Heavy Duty Sprag Element
Part No. 34658-HD

Sonnax heavy duty sprag element 34658-HD is the ideal upgrade for GM TH400, 4L80-E, 4L85-E intermediate sprags in performance racing transmissions. Designed for Pro Mod-style direct drums, the Sonnax sprag delivers superior durability for any unit that would otherwise run a BorgWarner 27499AM sprag.

Builders often replace the 34-element, intermediate sprag in TH400, 4L80-E series units with the 36-element, OE forward clutch sprag from the stock 4T80-E. Originally manufactured by BorgWarner under part number 27499AM, this component — known as a Pro Mod-style sprag when used in the TH400 and 4L80-E — is no longer available. Sonnax fills the gap with a direct replacement sprag whose precision construction and increased element count withstand greater torque loads and harsher operating conditions than any other option on the market.

• High-strength, 40-element sprag protects against clutch failure under high torque loads and harsh conditions
• Pro Mod-style sprag upgrades TH400, 4L80-E, 4L85-E intermediate and 4T80-E forward sprag locations
• Direct replacement for the discontinued BorgWarner 27499AM sprag