Product Overview
This is the DOWNLOAD link for the 8L90 TechTran. At the start of production for the 2014 model year the Chevrolet Corvette, Chevrolet Silverado 1500 and GMC Sierra began using the eight speed rear drive 8L90 transmission. Since then the 8L90 has been expanded into not only other Chevrolet and GMC vehicles but a number of Cadillac models as well. In some vehicle applications the lighter duty 8L45 is used when engines of lesser horse power are used. Although the 8L45 is arranged internally the same as the 8L90, there are dimensional differences between various parts as well as one less friction and steel plate in some clutch packs. The torque converter is also smaller in diameter however the electronic control system operates the same as a vehicle equipped with the 8L90. For clarity this manual will address the disassembly and assembly procedures for the 8L90 and is intended for use by the professional technician.The 8L90 transmission is a fully automatic eight speed rear wheel drive transmission that is available in both two and four wheel drive configurations. It features clutch to clutch shifting which provides eight forward and one reverse gear. It also uses a four element lockup torque converter, four planetary gear sets as well as five multiple disc and one mechanical clutch set. The 8L90 utilizes an off axis chain drive pump to maintain fluid volume and operating pressures.The externally located TCM controls the changing of gear ratios through the use of solenoids and also controls transmission line pressure through the use of a variable force motor. The TCM will also control converter clutch operation.The 8L90 has undergone some parts changes from its inception until the present. Many of those changes are indicated in this manual. The transmission in this manual was disassembled and reassembled without all factory tools.