Limited Slip Faceoff: Detroit TrueTrac vs. ARB Air Locker


Entrepreneur & Lifehacker
Trying to decide whether I should put an Eaton Detroit TrueTrac limited slip differential on my 2003 Ford F250 diesel, or an ARB locking differential.

I plan on putting a pop-up camper in the bed of the truck and hitting some trails; probably at a max difficulty rating of 5 or 6. No crazy offroading, but want to be able to get in & out of remote beach locations in foreign countries, etc.

I'd start with the rear diff; possibly doing both front and rear at the same time.

Here are the pro's & con's as I see them -- anyone have any other suggestions?

  • Passive limited slip, nothing to maintain or engage/disengage
  • Brakes may need to be applied to engage differential in some situations
  • Does not fully lock axle... possibly easier on the drivetrain
  • Costs around $500

ARB Air Locker:
  • Fully locks the axle so power is always transferred to both wheels, even if one is off the ground
  • Has to be manually locked/unlocked
  • Requires on-board air compressor
  • Costs around $1k

I'm leaning towards the TrueTrac as it seems to be more passive w/ less that could go wrong. I am, however, planning on installing an on-board compressor regardless, and I like the idea of having fully locked axles for the most challenging situations... but at half the price and apparently able to handle 90% to 95% of the situations I might find myself in, I'm thinking TrueTrac is the way to go. Anyone have an opinion on this assessment?

Here are notes from my research about the TrueTrac


[FONT=georgia,serif] (it looks fromt this one like you sometimes may have to apply the brakes a bit to get both tires to turn)[/FONT]

"The Truetrac is useless in the rocks and if you have one tire off the ground forget it. With an ARB you get the beefy case and the choice of an open diff for street driving and a full locker when you need it." [FONT=georgia,serif] from ... also from that thread "I've had True Tracs and a light tap of the brake or couple clicks on the e-brake are usually enough to get both tires turning, even with one off the ground. The True Trac also beefs up the differential (case). I've run most Southern California trails with True Tracs front and rear (in a Jeep) and made all but the top 5% or so of the trails with relative ease. I did have to tap the brakes from time to time, so it's pretty nice for all but the most extreme situations. You also can't tell it's in the front diff because there are no clutch packs "grabbing", it's much smoother than most other "clutch" based limited slips." ... as well as ... "If I'm heading down a dry waterfall with one front tire hanging 4 feet in the air the last thing I want to be doing is tapping my brakes to "fool" the Truetrac into giving me power to the opposing wheel. Sounds like a recipe for a nose over. Now this is my rock crawler I'm refering to here, not the tow rig. I think LS and the like are good for street [FONT=inherit !important][FONT=inherit !important]trucks[/FONT][/FONT] if I'm crawling through 4-5 foot rocks I want lockers. But now that I've been using the ARB I can't see using anything else."[/FONT]

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[FONT=verdana, geneva, lucida, lucida grande, arial, helvetica, sans-serif]"the feedback that I have received from customers indicates that the unit works very well for mud and snow, while going unnoticed during every day driving. When used in situations like rocky trails where one wheel gets off the ground, the unit will not lock up 100%. Light application of the brakes will help the differential engage more transferring power to the tire that is still on the ground. For extreme situations where the vehicle will have one wheel in the air often a locking differential provides better power transfer to the wheel on the ground. " from[/FONT]
[FONT=verdana, geneva, lucida, lucida grande, arial, helvetica, sans-serif]

[FONT=verdana, geneva, lucida, lucida grande, arial, helvetica, sans-serif]"Traction is so good fellow club members don't believe I'm running LSDs and not lockers." from also "I have True-trac's front (D44) and rear (D60) in my TJ. Great traction. I thought I might regret not putting a locker in the rear but the True-trac has proven me wrong."[/FONT]
[FONT=verdana, geneva, lucida, lucida grande, arial, helvetica, sans-serif]


I went with the ARB in both ends. My primary concern came down to winter driving. Having a selectable locker is more predictable when roads glaze over. An open diff will allow one wheen to roll if the other loses traction. When the need for both wheel to spin, it is just a flip of a switch away. I have been scared to the point I needed to stop and check my underwear when the limited slip locked up mid corner while driving in the snow.


Bigassgas Explorer
Depends on your budget. If the high cost of admission for the ARB is not a problem, by all means go for it. It doesn’t get any better than an ARB selectable locker. On the other hand, if you are more on a budget, the TruTrac is the best bang for the buck. While it is no ARB airlocker, it is plenty strong and durable and beats the heck out of clutch type limited slips.

I run a TruTrac in the front of my truck while my buddy runs an ARB in the front of his. On dry trails I never even notice the TT is there but once you get it in the snow, you know it is alive! It seems the TT requires about ¾ to a full rotation of one tire before it locks up the other, which is why it is such a great limited slip for a steer axle. On the other hand, that can also be a problem when you need traction on dry ground. I mean, who wants to spin one tire almost a full rotation on boulders before the other side kicks in? Tire spin is bad especially on heavy truck like ours, that is when things start to break. That said, my buddy’s ARB can easily be turned on and off at any moment, any terrain and would be much more useful if added traction would be needed on dry ground. Like I say, it doesn’t get any better than an ARB but TT are pretty darn good for the money. I definitely want to upgrade to an ARB but yet I do not regret purchasing a TT. It is just time for an upgrade.


