Locker vs Open

[Scott Brady]

And this accounts for for virtually all of the light pick-ups being used out there.

But almost zero of the vehicles on this site, and most OHV sites. The vast majority will be heavier in the rear than the front, or at least balanced 50/50.

That rule only applies to perfectly level ground when the driver is not turning. This is also almost zero percent of the time on a trail.

When weight is shifted like this over an open diff it only helps the open diff gain traction.

That would be true on perfectly level ground. Most climbs are not perfectly level, but have crossed axle holes, rocks, etc. that will cause one tire to exceed the tractive force of the other, sending all of the power to a spinning tire. Again, the front has little effect on a serious climb, maybe 20-30% of the available traction.

When weight is being shifted off of an open diff it causes it to loose traction. I want the front that is going to be loosing traction to spin both tires before I want the back which is gaining traction to spin both tires.

I think you want to re-read the above statement...

In all real-world driving conditions in technical terrain, a rear locker will have better tractive effect in 80% or more of cases. When you consider the effects of weight transfer on climbs, steering, axle strength, etc., there is no advantage to installing a front locking differential before a rear one.

 

[Hank]

And this only remains true if the front of the vehicle is heavier than the rear and/or has less articulation than the rear.

And this accounts for for virtually all of the light pick-ups being used out there.

I don't think so. My D1, for example, has a front axle weight of 2668lbs from the factory. In the rear, the weight on the axle is 3572lbs (not sure if that's with a full gas tank or not).

Most of your "kit" is added to the rear of the vehicle. You'll have a winch/bumper up front, but that's about it. That's why, if possible, I like to keep my tools and spare parts in the foot well of the back seat - that keeps additional weight in front of the rear axle and low. Even on the roof rack, if possible, I'll load the heavy stuff toward the front of the rack. Weight shifted past the rear axle works against you.

 

[jh504]

expeditionswest

Also let me say that I respect your knowledge, I am judging from my own past experiences which I pointed out in my first post. Those experiences are probably not as well versed as yours and are limited to a few vehicles on the same type of terrain(granite-mud). Be sure, that the next time we are out I will be paying very close attention to the different characteristics associated with the lockers on different types of obstacles.

 

[jh504]

I don't think so. My D1, for example, has a front axle weight of 2668lbs from the factory. In the rear, the weight on the axle is 3572lbs (not sure if that's with a full gas tank or not).

Most of your "kit" is added to the rear of the vehicle. You'll have a winch/bumper up front, but that's about it. That's why, if possible, I like to keep my tools and spare parts in the foot well of the back seat - that keeps additional weight in front of the rear axle and low. Even on the roof rack, if possible, I'll load the heavy stuff toward the front of the rack. Weight shifted past the rear axle works against you.

Understood, when I said pick-ups, I meant trucks with a bed and not SUVs.

 

[eleblanc]

If i had the choice to where i wish to have a manual or selectable locker, yes it would be front. If i'd be on a budget, i would get a automatic aussie locker in the rear and a ARB in the front. Otherwise ARB front and rear.

you have no idea how many time i can engage disengage my front locker just to steer around tree. I seriously have no idea how you could drive with a full time locker in the front.

Even my bj42 after a good fight with the front engage, my power steering fluid is so hot it is splashing out of the canister.

Yes i broke a birfield on my BJ, no it's really not fun to remove a axle in the trail under rain. That is why i now have longfields. If you put a locker up front be prepared for the worse, bring tools...tarp, towels, it is messy.......

 

[jh504]

I think you want to re-read the above statement...
.

The statement is said how I meant to say it.

When weight is over the rear, the rear being able to flex, it will keep the tires planted in all but extreme situations. I dont need both tires to turn if they are both planted.

 

[R_Lefebvre]

Install a locking differential in the front axle second, as it only contributes to 20% in the gain of tractive performance overall. The front should ONLY be fitted with a selectable locking differential. An open front differential would be a better choice than a mechanical locker or LSD for overland travel. The only people that will disagree with me are the drivers that use their vehicles exclusively in the deserts (and associated rocks). Once you start driving on snow, ice, mud, loose/cambered slopes, anything but a selectable front locking differential is not appropriate IMO. The one possible exception is the helical-style front LSDs, but they still create significant understeer on ice and snow, and some understeer in mud.

For real? I was planning on eventually doing the TruTrac front and rear on my truck. I've heard that it works well in combination with the TC, and it avoids scope creep (get a locker, now you need stronger axles, etc). I also like the way it operates on my Focus.

I have never heard before that an LSD would hamper turning on the front of a 4WD? I know it helps turning on a FWD. Or are you saying that it's the sideslope issue that's a problem? Never attempted that in a car, but I know it tramlines heavily sometimes on rutted roads.

 

[jh504]

If i had the choice to where i wish to have a manual or selectable locker, yes it would be front. If i'd be on a budget, i would get a automatic aussie locker in the rear and a ARB in the front. Otherwise ARB front and rear.

you have no idea how many time i can engage disengage my front locker just to steer around tree. I seriously have no idea how you could drive with a full time locker in the front.

Even my bj42 after a good fight with the front engage, my power steering fluid is so hot it is splashing out of the canister.

Yes i broke a birfield on my BJ, no it's really not fun to remove a axle in the trail under rain. That is why i now have longfields. If you put a locker up front be prepared for the worse, bring tools...tarp, towels, it is messy.......

Agreed, I would not put anything but a selectable in the front.

 

[Scott Brady]

The statement is said how I meant to say it.

