Detroit Truetrac vs. Locker AMX: Which Differential Is Right for Your Truck?
Ever been stuck in the mud, wheels spinning, while your buddy’s truck cruises through like it’s on pavement? If you’re a truck owner, you know traction can make or break your day whether you’re hauling a trailer, hitting the trails, or just navigating a slick road. That’s where differentials like the Detroit Truetrac and Locker AMX come in. As a guy who’s spent years wrenching on trucks and testing them in everything from desert dunes to snowy backroads, I’ve seen how the right diff can transform your rig. But which one’s better for you: the smooth-operating Truetrac or the hardcore Locker AMX?
In this guide, we’ll break down the Detroit Truetrac vs. Locker AMX, comparing their designs, performance, and real-world use. We’ll tackle the questions truck owners ask most, like how they handle off-road, on-road, and towing, and help you pick the one that fits your driving style. Let’s dive in!
What Are Differentials and Why Do They Matter?
Your truck’s differential is the unsung hero that sends power from the engine to the wheels. In tough conditions like mud, snow, or uneven terrain a standard open differential can leave one wheel spinning uselessly while the other sits idle. That’s where traction-adding diffs like the Detroit Truetrac and Locker AMX shine, ensuring both wheels get power when you need it most.
- Detroit Truetrac: A helical-gear limited-slip differential (LSD) that automatically transfers torque to the wheel with more grip. It’s smooth, maintenance-free, and versatile for street and off-road use.
- Locker AMX: A full-locking differential that locks both wheels together for maximum traction, ideal for extreme off-road conditions but less refined for daily driving.
Understanding their differences is key to choosing the right one for your truck, whether you’re towing heavy loads, crawling rocks, or just cruising to work.
Detroit Truetrac: The Smooth Operator
The Detroit Truetrac, made by Eaton, is a helical-gear limited-slip differential that’s been a favorite among truck owners for decades. It’s designed to balance traction and drivability, making it a go-to for folks who want versatility without drama.
How It Works
Under normal driving, the Truetrac acts like an open differential, letting wheels spin at different speeds for smooth cornering. When one wheel loses traction, its helical gears mesh to transfer up to 3.5 times more torque to the wheel with grip, slowing or stopping wheel spin. It’s fully automatic, with no driver input needed, and it’s maintenance-free no special oils or clutch rebuilds required.
Key Features
- Smooth Operation: No clunking or harsh engagement, making it ideal for street driving.
- Durability: Helical gears have no wearable parts, ensuring lifelong performance.
- Versatility: Works in front or rear axles and suits light off-roading, towing, and daily driving.
- Compatibility: Fits many trucks, like Ford F-150s, GM 1/2-tons, and Rams (2011+).
Real-World Performance
I’ve run a Truetrac in a Chevy Silverado for years, and it’s a game-changer on slick trails or snowy roads. It kicks in seamlessly, keeping both wheels pulling without any fuss. Towing a 10,000-pound trailer? It adds stability by limiting wheel spin. Off-road, it handles mud and sand well, though it’s not perfect if one wheel’s fully off the ground braking can help force torque to the grounded wheel.
Locker AMX: The Off-Road Beast
The Locker AMX is a full-locking differential designed for maximum traction in extreme conditions. While less common than Eaton’s Detroit Locker, it’s a robust aftermarket option for truck owners who prioritize off-road prowess over on-road comfort.
How It Works
The Locker AMX locks both wheels together when torque is applied, sending 100% power to both axles for unrelenting traction. It’s typically an automatic locker, engaging under load and unlocking when coasting or cornering, though some versions may be selectable (e.g., air or electric). This makes it a beast for rock crawling or deep mud but can be less predictable on pavement.
Key Features
- Maximum Traction: Locks both wheels for equal power, perfect for extreme off-road scenarios.
- Rugged Design: Built to withstand abuse, ideal for heavy-duty trucks and off-road rigs.
- Application-Specific: Often used in Jeeps, heavy-duty pickups, and off-road vehicles.
Real-World Performance
I’ve seen Locker AMX setups dominate on rocky trails where one wheel’s dangling in the air. It’s like having a spool both wheels turn together, clawing through obstacles. But on the street, it can be a handful. The locking and unlocking can cause tire scrub or clunking noises, especially in tight turns, and it’s not always friendly with ABS or stability control. For towing, it’s overkill unless you’re hauling in rough terrain.
