"A" and "B" gain valves in Allison^® 1000/2000/2400 units ('00–'09) control activation, release and holding pressures for the five clutches in the unit. When the "A" or "B" gain valves, or their bores wear, the control main pressure and reverse signal pressure can cross leak and equalize, preventing proper clutch control. Additionally, wear can permit Reverse signal pressure to escape to exhaust resulting in runaway trim pressure. These conditons lead to shift issues associated with circuit pressure loss. Sonnax oversized gain valve kit 37000-24K corrects shift concerns associated with circuit pressure loss by replacing the worn OE gain valve in both the "A" and "B" gain bores, restoring OE gain valve response and normal "A" and "B" trim signal pressure.

• Hardcoat anodized aluminum valves combat premature wear
• Oversized "A" gain valve designed to utilize OE "A" gain spring