Differential Repair, Re-Gearing & Locker Installation in Corona, CA

UNITRAX by JBM Offroad — Serving Southern California for over 37 years.

Welcome to JBM Offroad, Corona's premier destination for differential repair and high-performance drivetrain builds. We specialize in ring & pinion installation, gear ratio changes (re-gearing), and locker installation for Jeeps, Trucks, SUVs, and fleet vehicles.

Beyond our drive-in service, we are a regional drivetrain hub. We support local shops and mechanics by rebuilding complete differential assemblies (third members). Simply drop off your unit; we build it to precision specs, and you pick it up ready to bolt in.

Call (951) 372-0200 for a same-day quote.

Professional Drivetrain Services

• Ring & Pinion Installation: Precision setup for quiet operation and long-term durability.
• Re-Gearing / Ratio Changes: Ideal for 35" and 37"+ tire setups, towing, and restoring power.
• Differential Rebuilds: Expert replacement of bearings, seals, wear parts, and complete rebuild service.
• Locker Installation: Traction upgrades from ARB, Eaton, and Yukon for serious off-road capability.
• Limited Slip / Posi Upgrades: Better traction for street, towing, and performance builds.
• Differential Assemblies for Shops: Rebuilds of third members / complete assemblies, ready to install.
• Fleet / Commercial Service: Durable solutions for work vehicles and municipal fleets.

Is Your Differential Failing? Common Warning Signs

If you notice any of the following, your drivetrain requires professional inspection to prevent costly failures:

• Whining or Howling: A high-pitched noise that changes with speed, often indicating worn gears.
• Clunking or Banging: Often heard when shifting gears, suggesting broken teeth or worn spider gears.
• Vibration: Excessive shaking that can signal pinion bearing failure.
• Fluid Leaks: Oil on the driveway usually means failed axle or pinion seals.

The Unitrax Precision Process

Differential work is a "game of thousandths." We ensure your build lasts by performing:

• Precision Pattern Checks: We manually verify gear contact patterns for cool, quiet operation.
• Backlash & Pinion Depth Adjustment: Set to exact manufacturer specs using dial indicators.
• Master Kit Upgrades: We use premium Timken or Koyo bearings in every full rebuild.

Choosing the Right Gear Ratio for Larger Tires

Installing larger tires reduces power and fuel efficiency. Re-gearing restores the balance between engine power and tire size.

• 35" tires: Commonly benefit from ratios like 4.56 or 4.88.
• 37" tires: Often require deeper gears such as 4.88 or 5.13.

Authorized Dealer for Top Brands

We stock and install premium components from: Dana Spicer, AAM, Eaton, Yukon Gear & Axle, Richmond, US Gear, Motive Gear, and ARB.

Work Examples