Differential Repair at Johnny's Automotive

Your differential is the gearbox that takes power turning one direction and sends it out to the wheels turning another, while letting the outside wheel spin faster than the inside one through a turn. That's the whole job. It sits in a case full of gear oil, it carries every bit of torque the engine makes, and most owners never think about it until it starts making noise.

Rear wheel drive cars and trucks have one at the back. All wheel drive and four wheel drive vehicles typically have a front and a rear, plus a transfer case or a center unit moving power between them. Front wheel drive cars have the differential built into the transaxle alongside the transmission, so it isn't a separate piece of hardware. If you drive a truck, tow anything, or run four wheel drive, you have parts under there worth paying attention to.

Differentials tend to talk before they fail. A whine that rises and falls with vehicle speed, and not with engine speed or gear, usually points at gear or bearing wear. A howl that only shows up when you lift off the throttle points at how the gears are loading against each other. A clunk when you turn or when you pull away from a stop can be worn spider gears, a limited slip clutch pack, or something looser in the driveline entirely. Diagnosis here is largely about telling those apart, and about ruling out tires and wheel bearings, which imitate a differential noise convincingly.

Two things around here wear this hardware faster than the odometer suggests. Towing loads the gears and bearings hard and drives oil temperature up. Backing a trailer down a boat ramp puts a hot axle housing into the water, and as it cools it can pull moisture past a tired seal. We inspect for leaks, play, and contamination, tell you what the noise actually is, and back the work with our 36 month, 36,000 mile nationwide warranty.