Open Differentials vs. Traction Control vs. Lockers

[MikeHenderson]

Henderson, after reviewing your informative vid on traction aids for cross axle conditions, I would add some fringy items to your fine piece.
*One is the softness and articulation (aka; range of motion) of your springs whether leaf or coil.
*Another is the weight or lack of in each situation.
*Another is whether you disconnect your anti sway bars to add more articulation and have enough unimpeded travel (fender clearance and longer brake hoses). Here's the resulting articulation due to these items in the Little Sluice about 2004:
<a href="http://s194.photobucket.com/user/jefe4x4/media/FourWheelDrives/Jefe2 little sluice CJ-8.jpg.html" target="_blank"><img src="http://i194.photobucket.com/albums/z240/jefe4x4/FourWheelDrives/Jefe2 little sluice CJ-8.jpg" border="0" alt=" photo Jefe2 little sluice CJ-8.jpg"/></a>

I notice the Tundra had rather limited flex even with the camper on the back pushing down on the suspension. With 8 leaves on the rear of my RAM (5 on the main pack and 3 on the upper overloads) I should have less flex than the Tundra but I think it may be more:

and: click to open vid: This is going up the great sand drop off in Anza. To be clear, on this day in March my bro John tried this in his 1999 F-250/rr LS/ diesel/OUTFITTER! @ 30 pounds of air in 3rd gear/low. He didn't make it. TP too high (not enough floatation) and not enough momentum. About 1/2 way up he sank to frame and had to slowly back down keeping perfectly vertical. It was now my turn. After his experience he bade me lower my pressure to 20 pounds (just about bottom for a 10K pound truck camper even with wider super single wheels) and try the first part in 4th gear/low range. Near the top I downshifted to 2nd gear to get across the deep moguls. We both have 6 speed manuals. I have True Tracs front and rear which held fast through the moguls.
https://www.dropbox.com/s/bfj5y93wsd7vfkw/jefe does sand hill at dry wash of the devil Anza.m4v?dl=0
I notice a variety of outlooks on this thread, all based on their personal experience. It's a stretch to compare each situation as equal. I do not go looking to twist my axles up as that twist will transmit to the frame and truck bed and try to tweak the camper's frame, in essence trying to pull it apart. I avoid this at all cost, changing to a different line than normal off roaders would try. People in Jeep JK's would not have this worry.
jefe

Yes, suspension has a huge impact on traction for sure. But that's another video...

-M

 

[Buliwyf]

When an auto locker becomes a ''low side finder'', the fault is your tires, not the locker. IME, Truetracs and Lsd's start doing the same thing shortly after lockers do. Add tire chains, studs, even tire claws to your kit.

Generally, if I'm in 4wd the ''low side finder'' sliding of the truck is minimal. But in 2wd, turning on the rear locker, does make the truck slide violently down hill. I can usually mitigate the front lockers sliding with steering input. Front lockers don't seem to slide as much as rear lockers. Also keep in mind, that the Detroit slides a hair less than a locked selectable.

I only use the rear locker in 4wd, for the most part. On a bumpy uphill gravel drive, I might use it in 2wd to prevent wheel spin and making a mess of that drive. But that's high grip, the truck isn't going to slide anywhere.

I'll run front Detroit Locker, rear selectable locker all over the snow belt. That's my ''go to'' setup now. 99.9% of the time that the front auto locker may be a problem on ice, I can simply switch back to 2wd.

With selectables, I find they need a moment of travel before they can lock and unlock. Worse yet, if it's an OEM locker that won't even try until both wheels are going the same speed. Sometimes I only get one chance at something. Juggling a front selectable off and on, isn't for me.

 

[Metcalf]

My current favorite combo is an automatic FRONT locker and selectable REAR locker.

There are a lot of little intricacies that come into play with locking differentials when you start having to actually manuouver the vehicle in situations when open/open is not enough traction. This is what I call the '3-wheel drive' problem. ( from this point forward I will refer to lockers in this format 'front/rear' to save a little time ). On a 4 wheel vehicle with only a steering front axle, the front tires are going to be pointing in the direction you want to go, and the rear tires are always going to be pointed directly forward. No matter what you do to the rear axle for a differential or locker, it is going to want to push you forward. If you run the math on all 4 tires when they go through a corner, the REAR tires actually have the largest left to right speed differential on the vehicle. The front tires have some, but they are turning a LARGE radius than the rear tires. This issue can get much worse with varying degrees of steering angle and wheelbase. There is also a front to rear axle speed difference, and this is why full time 4wd vehicles have center differentials.

