Sonnax 4L60E-LB1 Line Pressure Booster Kit for GM 4L60-E 4L65-E 4L70-E Early Style

The Sonnax 4L60E-LB1 Line Pressure Booster Kit is a precision-engineered upgrade for early-style GM 4L60-E, 4L65-E, and 4L70-E automatic transmissions. This kit delivers crisp, clean shifts without harshness by combining a large-ratio boost valve with a stronger pressure regulator spring for progressive pressure control that adapts to driving conditions.

Key Features:

• Fits early-style pumps with long 1.907" boost valve sleeve
• Pressure regulator spring approximately 10% stronger than OEM
• Large-ratio boost valve provides higher pressure incrementally when needed most
• Delivers modest pressure increase at low RPM with high-end pressure equal to or greater than other aftermarket kits
• Progressive pressure increases as driving conditions become more demanding
• Maintains normal engagements and smooth coastdown shifts at low-end pressures
• Simple drop-in installation with no special tools or reaming required
• Achieves shorter shifts and increased torque capacity without low-speed harshness

This booster kit gives you the best of both worlds—improved clutch holding capacity and shift performance for performance applications, heavy-duty towing, or modified vehicles, while avoiding the excessive shock loads and pump overload common with other aftermarket solutions. Ideal for GM vehicles equipped with 4L60-E, 4L65-E, or 4L70-E transmissions from 1993-2005 with early-style pumps.

Note: For late-style pumps with short 1.810" sleeve, use Sonnax part number 4L60E-LB2.