Express Transmissions & Auto Service in Chula Vista specializes in automatic and manual transmission rebuilds from its shop at 1137 Broadway, Suite D, on the western Broadway corridor south of Chula Vista Center Mall. Hard-part sourcing for older domestic transmissions — 4L60E, 4R70W, and 48RE units — sometimes pulls from salvage inventories at Import Auto Wrecking when remanufactured components carry back-order lead times. The shop performs full teardown, inspection, and reassembly using OEM-spec friction plates, steels, seals, and Sonnax valve-body upgrades where factory tolerances have shifted with mileage. Transmission diagnostics include line-pressure testing, stall-speed measurement, and scan-tool analysis of shift-solenoid duty cycles to distinguish electronic faults from internal mechanical wear. Pre- and post-rebuild fluid services align with the ATF-change intervals that quick-service centers such as Jiffy Lube handle for routine maintenance flushes. Completed rebuilds undergo a road-test protocol covering all forward gears, torque-converter lockup engagement, and reverse-apply pressure at operating temperature before release.