If all you need to do is go in a straight line, lock everything up and make everything turn the same speed. This is basically what happens on 4wd vehicles with front and rear lockers. When we start to have issues is when we need to balance the ability of the vehicle to turn AND have traction at the same time. Some modern vehicles can do this ok with traction control systems that brake the wheel, but there are still a lot of limitations.

I am going to try to break down the common issues I see with a LOT of current locker systems including factory systems like the Rubicon, old fzj80s, etc.

#1. Should be be locking the REAR differential first if the rear axle is always trying to push us straight? This tends to GREATLY increase the turning radius of the vehicle. It also typically causes the rear of the vehicle to slip downhill when you are having issues. We see this issue with all rear lockers typically, and especially in vehicles with only a rear locker. I am proposing if at all possible, that the FRONT locker be locked first.

#2. Most maneuverability issues, including that bound up can't turn feeling we all know too well, is coming mainly from the REAR locker. We need to be careful to separate steering force issues. Mainly being how hard it is to turn the wheel, vs how the vehicle is actually maneuvering. Most steering force issues I see are actually from scrub radius induced issues especially with a spool ( or locked selectable ) where there is no mechanism to help that issue. It isn't that the vehicle doesn't want to maneuver really, it is that you might not have enough force to turn the wheel. What I have found is that if you get the REAR locker off when you need to change directions, the steering force goes way down. This is true for a spool ( or locked selectable ) but is AMAZINGLY better if you happen to have a front automatic locker. If you unlock the rear axle, pretty much every single bad front autolocker trait goes away. With the front locked, the front tires are going to be pointing in the direction you want to go. Conversely, if you have the rear locker only, it will be pushing you wide and downhill typically.

#3. The main issue with every selectable locker we commonly see, is that they typically don't like to unlock until they are unbound. When you are trying to manuver, they are typically going to be bound up, espeically in a front axle application with a decent amount of scrub radius. An automatic front locker, especially when not getting pushed over by a rear locker, is happy to lock and unlock happily on it's own using it's ratchet function. The action of steering and the scrub radius can actually make the locker ratchet. This works especially well at slow speeds where you need it when trying to technically maneuver a vehicle.

What I have found, is that in a lot of cases, that an auto/selectable can work even better in a lot of situations than a selectable/selectable setup. You end up having to worry about pushing buttons a LOT less. You will notice a lot less overall bound up and being pushed through corners where you need 4wd vs the other options. I will say, if you drive a LOT of snowy/icy roads at freeway speeds in 4wd at speeds above 45mph that a selectable/selectable system may be a better fit. I have put a LOT of miles on my auto/selectable system and don't really find this to be a huge issue however. If you have full time 4wd I would also suggest that selectable/selectable setup will be better.

In the end, one of the major things that I have found is that we should look at using the front locker first if possible. You will feel a little more steering force feedback under power, but the vehicle will generally maneuver a lot better in 3wd when you need to change directions. Get that rear locker off as soon as you don't need it. I have found that I can do very difficult trails with very little rear locker use. I notice a big difference when I try the same things with rear locker only and the front open. I do own both these combos.......auto/selectable and selectable/selectable. When I build the next vehicle, it will be auto/selectable. I will likely add rear left/right/both cutting brakes to further decrease rear locker use and increase maneuverability. Beyond that, I will be using a transfer case that allows front wheel drive only also to provide even more ability to pull the front end around things.

 

[Metcalf]

I'm with Mundo here - any sort of auto locker is a big liability in many (not all) ice or snow situations. I was wheeling with a buddy in his Cherokee years ago w/auto locker in the back, tight 2-track road in the woods, slightly offcamber uphill, we went down ok.....but coming back up, we lost traction and the rig was sliding sideways 6" every time we would attempted to move forward / apply power. There was a 50' cliff on the side of the road. It's something a subaru / audi / any SUV could have made it up no problem. We were stuck in a sketchy situation. We wheeled all day with no problems in the snow but were screwed here.

I've also been in situations here in Oregon on some of paved highway passes where I've had to come to a stop around a tight bend / slight offcamber due to folks spinning out. I'd envision the same issues trying to apply power here also.

Things are obviously different in the SW, but anyplace where there is ice/snow, selectable is where it's at IMO.

Those sound like REAR automatic locker issues?

 

[MOguy]

Yes, suspension has a huge impact on traction for sure. But that's another video...

-M

In the video they showed vehicles with different suspension setups, and was apparent that they performed differently. Even thought they overlooked that in this video it is an essential part of this discusion.

