Gearstar Performance

Custom Transmission Build Team

  • torque converter matching
  • dyno testing
  • transmission installs
  • GM performance automatics
  • Ford performance automatics
  • Mopar performance automatics




Gearstar Performance Transmissions has been hand-building high-performance automatics in Akron, Ohio since 1996. Every unit is assembled start to finish by one builder, matched to the customer's engine, gearing and intended use, then dyno-tested before it ships. The build team writes here about transmission specs, install procedures, torque converter matching and what actually holds up behind real power.

6L80 vs 6L90: Devil's in the Details

6L80 vs 6L90: Devil's in the Details

Gearstar Performance 6 minute read

The 6L80 and 6L90 are two of the most popular rear-wheel transmissions from General Motors. So many things have been discussed about these remarkable...

Ultimate 700R4 Rebuild Kit Guide

Ultimate 700R4 Rebuild Kit Guide

Gearstar Performance 5 minute read

"What 700R4 rebuild kit is right for me?" This is the question of a prospective rebuilder searching for the best 700R4 rebuild kit on the market. The 700R4...

6L90E Transmission Specs and Identification

6L90E Transmission Specs and Identification

Gearstar Performance 6 minute read

The 6L90E is a high-performance component suitable for handling as much as 700 horsepower. This 6-speed automatic transmission built by General Motors...

E4OD Transmission Upgrades for Heavy-Duty Towing and Off-Roading

E4OD Transmission Upgrades for Heavy-Duty Towing and Off-Roading

Gearstar Performance 5 minute read

The E4OD transmission developed by Ford is a heavy-duty unit generally found in the Bronco, E-series vans, Expedition, and F-series trucks. This is a...

4L80 Torque Converter Basics for Reinforcing Speed and Drivability

4L80 Torque Converter Basics for Reinforcing Speed and Drivability

Gearstar Performance 7 minute read

There was a time when drivability, low emissions, and high horsepower were topics of discussion and disputes. Nowadays, auto-shift cars feature speed, fuel...

An Overdrive Transmission Is Awesome, Just Misunderstood

An Overdrive Transmission Is Awesome, Just Misunderstood

Gearstar Performance 6 minute read

When the automatic transmission first appeared on the market in the 1920s, anyone could count the number of gears on just one hand. But today,...

⇠ Previous Next ⇢