Head-to-Head: Detroit Truetrac vs. Locker AMX
To help you decide, let’s compare these differentials across key factors truck owners care about:
| Feature | Detroit Truetrac | Locker AMX |
| Type | Helical-gear limited-slip differential | Automatic locking differential |
| Traction | Up to 3.5x torque to high-traction wheel | 100% power to both wheels when locked |
| On-Road Behavior | Smooth, quiet, no noticeable engagement | Clunking, tire scrub in turns |
| Off-Road Capability | Great for light trails, mud, snow | Excels in extreme conditions, rock crawling |
| Maintenance | None, uses standard gear oil | May require periodic checks |
| Cost | $500-$800 + install (~$500) | $600-$1,000 + install (~$600-$1,000) |
| Best For | Daily driving, towing, light off-roading | Hardcore off-roading, heavy-duty use |
On-Road Driving
- Truetrac: Feels like a stock diff on pavement smooth, quiet, and compatible with ABS and ESC. Perfect for daily drivers or long highway hauls.
- Locker AMX: Can be jarring, with clunking noises and tire wear in turns. Not ideal for street-heavy trucks, especially in wet or icy conditions.
Off-Road Performance
- Truetrac: Shines in mud, sand, or snow, but struggles if one wheel’s airborne unless you apply brakes.
- Locker AMX: Unstoppable in rocks or deep ruts, delivering power to both wheels regardless of terrain. Best for hardcore off-roaders.
Towing and Hauling
- Truetrac: Improves stability by limiting wheel spin, ideal for towing trailers or carrying heavy loads.
- Locker AMX: Overkill for most towing unless you’re on rough terrain, where its locked traction shines.
Installation and Cost
- Truetrac: Easier to install, often fitting stock carriers. Total cost (part + labor) is around $1,000-$1,300.
- Locker AMX: May require more setup, especially for selectable versions, pushing costs to $1,200-$2,000 with install.
Common Questions Truck Owners Ask
Is the Detroit Truetrac a locker?
No, it’s a limited-slip differential, not a locker. It transfers torque to the wheel with more traction but doesn’t fully lock both wheels like the Locker AMX. This makes it smoother for street use but less aggressive off-road.
Which is better for off-roading?
For extreme off-roading, like rock crawling or deep mud, the Locker AMX is better because it locks both wheels for maximum traction. For lighter trails or mixed use, the Truetrac is more versatile and less intrusive.
Can I use a Locker AMX for daily driving?
It’s not ideal. The Locker AMX’s locking action can cause tire wear, noise, and handling quirks on pavement, especially in turns or slick conditions. The Truetrac is a better choice for daily drivers.
How do they handle snow or ice?
The Truetrac excels in snow, providing smooth traction without upsetting the truck’s balance. The Locker AMX can be unpredictable, as its locked state may cause sliding in low-traction conditions.
What about maintenance?
The Truetrac is maintenance-free, using standard gear oil with no clutch packs to wear out. The Locker AMX may need occasional checks, especially if it’s a selectable locker with air or electric components.
Can I install these myself?
If you’re handy with a wrench, the Truetrac is DIY-friendly with the right tools and a master install kit. The Locker AMX, especially selectable versions, often requires professional setup due to wiring or air lines. Budget $500-$1,000 for pro installation.
Wrapping It Up: Which One’s Right for You?
Choosing between the Detroit Truetrac and Locker AMX depends on how you use your truck:
- Pick the Truetrac if you want a versatile, low-maintenance differential that’s great for daily driving, towing, or light off-roading. It’s smooth, quiet, and perfect for truck owners who split time between pavement and trails.
- Go for the Locker AMX if you’re a hardcore off-roader tackling rocks, deep mud, or extreme terrain. It’s built for maximum traction but sacrifices on-road comfort.
Next Steps: Check your truck’s axle specs (e.g., Dana 44, GM 8.5”) and consult Eaton’s application guide for Truetrac fitment. For Locker AMX, verify compatibility with your axle and whether it’s automatic or selectable. If you’re unsure, hit up a local 4×4 shop or forums like Jeep Gladiator Forum for advice.
Got a trail story or diff question? Drop it in the comments I’d love to hear how you’re putting your truck to work!