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.

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Enter a Sonnax part number below to view its instructions. For general reaming instructions, click here.

Latest News

June 01, 2022

TCRA Announces Sonnax Credit for Members

The Torque Converter Rebuilder’s Association (TCRA) is pleased to announce that Rebuilder Members in good standing will each receive a $200 credit from Sonnax. The credit can be used towards their existing Sonnax account or towards future purchase.

“I was pleasantly surprised when Sonnax offered this direct award to our Rebuilder Members,” said Mike Cargill, President of TCRA. “TCRA has a variety of benefits we already provide, and this one-time offer from Sonnax is really icing on the cake! Sonnax has always stepped up to support our association and the industry at large, and this is just another example.” 

“Sonnax is the foremost provider of components to torque converter rebuilders,” said Steve Boyer, President of Sonnax. “TCRA quickly suspended the monthly dues for their members when the pandemic first hit, and it inspired us to look for ways to lend a hand as well. With business ramping up beyond pre-COVID levels, we hope this effort helps Rebuilder Members serve their customers in these challenging times.” 

The Torque Converter Rebuilder’s Association is a nonprofit trade association that supports and promotes torque converter rebuilding around the world. TCRA strives for better communication between its members, the torque converter industry in general, and the wider ranging transmission and powertrain industry. Learn more about TCRA at


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February 09, 2022

Top Products - As Voted by You

Every year, Transmission Digest accepts nominations for the top 10 products and tools in the powertrain aftermarket. Readers vote for their favorites to determine the winners. The results are in: we won six top product awards! Thank you all for your trust and support of Sonnax products – we couldn’t have done it without you.

Take a look at the winning products here:


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December 20, 2021

Sonnax Holiday Hours

Heads up! We’re taking a few days off for the holidays to spend treasured time with our families and enjoy the festivities.

Sonnax will be closed:

  • Dec. 24
  • Dec. 27
  • Dec. 31
  • Jan. 3

Thank you for all your support. Wishing you a happy, healthy and prosperous New Year!

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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.

After decades of serving the transmission aftermarket as standalone companies, Sonnax and Rostra Powertrain Controls integrated in 2021 to become a single, transmission-focused organization.

Our 200+ employees proudly serve the automotive aftermarket with the Sonnax and Rostra Powertrain Controls brands, and strive to further the company’s reputation for excellent service, technical knowledge and customer dedication.

Sonnax Transmission Company headquarters is in Bellows Falls, Vermont, with production facilities in Laurinburg, N.C. and technical development centers in California, Georgia, Indiana, Missouri and Wisconsin. Rostra Powertrain Controls’ production facility is in Laurinburg, N.C.

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