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Circle D Specialties billet bolt-together torque converter under a single spotlight
Houston, Texas — Performance Torque Converters

We are Circle D.Performance moves us.

Scroll Houston, TX

Our mission is to make exceptional torque converters while providing unparalleled knowledge and outstanding customer service. We are driven to continually improve and raise the bar with our products, relentlessly pursuing perfection. We are a team, we are family, we are Circle D Specialties. Our performance moves us.

Precision Knowledge Family
500,000+
Converters Built
500HP – 5000HP
Holding Power
10,000+
Combinations
02 / CAPABILITY

From CFD to CNC —
all under one roof.

Our state-of-the-art torque converter technology & manufacturing facility allows us to take purpose-built drag racing torque converters to previously unheard-of levels of performance — and that technology trickles down into our products for the street car enthusiast as well. Everything happens right here in-house at our Houston, Texas facility.

/01

CFD Modeling

Fluid flow is mapped in computational fluid dynamics software before any metal moves.

/02

SolidWorks Design

Every component is modeled and engineered in 3D before it is ever cut.

/03

5-Axis CNC Machining

Billet components, machined in-house to exact tolerances.

/04

Data Analysis

Comprehensive data analysis lets us custom-tailor and perfect each converter to the highest degree.

Exploded view of a Circle D 10R80 Pro Series torque converter — front cover, turbine, stator and clutch pack 10R80 Pro Series — component stack
03 / TECHNOLOGY

Race-bred. Street-proven. Daily driven.

  • Billet components, CNC-machined in-house
  • Hand-assembled, tolerance-checked, signed off by a specialist
  • Multi-stage QC — dimensional, balance, leak & pressure verification
04 / FACILITY

Inside the shop.

CNC machining at the Circle D Specialties facility Facility overview — Houston, TX

From the Tech Desk

  • 4L80 Torque Converter Clutch Drag?
    January 24, 2023

    4L80 Torque Converter Clutch Drag?

    Let's talk about torque converter clutch drag when using a multi disc torque converter in a 4L80E transmission. We see this issue come up from time to time, especially (but not limited to) in 4L80E applications equipped with a transbrake...

    Read now