Vehicles with Toyota/Lexus U660E and U660F transmissions may exhibit 2nd and 6th Gear shift complaints and burnt B1 clutches. This can be caused by wear at the valve and/or boost valve and sleeve, which leads to improper valve function. Reconditioning the bore and installing the Sonnax oversized B1 apply control valve kit 47740-57K will restore valve function, said the company.

The sleeve is manufactured from highly wear-resistant aluminum and features hardcoat anodized aluminum valves to combat premature wear. The annular grooves help center the valve to reduce side-load wear. The valve is designed to reuse the OE spring.