Differentials

Differentials, Ring & Pinion Sets and Diff Covers

The differential is the component that allows the driven wheels to rotate at different speeds when cornering — essential for smooth, controlled operation — while still distributing torque to both wheels. In a performance context, the differential specification significantly affects traction and handling: an open differential sends power to the wheel with least resistance, which is the one most likely to spin under hard acceleration. A limited slip or locking differential maintains traction to both wheels simultaneously, dramatically improving traction on slippery surfaces and under hard acceleration.

Our differential range from Hurst Engineering and Mr. Gasket covers ring and pinion gear sets, differential covers, and related driveline components for popular American V8 applications.

Ring and Pinion Gear Sets — Final Drive Ratio

The ring and pinion gear ratio — the final drive ratio — is one of the most powerful tuning tools available for optimising vehicle performance for a specific application. A numerically higher ratio (3.73:1, 4.10:1) multiplies engine torque more aggressively, providing stronger acceleration at the cost of higher cruising RPM. A numerically lower ratio (2.73:1, 3.08:1) reduces cruise RPM and improves fuel economy but dulls acceleration response. Selecting the right ratio requires knowing the transmission ratios, tyre diameter, target driving conditions, and power characteristics of the specific engine combination.

Differential Covers — Protection and Oil Capacity

Aftermarket differential covers provide increased oil capacity and improved cooling for the differential ring and pinion — beneficial on high-power applications where the differential generates significant heat under sustained hard use. Quality billet and cast aluminium covers provide better protection than factory pressed steel items and in many cases include fill and drain plugs that simplify oil service.