 

[Metcalf]

In the video they showed vehicles with different suspension setups, and was apparent that they performed differently. Even thought they overlooked that in this video it is an essential part of this discusion.

I don't know, I don't think locker choice and suspension overlap that much honestly. Suspension is an interesting discussion in itself.

 

[MOguy]

I don't know, I don't think locker choice and suspension overlap that much honestly. Suspension is an interesting discussion in itself.

It all about traction and control. A limited slip will be far more effective in a suspension that has better articulation than a suspension that has less travel. If you are hanging wheels a locker will be a car better option, except lockers can make maneuvering more difficult, so can having a tire hang.

 

[billiebob]

If you care about the trails you wheel on you should do EVERYTHING you can to limit wheel spin, lockers and traction aids help. Swallowing you pride and using a winch or get pulled though is another option. Driver skill can only go so far. Tread lightly!

Even if you don't care about tread lightly having you vehicle work better will keep you from abusing you vehicle and getting stuck.

THIS ^^^^

TREAD LIGHTLY !!!

I go to our beach often. Most people park and walk down the steep drop off but a few os us drive. Coming back up is an exercise in digging holes and bouncing like crazy for everyone except those with Rubicons. No matter how chewed up the ruts are, 4L, locked front and rear, the Rubicons literally idle up. ZERO wheel spin, no drama, almost silent.

Lockers are all about TREAD LIGHTLY and save the equipment. Best investment ever. Way better than a winch.

 

[billiebob]

No doubt, the selectable locker is the best for slow going over rough transitions. Limited Slips are best for traction accelerating where speed is not limited. Torsen Difs are great in mud or anytime you can modulate both the brake and accelerator. But for control when you value your rig, the selectable locker, air or electric, is the best choice. And there are no wear parts in either open dif or locked dif modes.

 

[Happy Joe]

Just opinions, yours are likely different;
If not wheeling difficult trails, or harder, open diffs are often good enough; spinning tires indicate a need to upgrade the vehicle and or driver skills.
Selectable lockers are best; and almost never used on road...
Most limited slips are not as good, off road,and have no option to turn them off but since most don't really work much better than open diffs (often/usually due to internal clutch wear), its not a big deal.
Automatic lockers are not something that I will never use again; indeed, if I ever get another vehicle that has them pre-installed the first MOD will be to trash them and put in selectable lockers... this is not a big deal selectable lockers are typically put in my new old vehicles by the end of the 3rd month.

The Rubicon has OEM, lockable Torsen style diffs and so far (2 years in) they are OK although there are few/no internal replacement parts available so when (not if) they break they will get replaced by ARBs. Off road, without locking them, they are not great/desirable. Note; the stock placement of the differential locking switches is far from optimal/easy to use, without taking my eyes away from the trail, it will likely get changed this summer.
The, daily driven, Explorer has a front Torsen differential (couldn't find a front ARB for it, the rear 8.8 is ARB equipped), it is OK on the street and semi maintained roads (rear unlocked) but I would not class it as particularly good off road ('though, the vehicle is more limited by the IFS than the Torsen differential). Trying to modulate the Torsen using the brake is not my cup of tea (given a choice; I would not do it again). ...Trying to brake modulate the Torsen reminds me of the (not great) old days of trying to get a Power Lock to engage/stay engaged/jump up on the ramps by using the brake... might just be me but stepping back into the 1950s is no great advancement, IMO.

Enjoy!

 

[Metcalf]

It all about traction and control. A limited slip will be far more effective in a suspension that has better articulation than a suspension that has less travel. If you are hanging wheels a locker will be a car better option, except lockers can make maneuvering more difficult, so can having a tire hang.

I've seen just as many issues with too much suspension travel being quirky as I have not enough suspension travel being quirky. I like to find a happy balance.

Personally, I see very little need for anything over a 10" travel shock. I do a LOT of crazy stuff and something in that travel range seems to be a really good overall balance.

 

[Metcalf]

Just opinions, yours are likely different;
If not wheeling difficult trails, or harder, open diffs are often good enough; spinning tires indicate a need to upgrade the vehicle and or driver skills.
Selectable lockers are best; and almost never used on road...
Most limited slips are not as good, off road,and have no option to turn them off but since most don't really work much better than open diffs (often/usually due to internal clutch wear), its not a big deal.
Automatic lockers are not something that I will never use again; indeed, if I ever get another vehicle that has them pre-installed the first MOD will be to trash them and put in selectable lockers... this is not a big deal selectable lockers are typically put in my new old vehicles by the end of the 3rd month.

