The steepest first gear ratio of any four-speed automatic (3.06) belongs to the GM 4L60 (700-R4)/4L60-E family of transmissions. The shift from 3.06 ratio (1st Gear) to 1.63 ratio (2nd Gear) is a dramatic RPM drop that causes performance engines to fall out of their power band.

Sonnax 2.84 input carrier kit 77284-K transforms the popular 4L60 series from an OE “wide ratio” 3.06/1.63 to a “close ratio” 2.84/1.55 for game-changing acceleration on the track. This keeps performance engines in the optimal power band while allowing a longer pull in first and second gears, improving consistency and performance. 

Manufactured and engineered for outstanding durability, the carrier's gears are precision-ground to OE standards, thrust washers feature highly wear-resistant PTFE-coated material and the captured bearing is thicker late design. Lube channels direct oil to the pinion pins, and the carrier can be disassembled for inspection and service.

• Keeps engine in power band on 1-2 and 2-3 shifts
• Delivers longer pull in 1st and 2nd Gears
• Six-pinion planet loaded with advanced durability features
• No special tools or machining required