Spool Performance ZF 8HP70 / 8HP75 / 8HP76 Billet 300M C-Hub Cog Drive

Spool Performance ZF 8HP70 / 8HP75 / 8HP76 Billet 300M C-Hub Cog Drive

The factory C-hub cog drive in ZF 8HP70, 8HP75, and 8HP76 transmissions is produced from cast steel. While adequate at stock power levels, casting brings inherent weaknesses—porosity, uneven grain structure, and localized stress points—that are exposed as torque output, line pressure, and shift aggression increase. Common failure modes include cog tooth deformation, spline wear, and cracking under shock load.

Spool Performance replaces the factory casting with a fully CNC-machined billet 300M C-Hub Cog Drive, engineered specifically for high-torque and high-RPM applications.

300M is an ultra-high-strength, vacuum-melted alloy steel used in aerospace and motorsports driveline components. Compared to cast steel, billet 300M offers dramatically higher strength, superior fatigue resistance, and consistent material properties throughout the part, ensuring it can survive repeated clutch apply events and hard launches.

Each hub is precision-machined to tight tolerances for accurate cog geometry and even load distribution, resulting in cleaner torque transfer, reduced stress concentration, and improved shift consistency.

For any 8HP70/75/76 build running increased power, upgraded clutches, or elevated line pressure, the Spool Performance Billet 300M C-Hub Cog Drive is a critical reliability upgrade, not an optional one.

• Free US shipping on orders over $250.
• Free pickup at our Dallas shop, usually ready within 24 hours.
• Unused parts can be returned within 30 days. Tunes, opened electronics, merch and installed parts are final sale.
• Want it installed? Book the install at thegbmotors.com.

Full details are on our shipping and returns page.