Differentials Explained: Open, Limited-Slip, and Locking
Your differential is the most important component you never think about — until a wheel starts spinning uselessly in the air while the other three sit still. Understanding the difference between open, limited-slip, and locking differentials helps you choose the right setup for your driving needs.
Open Differential (Stock on Most Vehicles)
An open differential sends power to the wheel with the least resistance. On pavement, this works fine — the inside wheel spins slower than the outside wheel in turns, and both get adequate power. Off-road or on ice? The wheel with the least traction (sometimes literally in the air) gets ALL the power while the wheel on the ground gets nothing.
Best for: Street driving only. It's fine if you never leave pavement.
Limited-Slip Differential (LSD)
LSDs use clutch packs, gears, or viscous fluid to partially lock the two axle shafts together. When one wheel starts spinning faster than the other, the LSD transfers some torque to the slower (gripped) wheel. It's not 100% lock — it's a bias, typically sending 60-80% of torque to the wheel with traction.
Types:
- Clutch-type (Eaton, Auburn): Uses clutch packs. Wears over time. Needs LSD-specific gear oil additive (friction modifier).
- Gear-type (Torsen, Quaife): Uses helical gears. No clutches to wear. Maintenance-free. But doesn't work if one wheel is completely unloaded (airborne).
- Viscous: Uses shear fluid. Quiet and smooth but weakest lock-up. Common in AWD cars.
Best for: Street performance, light off-road, rain/snow traction, daily drivers who want better traction without full lockers.
Locking Differential
A locker physically locks both axle shafts together so they turn at the same speed regardless of traction. Both wheels get 50% of the torque, always. This is the ultimate off-road traction solution.
Types:
- Selectable (ARB Air Locker, Eaton E-Locker): You choose when to engage. Open on the street, locked on the trail. Best of both worlds. Requires compressor (air locker) or wiring (e-locker).
- Automatic (Detroit Locker, Lock-Right): Always locked, unlocks momentarily in turns. Clicking/banging noise in parking lots. Aggressive on-road behavior. Cheap and bulletproof.
- Spool: Permanently welded/machined solid. Both wheels always turn together. Race/dedicated trail use only — terrible for street driving (tires scrub in turns).
Best for: Serious off-road, rock crawling, trail rigs. Selectable lockers are the gold standard for dual-purpose vehicles.
Which Should You Choose?
| Use Case | Recommendation |
|---|---|
| Daily driver, never off-road | Open is fine |
| Daily + occasional trail | Limited-slip (gear-type preferred) |
| Serious off-road + daily | Selectable locker (ARB/E-Locker) |
| Dedicated trail rig | Auto locker front, selectable or auto rear |
| Rock crawler | Selectable lockers front and rear |
Installation Notes
Differential changes often require regearing at the same time — if you're opening up the diff housing, it makes sense to change gear ratios too (especially if you've gone to larger tires). Budget $800-1,500 per axle for parts + labor on a locker install with regear.
Air lockers require an onboard air system — which also lets you air up tires on the trail. Worth the investment.
Suspension Matters Too
A locker puts more stress on axle shafts, U-joints, and suspension components. Proper limit straps prevent over-extension that can snap axle shafts when a locked wheel drops into a hole. If you're investing in lockers, invest in the supporting hardware too.
🔗 Looking for limit straps? Check out our Made in USA Bull Strap Limit Straps — heat-treated 4130 Chromoly, quad-wrap 7,000 lb nylon, 39 sizes available.