Auburn Limited Slip
Overview: The Auburn Limited Slip uses cone and friction materials to create enough friction to hold the axleshafts together. When enough torque bias is realized between the two shafts, the clutches give and allow differentiation of the shafts. In laymen's terms, it grabs until it can't grab anymore, then it turns.
Street:*****
You'll hardly know you've got an Auburn in the rear of your vehicle unless you make enough power to spin the rear tires-then, just look for the two black patches on the pavement. We never experienced chirping or handling quirks when driving it.
Off-road:***
The Auburn has a good amount of grab, but we found the test unit in our 8.25 Chrysler axle didn't really generate enough traction for heavy rock use with 33s and could be overwhelmed if a tire was lifted in twisties with the vehicle climbing.
We'd call the traction performance middle of the road. It's better than a Trac-Lok by a lot, but not quite as grabby as a Truetrac.
Good: The Auburn's excellent street manners and decent traction off-road make it a good choice for daily drivers and mild wheeling vehicles.
Bad: Requires gear oil with a friction modifier, and some installations require slight modifications to the housing. If you're running 33s or bigger and hit some harder terrain, your off-road performance probably won't be that satisfactory. The unit has wearable parts inside and cannot be rebuilt at home. It must be sent back to the factory for refurbishment, which may be required after 100K miles of normal enthusiast usage.
Detroit Electrac
Overview: The Electrac is essentially a Truetrac geardriven limited slip when disengaged and nearly a spool when engaged. An electric solenoid engages the locker when a switch is flipped from inside the Jeep.
Street:****
See Truetrac listing for more information.
Off-road:****
You can go amazingly far with the unit unlocked. Again, see the Truetrac for more information. When it comes to locking the diff, as long as the unit holds together, it's nearly a spool and delivers traction as such. We deducted a point because of the durability issues.
Good: It provides a limited slip when unlocked for those who may sometimes want more than just an open diff with the security of a locker at their fingertips. It's a versatile unit that's good for front and rear applications.
Bad: Because of the small parts inside, we've had no luck with durability on our 35-inch-tire-shod Wrangler. We wouldn't recommend an Electrac on a regularly abused Jeep with big tires and lots of power because there are just too many Swiss-watch-type small parts to go boom. Also, we don't think we'd trust it to survive an axleshaft breaking when under load.
Power-Lok
Overview: The Power-Lok is a clutch-driven limited slip unit and is considered a stronger, heavy-duty version of the Trac-Lok. Power-Loks are commonly found as the optional limited slip in older Jeeps. New units are produced by Precision Gear.
Street:*****
When worn out, you'll think it's an open diff. But even new, it's hardly noticeable on the street.
Off-road:**
Again, when the Power-Lok is worn out, you'll think it's an open diff. Modulating the brake pedal helps make the Power-Lok come alive and provide impressive slightly-better-than-open-carrier traction. We give them a solid "eh."
Good: Came factory in some M38A1s and other early Jeeps, so you may already have one. They're stronger than most other limited slip cases and can be used in front and rear axles without adverse effects.
Bad: They require gear oil with a friction modifier and have wearable clutches, which can be replaced at home. Not for the extreme and not a replacement for a full locker.