My Truetrak has about 40,000 miles on it with heavy duty axles, I lived the D35 dream, Sheared the axle spline right at the case and pieces of it took an adventure through the spider gears, wasn't pretty. Went to DTS in warren and bought the truetrac and axles and set-up kit and did it myself, 3yrs later still no issues, I'm not an extream off roader but when it happened I bought what they (DTS) suggested for a D35. I really appreciate the patience cause I new the locker thing with you guys was probobly overcooked but i didn't see anything satisfactory in the archive so I asked to see what you experts would suggest. In my trade (Machine Building) I have built all kinds of precision stuff and can rebuild anything on that vehicle but applying what works on a jeep, well all of you people are tried and true and I am always hoping to learn.

Post deleted by BigJim

"But the thing is a LUNCHBOX LOCKER.."

BigJim, what is "the thing" that you're referring to in the above statement? Fred talked about several devices in the post you quoted, and I'm not sure which one you're referring to here.

Your explanations are really helpful and I love Brown's website. Some things I can get right away but this one I had to work at. I have a rear limited slip differential and I thnk I got it now.
One more question (really two), and I am afraid to ask - (1) how does front-wheel drive figure in to a locker discussion - does it? I drove a Nissan Sentra front-wheel-drive for years (until I got the Jeep) and it was very good in the rain and especially in the snow, but this was on paved roads. Jeeps generally don't have front wheel drive. (2) I assume front wheel drive is less effective on trails than 4wd but better than rear 2wd? (And I hope you're not thinking, If she could ask this, she doesn't get it.)

Mine is a Truetrac, it acts like a limited slip, as per instalation instuctions, Final test: Drive on pavment with right side wheel on dirt accelerate. As you accelerate, the wheel with the least traction(right wheel) should spin momentarily. The spinning wheel should then slow down and synchronizw with the oppisite wheel as the Truetrac differential transfers power from the low traction wheel.

Now if I'm understanding this lunchbox thing, it is a unit that installs inside of the case that the ring gear is bolted to.
My Trutrac replaced my entire case.

differential case: A housing, mounted to and driven by the ring gear, which drives the differential spider.

differential Carrier: Component used to mount the differential assembly on the rear axle housing.

So the lunchbox style (Eaton EZ locker) does not pose a threat to the integrity of my factory case? But makes my Jeep very unstable on the street if i don't have locking hubs.
Is this a correct statement?

Your description of a limited slip differential (LSD) is correct. The point at which the slippage will lessen is called bias. Some LSDs have low bias, others have high bias. The lower the bias, the more mannerly the LSD will be on the street, but the less usefull it will be offroad. A high bias LSD will be more useful offroad (deep snow, dirt, sand) but may be more of a handful on slick pavement. Some LSDs are capable of having their bias adjusted.

There are basically two types of lockers: (1) Automatic, and (2) Selectable. The EZ Locker, LockRight locker, and Detroit locker are all esamples of automatic lockers. The ARB locker (pneumatically activated) and the Ox Locker (mechanically activated) are examples of selectable lockers.

All automatic lockers essentially act the same: the two axle shafts are locked together, unless one is coasting around a corner; in that case, one of the axle shafts disengages, and power is only applied to the other wheel. When the vehicle straightens out, and the tires are going the same speed again, the two axle shafts are locked together again. In some occasions, if power is applied during a turn, the two axle shafts will abruptly lock oether again - this can get squirrely on the street. Even is one axle shaft is disengaged, applying torque to only one rear wheel can cause the vehicle to swerve. Automatic lockers in the front axle don't present a problem on the street, as long as one is in 2WD and power is not applied to the fron axle. It is not necessary to unlock the front hubs if you have a front locker - it is only necessary to not apply power to the axle. This is assuming that your locker is operating correctly and unlocks one wheel when coasting in turns. If you're in 2WD, the front axle is always coasting.

Selectable lockers, on the other hand, are always either locked or unlocked, as determined by the driver.

The term "lunchbox lockers" does not refer to the operation of a locker, but refers to the construction of the locker. If a locker replaces the entire differential (except for the R&P gears), including the carrier, it is a full locker, not a lunchbox locker. All selectable lockers that I am aware of are full lockers, as the entire differential is replaced. (LSDs also replace the entire differential).

On the other hand, "lunch box" lockers only replace part of the differential. The carrier is not replaced. The EZ Locker and LockRight Locker are examples of lunchbox automtic lockers. The Detroit Locker is an axample of a non-lunchbox automtic lockers.

When lunchbox lockers are installed, they depend on the strength of the original differential carrier and other OEM differential parts for their ultimate strength. Non-lunchbox lockers are built with carriers that have increased strength designed into them. So it is generally accepted that lunchbox lockers are not as strong as full lockers. But lunchbox lockers, because they have less parts, are considerably cheaper than full lockers. They are also usually easier to install, since the R&P pre-loads don't have to be set up again.

Whether a lunchbox locker locker will be strong enough for your particular purposes is determined by, among other things: (1) The strength of the OEM differential carrier and internal parts; (2) The torque applied to the differential; (3) The size tires ddriven by that axle; and, probably most importantly (4) the driving habis of the driver. My CJ7 has lunchbox lockers in both axles, and I run 4.56 gears and 35" tires, and the engine is a warmed-up AMC 360 V8. Even in some hairy situations, I have never had a locker of axle shaft failure. But, then, I'm a believer in taking the best approach to an obsacle and then easing the Jeep over it, rather than the brute force technique.

If you're going to do a lot of serious four wheeling, especially if you have a heavy right foot, you'd do best to not use lunchbox lockers. Actually, in such situations, dual selectable lockers would probably be best. But they're a lot more expensive. For example, the locker parts for the LockRight lockers in both of my axles cost under $700. A pari of detroit lockers would probabl cost twice that. And a pair of ARB lockers, with pump, would probably cost between #1600 and $1800.

With a transfer case like mine (a Dana 300) I have the option of putting twin shifters on it. Meaning that I can engage the front and rear axles seperately. This is used mainly for tight turns up a climb, or tight turns in general. By putting the rear axle into neutral, only the front tires will be turning under power, allowing for a tighter turning radius...as long as the front axle is not locked...hence why I will be getting a front selectable locker...but I will most likely be getting an ARB front and rear.

EZ Locker (lunchbox) not installed (though it is broken)


EZ Locker installed. The "lunchbox" is a light grey color, and the carrier and ring gear are a darker grey (everything around the locker)


Lunchbox lockers replace the spider gears in a differential. Spider gears are what allow the differetiation of speed and torque transfer between the two wheels.

Here is an ARB locker. It replaces the carrier as well as the spider gears, and is selcetable via air.

BigJim, Sorry, but you're lossing it! "Detroit Truetrac was the first type Limited Slip Differential in the industry" ... totally diferent from a Detroit E-Z Locker, or a Detroit (full) Locker. <img src="/forums/images/graemlins/shame.gif" alt="" />

My bad Fred.. I was think'n bout the ez.. You, as usual, are correct..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />