INTRODUCTION
GENERAL MOTORS

6T30/6T40/6T45/6T50 TRANSMISSION

AUTOMATIC TRANSMISSION SERVICE GROUP

18635 S.W. 107 AVENUE
CUTLER BAY, FLORIDA 33157

(305) 670-4161 1
No part of any ATSG publication may be reproduced, stored in any retrieval system or transmitted in any form or
by any means, including but not limited to electronic, mechanical, photocopying, recording or otherwise,
without written permission of Automatic Transmission Service Group. This includes all text illustrations,
tables and charts.

The information and part numbers contained in this booklet have
been carefully compiled from industry sources known for their
reliability, but ATSG does not guarantee its accuracy.

Copyright © ATSG 2016

1st Printing
September, 2016

RICK SONS
TECHNICAL CONSULTANT
ED KRUSE
TECHNICAL CONSULTANT

WAYNE COLONNA
PRESIDENT
PETER LUBAN
TECHNICAL SUPERVISOR

GREGORY LIPNICK
TECHNICAL CONSULTANT

JON GLATSTEIN
TECHNICAL CONSULTANT

JERRY GOTT
TECHNICAL CONSULTANT

GREG CATANZARO
TECHNICAL CONSULTANT
GERALD CAMPBELL
TECHNICAL CONSULTANT

"Portions of materials contained herein have been reprinted under
license from General Motors Corp, Service & Parts Operations

License Agreement Number 0510718"

The Hydra-matic 6T30/40/45/50 (6 Speed) is a fully automatic, six speed, front wheel drive, electronically
controlled transmission that features clutch to clutch shifting. It is also all-wheel drive capable. It was first
introduced in the 2007 Chevy Captiva followed by the Malibu in 2008 and quicky spread to the compact, mid-size,
small crossover vehicle line, as shown in Figure 1. The 6T40 is also found in hybrid applications. At the start of
production for the 2012 model year Generation 2 was introduced which is currently used in all platforms using the
6T family of transmissions. This series of transmissions is also known as the GF6.
It consists primarily of a four element torque converter, three planetary gear sets, five clutch packs, one mechanical
one-way clutch and a hydraulic pressurization and control system. Three planetary gear sets provide the six forward
gear ratios and reverse. Changing gear ratios is fully automatic and is accomplished through the use of a
Transmission Control Module (TCM), that is located within the transmission. The TCM receives and monitors
various electronic sensor inputs, and uses this information to shift the transmission at the optimum time. The TCM
commands shift solenoids and Clutch Pressure Control (CPC) solenoids within the transmission to control shift
timing. The TCM controls shift feel through the CPC solenoids. The TCM also controls the apply and release of the
torque converter clutch which allows the engine to deliver the maximum fuel efficiency without sacrificing vehicle
performance. This manual contains the procedures necessary to diagnose, overhaul and/or repair the 6T30/40/45/50
(6 Speed) GEN 1 and GEN 2 transmissions from General Motors and is for use by professional technicians.

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