Allison 1000, A & B Trim Valves & Springs & F-trim Spring. Sonnax #37000-12K
#37000-12K (3 SPRINGS, 2 VALVES), #37000-TL12 (2 TOOLS). Long shift duration promotes premature clutch wear in heavy-duty applications. OEM valve and spring configuration do not allow TCM pressure control strategy to adequately raise clutch pressure and shorten shift durations. This modification alters the trim valves and springs, resulting in a more responsive clutch pressure. #37000-12K (3 SPRINGS, 2 VALVES)
• Firmer and shorter upshifts.
• Firmer TCC engagement.
• Improved engine braking on deceleration.
• Increased clutch torque capacity.
Note: The F trim sleeve, valve and spring illustrated are applicable to ‘04 and earlier valve body casting. All F trim components are different in the later application, identified by the larger high frequency TCC solenoid. A-B trim valve update is applicable to all designs.