No one knows transmissions & torque converters like

Sonnax designs, develops and manufactures the highest quality aftermarket automotive products. We are the world’s largest full-line supplier of torque converter parts, and offer transmission and specialty driveline components through a global network of parts distributors.

Featured Products Where to Buy
34200 40k web

4L80-E, 4L85-E

Smart-Tech® Overrun Clutch Valve Kit 34200-40K

Fits units '97-later.

99740 07k


Manual Shaft Kit 99740-07K

Fits Dodge units only.

6l45 6l90 zip

6L45, 6L50, 6L80, 6L90

Zip Kit® 6L45-6L90-ZIP

Fd 90 140g


Impeller Hub FD-90-140G

Gm b 8

6T40/6T45, 236mm

Bushing GM-B-8

For use with bushing style impeller hubs only.

Latest News

October 24, 2018

Governor Meets with New Ownership at Sonnax

Sonnax President Steve Boyer met with Governor Scott and Brattleboro Development Credit Corporation Executive Director Adam Grinold on Tuesday as part of Windham County Capitol for a Day.

“We were honored to welcome Gov. Scott to Sonnax and eager to show him the high-quality products and operations made possible by the entire Sonnax team,” said Sonnax President Steve Boyer. “We are pleased to work with government and business development leaders for the continued growth of our state, regional, and local economies.”

“Our Capitol for a Day initiative is about getting outside Montpelier, so we can listen to and learn from Vermonters around the entire state, and better understand their unique challenges and opportunities,” said Governor Scott. “And as my Administration makes expanding and strengthening Vermont’s workforce a top priority, it was incredibly valuable to hear from BDCC and Sonnax leadership about the workforce needs in the region, and the regional efforts to recruit and train Vermonters for the good jobs available today.”

About Capitol for a Day:
The Governor, along with members of his cabinet and extended cabinet, spend the day in every county, meeting with area constituents, lawmakers, local partners and state employees throughout the day.

The initiative aims to give regional constituencies direct access to Administration leadership, as well as giving Administration officials an opportunity to visit regional businesses, schools, community organizations and municipal offices. The Administration expects to visit each of the state’s 14 counties throughout the summer and fall of 2018.

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September 26, 2018

New 4L60/E Catalog Available Now

Get your free copy of the new GM 4L60/E catalog now! It's jam-packed with:

  • Can’t-miss, performance upgrades for street enthusiast to extreme racing builds
  • Handy build charts for three levels of performance applications – plus HD pickups
  • Tips on how to build the ‘killer’ 4L60/E

If you think that 4L60/E on your bench can’t be faster, tougher, stronger – think again. Thanks to groundbreaking Sonnax upgrades, performance specialists are bringing this veteran tranny roaring back to life with jaw-dropping performance and reliability unimaginable even a decade ago.

Get your free copy here >>


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August 31, 2018

Sonnax Closed on Labor Day

Sonnax will be closed on Monday, September 3, in honor of Labor Day. Wishing you a safe and happy holiday weekend!

View News Archive

Upcoming Events

King-O-Matic/ATSG Seminar & Trade Show

3670 Hurontario St., Mississauga, ON

November 16, 2018, 7:00PM - 10:30PM

Learn More

PRI Show 2018

Indianapolis, IN

December 06, 2018, 9:00AM - 4:00PM

Learn More
See All Events

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Enjoy a rewarding career and relaxing quality of life
in beautiful Southern Vermont.

Recognized as one of the Best Places to Work in Vermont and recipient of the Governor's Worksite Wellness Award, Sonnax is a leading supplier to the automotive aftermarket. We design, manufacture, test and distribute a wide variety of innovative, high quality products used to remanufacture torque converters, rebuild automatic transmissions, upgrade driveshafts and protect the driveline from over-torque damage.

Sonnax is one of the fastest growing companies in the state of Vermont. Our name has become synonymous with exceptional service, cutting-edge designs, technical knowledge and customer dedication. Join an exciting front-line team focused on developing and delivering the best products in the industry, a team whose imagination, hard work and results are rewarded.

Careers at Sonnax