6L80, 6L90 (300mm), 6L80, 6L90 (300mm), Multi-Plate Performance Converter

JMBX Performance Converter Kit
Part No. GM-RK-21

For street/strip and towing applications.

View Instructions

GM 6L80 and 6L90 gas-powered applications that use a full-size torque converter often have engine modifications for increased output, towing heavy loads, or both, which can quickly push the stock single-disc converter clutch past its capacity. To add strength and durability to stock converters, Sonnax offers forged front cover GM-CC-13 and piston plate GM-DA-17P.

For customers with more demanding applications, Sonnax offers performance converter kit GM-RK-21. Employing a forged cover, forged piston and three woven carbon friction elements, builders now have a dampered 300mm multi-plate option that delivers significantly increased clutch capacity and durability. By re-using the OE damper with the Sonnax clutch plates (bonded with OE woven carbon friction material), GM-RK-21 ensures optimal TCC apply and release characteristics, as well as slip rates that match OE continuous slip calibrations. Drivability is excellent. This easy-to-build and cost-effective kit includes clear, concise instructions.

While testing this kit, Sonnax found that the pressure needed to keep this multi-plate TCC slipping at the calibrated rate was much less than the pressure needed in a comparable single-disc converter. Because the Sonnax multi-plate clutch needs less pressure, there is less demand placed on transmission electronics and hydraulics. With the GM-RK-21, it’s easy for the transmission to keep the TCC slip within required slip parameters.

Enhanced design features include:

  • OE friction material bonded to each clutch plate
  • Forged components assure rigid apply and reaction surfaces
  • Lathe turned feature on mount pads identifies this kit as a multi-plate
  • Added clutch capacity reduces required lockup pressure
  • Lower operating pressure reduces demand on transmission electronics and hydraulics

The converter sticker codes found on 6L80/90 full-size converters are not always consistent. In particular, the JMDZ code can be found on both gas and diesel types of these converters. Be sure to check the bolt circle diameter and overall converter height to verify the Sonnax kit is designed for your application.

  • Front Cover
  • Clutch Plate with Internal Splines
  • Clutch Plate with External Splines
  • Piston
  • Rivets (8) 2 Extra
  • Transmission Unit: 6L80, 6L90
  • Core: GM 300mm
  • Dampered: Yes
  • Lockup: Multi-Plate
  • Unit Size: 300mm
  • Clutch Material: Woven Carbon
  • Turbine Hub Input Spline Count: 36
  • Bolt Circle Dia.: 11.06"
  • Assembled Height: 6.180"
  • Bolt Count: 3

Where to Buy

  • Existing Customers: Contact your sales representative.
  • New Customers: Fill out the form and a sales representative will contact you.
  • 6L80, 6L90 (300mm), 6L80, 6L90 (300mm), Multi-Plate Performance Converter JMBX Performance Converter Kit GM-RK-21
  • 6L80, 6L90 (300mm), 6L80, 6L90 (300mm), Multi-Plate Performance Converter JMBX Performance Converter Kit GM-RK-21 details
  • 6L80, 6L90 (300mm), 6L80, 6L90 (300mm), Multi-Plate Performance Converter JMBX Performance Converter Kit GM-RK-21 details

Videos

6L80, 6L90 300mm Converter Heavy-Duty Builds Explained

Sonnax Performance Converter Kits

Engineered to Deliver Builds that Last

Designed from the ground up to outperform OE and other aftermarket components, Sonnax has you covered with a full line of performance converter kits for gas and diesel vehicles. Offering the widest variety of options in the aftermarket, these innovative kits deliver customized performance and value.

  • Small/Large Diameter
  • Single-Plate/Multi-Plate/Non-Lockup
  • Dampered/Damperless


Choose the right kit for your rebuild!