Pressure loss, a burnt 2-3-4-6-8 (S4) clutch and poor shift quality are common complaints with GM 8L45 and 8L90 transmissions. These symptoms can be caused by a worn S4 clutch control valve and bore that allows valuable clutch apply fluid pressure to leak, reducing the force needed to apply the clutch. The Sonnax oversized S4 clutch control valve kit 154740-26K has an added scarf-cut seal at the signal apply end and a lengthened inboard spool at the clutch apply end that seals a reconditioned bore and restores proper function.

• Hardcoat anodized aluminum valve combats premature wear
• Lengthened valve spool utilizes unworn bore section to seal apply oil
• Annular grooves help center the valve in the bore to reduce future side-load wear
• Scarf-cut seal prevent leaks at the signal apply end for proper clutch control