When weight is over the rear, the rear being able to flex, it will keep the tires planted in all but extreme situations. I dont need both tires to turn if they are both planted.

Unless the slope is perfectly level and the surface traction is the same on both sides, one tire will spin if the hill is steep enough. Just because the axle has articulated, and the tire is in contact does not mean there is enough contact pressure/deformation/adhesion to keep the tire from spinning, which is precisely why you run a locker in the rear. An open differential by nature will distribute torque to the axle shaft with the least resistance.

By having a front locker only, you have little benefit from the front tire with traction that is turning, and no benefit from the rear tire that has the majority of the tractive potential in the drivetrain.

 

[TeriAnn]

Understood, when I said pick-ups, I meant trucks with a bed and not SUVs.

A pickup with an empty bed can be a different can of worms. I remember my dad driving his up steep dirt roads with my sister and I standing on the rear bumper & hanging on the tail gate (long before they passed that silly law about not being able to ride in the back). Even with our weight back there the pickup's rear tended to dance up the road.

BUT How many people go out on a long trip with an empty pickup? Usually when doing expedition style travel one gears up adding weight to wherever there is space. But yeah, when I think about it, I can see where someone out on a day trip with an empty bed pickup might have different traction issues. But that's also why they may not make it up and through places that their more weight balanced cousins can go.

Personally I'm a fan of a balanced weight vehicle with the rear axles carrying a few hundred pounds more than the front. If I accidentally go a little too fast for the trail (of course which I would never do) and find my vehicle momentarily airborne I prefer to land on all four springs instead of just the front two. I also prefer to have my centre of gravity a little aft of the vehicle centre so the vehicle tends to stay level with the rear wheels a little more than the fronts. It feels more stable to me that way and I would rather have a front wheel hanging than a rear wheel lifted.

Fully loaded my front axle weight is 2460 lbs (1117 kilos) and my rear axle weight is 2980 pounds (1353 kilos). That's with all three fuel tanks full (42 US gallons), the 15 gallon built in water tank full, the fridge fully stocked me in the front & a 130 lb plus dog in the back.

 

[Hank]

For real? I was planning on eventually doing the TruTrac front and rear on my truck. I've heard that it works well in combination with the TC, and it avoids scope creep (get a locker, now you need stronger axles, etc). I also like the way it operates on my Focus.

It works very well, but it's not locker.

You also have to consider the D2 hubs. They're famous for going out, and once they do, your TC no longer functions.

The best thing for the D2 is to install a CDL and disable the TC when off-road. D2 owners will tell you this is a night and day difference.

As for a LSD vs locker, it's a no-brainer, to me. Especially if they're the same price. Adding "HD" axles is a must in either circumstance. I ran stock axles with a Truetrac up front for some time. In the end, I broke 4 stock CV, 2 AEU2522 CV, and two inner shafts before going "HD".

The "you do not need HD axles with a truetrac (in a rover)" is a huge myth. The truetrac will only allow up to 80% of the power to reach one wheel, but even that's enough to snap the stock junk when off-road. This may not be the case in a Toyota rear axle, but it is the case in your D2.


[/QUOTE]I have never heard before that an LSD would hamper turning on the front of a 4WD? I know it helps turning on a FWD. Or are you saying that it's the sideslope issue that's a problem? Never attempted that in a car, but I know it tramlines heavily sometimes on rutted roads.[/QUOTE]

Turning with an LSD is not a big deal.

 

[Scott Brady]

For real?

Yes. Many people run TrueTracs in the F/R of the DII, as combined with the traction control the performance is quite impressive on dry, loose, rocky surfaces and on most hill climbs. But this assumes that the traction control is working (which on my 2001 often did not) and that you are not on icy, snowy, cambered or muddy terrain.

This does not mean that a TrueTrac is not a great diff., just not better than a selectable locker.

 

[Scott Brady]

expeditionswest

Also let me say that I respect your knowledge, I am judging from my own past experiences which I pointed out in my first post. Those experiences are probably not as well versed as yours and are limited to a few vehicles on the same type of terrain(granite-mud). Be sure, that the next time we are out I will be paying very close attention to the different characteristics associated with the lockers on different types of obstacles.

Thank you.

These are all valuable discussions, and one we have not had on ExPo to this level of detail. This is a good and informative debate to have.

 

[TeriAnn]

You also have to consider the D2 hubs. They're famous for going out, and once they do, your TC no longer functions.

The best thing for the D2 is to install a CDL and disable the TC when off-road. D2 owners will tell you this is a night and day difference.

CDL? TC? Need I be on LSD to figure these out?

For those of us who do not have "Mighty Ducks" version 2 (D2), could you please take the time to write things out instead of using initials? My initial code book doesn't cover Land Rovers newer than 1983 and isn't necessarily convertible to other marque initials.

No need to do this for past postings, but it would help me figure out what is being said on future postings.

Thanks

 

[I Leak Oil]

Thinking about some of this now I can honestly say in my limited experience with my own truck the only time my front locker was more beneficial than the rear (only running one or the other) was on a steep and slippery hill climb that really had no other obstacles like logs or ruts. When I tried the rear locker or both locked the rear end just kept walking out to the side. With just the front locked it pulled up pretty straight.
I think most would agree that given a choice of front or rear the rear would get the locker first. I've used the rear much more than the front.
So much of this is subjective and depends on the driver, the truck, the terrain so it is good to hear others experiences and try to apply what they have learned.
Jason T.