The Rubicon has OEM, lockable Torsen style diffs and so far (2 years in) they are OK although there are few/no internal replacement parts available so when (not if) they break they will get replaced by ARBs. Off road, without locking them, they are not great/desirable. Note; the stock placement of the differential locking switches is far from optimal/easy to use, without taking my eyes away from the trail, it will likely get changed this summer.
The, daily driven, Explorer has a front Torsen differential (couldn't find a front ARB for it, the rear 8.8 is ARB equipped), it is OK on the street and semi maintained roads (rear unlocked) but I would not class it as particularly good off road ('though, the vehicle is more limited by the IFS than the Torsen differential). Trying to modulate the Torsen using the brake is not my cup of tea (given a choice; I would not do it again). ...Trying to brake modulate the Torsen reminds me of the (not great) old days of trying to get a Power Lock to engage/stay engaged/jump up on the ramps by using the brake... might just be me but stepping back into the 1950s is no great advancement, IMO.

Enjoy!

I agree that automatic REAR lockers can be a huge headache, but once I tried one in the front (with a rear selectable) it changed how I look at them completely.

I believe only the rear locker on the Rubicon package has the limited slip when 'open' feature?

 

[Happy Joe]

I agree that automatic REAR lockers can be a huge headache, but once I tried one in the front (with a rear selectable) it changed how I look at them completely.

I believe only the rear locker on the Rubicon package has the limited slip when 'open' feature?

...Tried an automatic locker (Detroit) in the front worked great until I encountered a side hill in the snow...Too much fun! (white knuckley)... ended up moving the tree strap & snatch block from tree to tree along the upper side of the trail
with the winch cable hooked from front through the snatch block to my rear to keep me on the mountain for that part of the trail.
Friends that (don't, typically do snow runs but) do some pretty extreme trails, swear by them and I can see the advantage in good weather/with good traction.

I believe only the rear locker on the Rubicon package has the limited slip when 'open' feature?

..Now I'm going to have to pull the front cover and look (has a dent that needs straightening any how); If correct and there is no reason to think that you are not; it would explain why the Rubicon, unlocked, is so unimpressive.
Thanks!
...YAY! I can continue to drive it like it has ARBs (lock the rear at the trail head) and have even less incentive to fiddle ****** with the brakes when encountering a moderate difficulty.

Now I just need to investigate to see if the spare D44 ARBs that I have will fit...(If so, won't have to worry about breaking the, OEM, light duty rear L/S).... (starts looking for the ARB link)

Enjoy!

 

[Metcalf]

...Tried an automatic locker (Detroit) in the front worked great until I encountered a side hill in the snow...Too much fun! (white knuckley)... ended up moving the tree strap & snatch block from tree to tree along the upper side of the trail
with the winch cable hooked from front through the snatch block to my rear to keep me on the mountain for that part of the trail.
Friends that (don't, typically do snow runs but) do some pretty extreme trails, swear by them and I can see the advantage in good weather/with good traction.


..Now I'm going to have to pull the front cover and look (has a dent that needs straightening any how); If correct and there is no reason to think that you are not; it would explain why the Rubicon, unlocked, is so unimpressive.
Thanks!
...YAY! I can continue to drive it like it has ARBs (lock the rear at the trail head) and have even less incentive to fiddle ****** with the brakes when encountering a moderate difficulty.

Now I just need to investigate to see if the spare D44 ARBs that I have will fit...(If so, won't have to worry about breaking the, OEM, light duty rear L/S).... (starts looking for the ARB link)

Enjoy!

Happy Joe.

I am curious. When you tried the automatic front locker what REAR locker did you have?

I've run my little flat fender all over the place including hundreds of miles of deep snow wheeling up north. All the bad automatic locker traits went away with a REAR selectable locker. The front tires just go where I point them? Especially with the rear end unlocked. I rarely have to use the rear locker which is really nice.

 

[Happy Joe]

Happy Joe.

I am curious. When you tried the automatic front locker what REAR locker did you have?

I've run my little flat fender all over the place including hundreds of miles of deep snow wheeling up north. All the bad automatic locker traits went away with a REAR selectable locker. The front tires just go where I point them? Especially with the rear end unlocked. I rarely have to use the rear locker which is really nice.

I believe it was an old school/original design, Detroit Locker (not the soft locker)...It was in the '81 CJ-5... note; the soft locker is/was much more "civilized" but can still be a handful...was in the front.
One of my friends made it (the -5) into a rock buggy, on 38s, and he, too, tended to go more sideways than forward on slippery (packed snow and ice) side hills (with ARBs, unlocked, I was able to get across only having the rear slide downhill a little..

Enjoy!