Spool Performance Stage 2 Transmission Kit for Dodge 8HP70 & 8HP75

After over a year of rigorous engineering and validation, Spool Performance proudly introduces the Stage 2 Transmission Upgrade Kit for the Dodge 8HP70 and 8HP75 platforms. Designed to far exceed the limitations of factory components, this kit delivers well over 1200 ft-lbs of torque capacity while retaining excellent drivability and shift quality.

This upgrade lets you hold way more torque than a stock 8hp90 from a hellcat reliably without having to go through the struggles of programming and swapping transmissions and is good for upwards of 1200whp.

Each kit features our in-house–developed FX-RT friction system, billet 7075-T6 heat-treated and hard-anodized C and E hubs, redesigned pressure and apply plates, and increased clutch counts across every clutch pack for unmatched clamping force and thermal stability. This package transforms the 8HP70/75 into a transmission capable of handling the abuse of high-boost HEMI builds, drag launches, and elevated power levels.

Advanced Billet Hub Engineering

The OEM C and E hubs in the 8HP series are made from weak cast A380 aluminum and are well-known failure points in tuned Dodge vehicles. Under high torque, these hubs frequently experience:

• Spline shearing

• Cracking at the locking features

• Steel plates digging into the soft aluminum, causing binding, slip, or total burnout

Key Spool Hub Upgrades

• Material Upgrade:
  Manufactured from aerospace-grade 7075-T6 billet aluminum, offering near-steel strength at a fraction of the weight.

• Treatment:
  Heat-treated and hard-anodized, dramatically improving surface hardness, wear resistance, and long-term spline integrity.

• Design Enhancements:

  • Optimized clutch cooling paths

  • Faster oil evacuation

  • Increased clutch contact area

  • Reduced rotating mass for sharper shift response

These improvements eliminate the weak points of the OEM hubs while significantly enhancing performance under sustained high load.

FX-RT High-Coefficient Frictions + Increased Clutch Counts

Our FX-RT friction technology, originally engineered for the highest-torque Mercedes 9G and BMW 8HP platforms, is now optimized for the Dodge 8HP70/75. These friction materials deliver:

• Considerably higher friction coefficients than OEM

• Superior thermal resistance under repeated high-load shifts

• Stable, consistent engagement without harshness

• Exceptional durability on boosted, nitrous, and high-RPM HEMI builds

Each clutch pack — A, B, C, D, and E — receives increased clutch counts, providing more friction interfaces for greater torque handling and cooler operating temperatures.

This combination of FX-RT materials and added clutch capacity results in a transmission that can confidently hold torque levels well beyond the capability of a stock 8HP70/75.

DIY-Friendly Installation

Transmission building can seem intimidating, so we engineered this kit for true DIY accessibility:

• All clutch packs arrive pre-clearanced and ready to install.

• Custom pressure and apply plates eliminate measurement guesswork.

• Includes extra steel plates for builders who want to fine-tune clutch pack clearance or shift feel.

• No machining or specialty modifications required.

• 100% drop-in compatibility with Dodge 8HP70 and 8HP75 units.

If you can rebuild a modern automatic, you can install this kit confidently.

Features Overview

• FX-RT High-Coefficient Frictions: In-house developed, high-energy material for maximum holding power.

• Billet 7075-T6 Hubs: Heat-treated and hard-anodized for superior strength, rigidity, and wear resistance.

• Increased Clutch Counts: Every clutch pack receives added frictions and steels for enhanced torque capacity.

• Custom Pressure & Apply Plates: Provide optimized clamping force and ideal shift characteristics.

• Pre-Clearanced Clutch Packs: Ready to install, eliminating setup guesswork.

• Extra Steel Plates: Included for optional custom clearance adjustments.

What’s Included

• 7075 Billet E Hub

• E Hub Center Bushing

• 7075 Billet C Hub

• A Clutch: Frictions, Steels, Pressure Plate, Apply Plate

• B Clutch: Frictions, Steels, Pressure Plate, Apply Plate

• C Clutch: Frictions, Steels, Pressure Plate

• D Clutch: Frictions, Steels, Pressure Plate, Apply Plate

• E Clutch: Frictions, Steels, Pressure Plate

• Complete Seal Kit (Gaskets + O-rings)

Recommended Fluid

AMSOIL Signature Series Fuel-Efficient 100% Synthetic ATF (Blue Cap)
Ideal for high-performance 8HP builds requiring superior thermal stability.

Compatibility: Dodge / RAM / Jeep / Chrysler 8HP70 & 8HP75 Platforms

Dodge

• Charger R/T 5.7

• Charger Scat Pack / SRT 392 6.4

• Challenger R/T 5.7

• Challenger Scat Pack / SRT 392 6.4

• Durango R/T 5.7

• Durango SRT / 6.4L

RAM

• Ram 1500 5.7 (DT, 8HP75)

• Ram 1500 3.0 EcoDiesel

• Ram 2500 / 3500 6.4 (8HP75-LCV)

Jeep

• Grand Cherokee 5.7

• Grand Cherokee SRT 6.4

• Grand Cherokee 3.0 EcoDiesel

• Wrangler 392 6.4

• Wagoneer / Grand Wagoneer (8HP75 variants)

Chrysler

• 300C 5.7

• 300 SRT 6.4