Entrepreneur & Lifehacker
@larry and @betarocker -- you both make great points about the pro's of the ARB full locking approach. I'd really appreciate hearing more about how the TrueTrac performs in snow -- especially around corners. I can imagine what you mean, where it causes instability around corners in the snow. But what if I only put the TrueTrac on the rear differential? And maybe keep the front open?

@larry re: budget -- I want to make the decision that's best for the truck and our use of it vs. saving a few hundred bucks.

Looks like I'll have to keep thinking this one over. Any other feedback is appreciated.


Entrepreneur & Lifehacker
@betarocker, how do you feel having an ARB in the front? How often do you engage it vs. the rear? Was it worth putting on the front, or would rear have been enough for most situations?


I have two ARBs in my rig.
Unless I'm on a real technical trail such as Rubicon or Dusy/Ershim, I almost never engage my front locker, and even the rear gets locked pretty rarely (I just spent 9 days out in the Panamint Mountains and not once did I use either locker). I s'pose my rig's supple suspension is helping too though.

I would say the TrueTrac probably would suit your needs fine, however like was said, if you got the budget, a selectable locker is extremely hard to beat.


I don't use the front locker much, but there have been a few times it would have meant using the winch had I not had it.


Third idea

Before making a decision either way, make sure you really need one. If you are doing 5,6 trails (on a 10 scale) then you may not even need either one. Good driving skills can do a lot towards getting a fellow through some rough stuff. If you do find that you need something extra to get you through, then go with a rear first and again see how you do.
Airing down and skillful choice in choosing a line makes a big difference. My philosophy has always been not to add anything until I have a proven need. Of course I would not have had to fix my door if I had put on sliders before getting into rough stuff. But usually the wait and see method works well. I have followed some folks with open dif's, 31 inch tires and no lift and been very impressed with where they go. Good luck on your choice.


Expedition Leader
I suppose I am biased (I have ARB air lockers in two of my 4WD trucks), but the air lockers are hard to beat if you can afford them. Fully locked when you need them and completely open diffs when you don't, the best of all worlds in my opinion but YMMV. Never driven anything with a TrueTrac on it so I have no opinion there.


I went from dual ARBs to a single Aussie Locker in the rear in my truck about a year ago now. I used the front locker 3 days out of the 6 years I had them and even then it was only a few minutes at a time.

Snow and slick roads have not been nearly as much trouble as I expected, but I have a fairly long wheel base and next to no power. I can get the truck to fishtail but I have to try. Honestly they are more annoying on dry pavement with the ratcheting, banging and driveline wind-up.

If I was to start at square one, it would have been with a good limited slip.
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Renaissance Redneck
I had f+r ARBs in my '03 Tundra. Loved them. If you can afford it, and want an on-board compressor anyway, it's the way to go. I used the lockers quite a bit, but the compressor saw the most use. I would start with ARB in the rear, and then add front when or if you find the need for it.


How about one of those units that are L.S. until you engage to fully locked. Put it in the rear axle. If I was going to put money in my axle that's where it would go. My Tundra has a factory optioned L.S. rear axle. It's all I need for trails that are full size friendly and won't beat up my rig. I had a locked Willys CJ3a that could/did go most anywhere, but that's a whole different type of trail rig. A truck and camper rig isn't going to be lofting wheels and rock crawling, well not for very far anyways.


Expedition Leader
I have had ff/rr ARB's on two rigs that were for rockcrawling, factory ff/rr lockers on two LC80 style landcruisers and the factory rear locker on a Tacoma. My current truck and camper hauler has the factory Gov-loc rear diff and I added an Eaton E-locker in the front diff. My Wrangler has the factory lockers front and rear.

On my truck after getting the front locker installed, I went out and tried it out. It took a few tries to find a spot where the factory gov-loc wouldn't get me through. I actually had to find a rutted out hill climb to find out whether the front locker was doing my any good.

I have found that while out in the backcountry with my truck/camper, I rarely use the front locker, but when I need it, I need it. Even with my camper, the front still weighs more than the rear, so that is a factor. I hit two seperate trails this last week, that I needed the front locker to get to the summit. The first one was steep rutted out, loose rocks and the second had me climbing an uneven rock ledge.

Here is a picture of the ledge, the picture doesn't do it justice, but the locker changed it from a tire spinning episode to a smooth crawling event.

And here is truck crawling up and over it.

I would recommend at least one full locker or both if you can afford it.



Expedition Leader
In my Dodge I run a factory rear Powr-lok.
In my Willys I run a rear powr-lok and a front autolocker ( Spartan lunchbox style locker )

Honestly, I think lockers are not really need as much as people think. Most people give up A LOT of performance by not airing down there tires properly. I always generally recommend that people invest in a winch before aftermarket lockers. If your vehicle comes with them stock that is great, but you WILL get stuck at some point and need recovery gear. A grumpy old man once told me, " all that fancy 'stuff' will just get you stick further from home, what you need is a winch ". This was back in my younger days when it was all about lockers, big tires, multiple transfer cases, etc. We traveled in a pack so getting a strap out of a bad situation was easy. Once you start traveling alone the requirements change.....

There will be trails or situations where even lockers won't get you where you want to go. Do you turn around at that point, or do you use the winch?


If you are going to install a locker I would recommend it be installed in the rear axle which tend to be stronger. The limited slip goes up front where you will need to have some forgiveness to protect the typically weaker front axle with u-joints, stub axles, locking hubs etc. Now if you are running solid axle D60's front and back with a smallish tire you shouldn't have much issue with a locker out front but if you have a D50 which is basically a D44 you will start breaking.

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