generation of LSD(Locker) is actuated "exactly" the same way older LSD's were(Torque bias between axles) and when torque limit is reached it reverts back to a limited slip.(to avoid breakage)The difference is that there is not a clutch pack or spring pre-load there is a solid connection that locks the axles temporarily causing high stress conditions on driveline parts.LSD's do reach nearly 100% torque bias(both spin at same rate) in high torque conditions but it is gradual and forgiving depending on what type of LSD used.

Could you give me a brand and model of that type of LSD? I'd like to read up on it. GM doesn't use truck LSDs and I am unfamiliar with what you describe. That is, however, different than a G80 or an eLocker.

[Sylver Slypr]

What happens in extreme conditions where traction is required above the 20 mph threshold of a "Locker"

[dznf0g]

Again, speaking from a road use and towing perspective, traction control and stability control is better than any LS, or locker, in my professional opinion, once at speed. And actually I would choose AWD/TC/SC in that scenario over 4wd.

In an off road situation, you present the problem that OEMs have when building for the public at large. Thus my distinction between my position on this forum vs. an off road forum, for example.

[Sylver Slypr]

In an off road situation, you present the problem that OEMs have when building for the public at large. Thus my distinction between my position on this forum vs. an off road forum, for example.[/QUOTE]
35 mph up an icy road in the snow (which is possible in August at high elevations) is not IMO an off road situation.Slippage can occur at any speed you know.

[dznf0g]

Originally Posted by Sylver Slypr

In an off road situation, you present the problem that OEMs have when building for the public at large. Thus my distinction between my position on this forum vs. an off road forum, for example.

35 mph up an icy road in the snow (which is possible in August at high elevations) is not IMO an off road situation.Slippage can occur at any speed you know.[/QUOTE]


Yes, and electronic traction control with stability control and now electronic sway control all work very well in that situation. Limited slip (the kind which is always engaged) actually interferes with the second stage of traction control (the individual wheel ABS stage) as when applied to RR, for example, it affects LR as well. Kind of makes for a 3 channel system instead of 4 channel. An open diff at higher speeds (ON ROAD SLIPPERY CONDITIONS) is better with electronic aids. I also prefer AWD in this scenario, for its front/rear variable torque splitting capability. (But, alas, no low set in the t-case for low speed grunt work.)

[Sylver Slypr]

The True-trac LSD is an automatic full-time no maintainence Friction/Traction control device that is easier on drivetrain components in all conditions and superior to a part time high stress Locker that must disengage (to "open" status and re-engage to lock) to protect itself and the drivetrain from catastrophic failure.All the while it compromises traction while protecting itself in this situation and it still provides no traction aid above 20 mph.To each his own,intended use and personal preferences and needs are what should determine what system is optimal for an individual TV as the circumstances and conditions are different and can be addressed with many options. P.S. the electronic traction control could force the True-trac to act more like a locked rear by transferring torque faster and limiting slippage.

[dznf0g]

What OEMs use True-trac? Your last statement is true, but here's what I found back in the early days of ETC. Back then we used more aggressive TC in low speed/high loads situations, just as you describe (came into play more with open diffs than G80). While effective in some situations as a "diff lock"...sort of, it could bog down to the point that so much brake was being applied that the truck just stopped. Momentum was lost, then you were kind of potentially screwed. But the big thing, was this system ate brake pads/shoes very quickly if the truck was in slippery low speed, high load conditions a lot. I think there might be one manufacturer out there that calls this a limited slip or locking rear axle (can't remember which) and claims less axle maintenance (true), but totally neglects the accelerated brake maintenance.

[Sylver Slypr]

none

[dznf0g]

Ok, I thought so, but wasn't sure enough to say. Here's the thing. This is a thread where the question is "I'm truck shopping for an AS TV...do I need 4wd" I have tried my darndest to stay on track with what's available off the lot to help someone make a decision on what's available 2wd/4wd from the factory. If the question was, "What can I do to modify my truck to get more traction?" then there are A BUNCH of aftermarket stuff we can talk about...much of it not suitable, or overkill, for AS towers. I don't want to hijack this thread to make it a truck forum mod thread.

I suppose if someone wants to start that kind of thread, that's ok, but they are probably better served on a truck forum. Not trying to lecture.....just trying to maintain decorum.

[Sylver Slypr]

I don't think adding the Eaton True-trac will void warranty,but it is considered "aftermarket" even though it is a major supplier to the big three.