The factory 4R70W torque converter was built for smooth daily driving in a mostly stock Mustang or F-150, not for handling a built engine, a power adder, or repeated hard launches. The Circle D Pro Series 4R70 Torque Converter is a fully custom billet converter available in four diameters, giving 1996-2004 Mustang and F-150 owners the ability to match the converter to their exact power level and driving style.
245mm: the go-to for naturally aspirated, nitrous, and centrifugal power. This is the converter Circle D recommends for naturally aspirated, nitrous, or centrifugal supercharged 4R70 equipped Fords. It uses a billet front cover and billet lockup piston in place of the factory stamped components, giving it far more strength than the factory unit while still delivering a strong, responsive launch for these power adder types.
252mm: the most durable and adjustable option for big power. Designed for 800+ horsepower applications, the 252mm is built for big turbo, blower, or nitrous combinations that need serious holding capacity. A CNC machined steel stator gives Circle D the ability to fine tune this converter's behavior to your specific setup, and a mechanical diode one way clutch improves efficiency compared to the factory roller clutch design. Anti-balloon plates on the pump and turbine keep internal components from flexing under extreme cylinder pressure.
258mm: a strong mix of drivability and performance. Built for the 4R70W and 4R75W transmissions, the 258mm strikes a balance between everyday drivability and improved launch characteristics, making it a great option if you want more performance without sacrificing how the car drives around town.
265mm: the strongest option for serious power. The 265mm uses a multi disc clutch pack, making it Circle D's most durable diameter for 4R70 equipped Mustangs and F-150s running big power. It's built to handle serious torque without slipping or generating excess heat, whether you're driving it on the street or running it at the track.
Shared construction across every diameter. All four Pro Series converters are furnace brazed and hand TIG welded rather than stamped and glued like the factory unit, use Torrington style bearings to reduce friction and extend service life, and feature a flanged impeller hub for anti-flex durability. Every converter is hand assembled to exacting tolerances, which is what separates a true Pro Series build from a standard rebuilt or off the shelf converter.
Product Benefits
- Available in 245mm, 252mm, 258mm, and 265mm diameters
- 245mm ideal for N/A, nitrous, or centrifugal power
- 252mm designed for 800+ horsepower
- CNC machined steel stator (252mm)
- Mechanical diode one way clutch (252mm)
- Multi disc clutch pack (265mm)
- Billet front cover and billet piston
- Furnace brazed and hand TIG welded
- Torrington style bearings
- Flanged impeller hub for anti-flex durability
- Hand assembled to exacting tolerances
- Built for 1996-2004 Mustang and F-150
- Custom manufactured in the USA
About Circle D Specialties: Circle D Specialties has been building torque converters since 1976, growing from a Houston auto repair shop into one of the most trusted names in performance transmission technology. Using CFD modeling, SolidWorks design, and 5-axis CNC machining done entirely in-house, Circle D custom tailors converters to match each customer's exact combination. Their converters have powered record setting drag cars, including the Silver Bullet, which set the world record for fastest naturally aspirated S550 Mustang, alongside a wide range of high horsepower street and race builds.
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Product Specifications & Vehicle Fitment
Review the product details and confirm compatibility with your vehicle before ordering.
| Specification | Details |
|---|---|
| Vehicle Fitment | 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 |
