CHANGE: Beginning on May 11, 1998 (Julian Date 131) all THM 4L60-E transmissions were built with a new design plastic 1-2 Accumulator Piston, and an ovate (oval) wire outer accumulator spring, to replace the previous design aluminum piston and round wire outer accumulator spring, as shown in Figure 1. Like to find obd code scanners for help?
REASON: More cost effective than the aluminum piston.
(1)1-2 ACCUMULATOR PISTON – Now manufactured out of plastic instead of the previous aluminum, which necessitated a dimensional change, as the plastic piston is thicker as shown in Figure 1.
(2)1-2 ACCUMULATOR OUTER SPRING – Now manufactured out of an ovate (oval) wire instead of the previous design round wire, to eliminate coil bind as shown in Figure 1.
The different 1-2 Accumulator Pistons and Outer Springs are not interchangeable. When replacing these parts you must remove the 1-2 Accumulator Assembly and inspect for the presence of either the aluminum or plastic 1-2 accumulator piston.
The plastic piston must use the ovate wire outer spring, and the aluminum piston must use the round wire outer spring to ensure against coil bind and spring breakage.
Refer to “Service Information” below for the proper service package part numbers if replacement is necessary.
1-2 Accum. Piston Service Package, 4L60, (1982-1993 Aluminum) …………………….. 24204495
1-2 Accum. Piston Service Package, 4L60-E, (1994-1997 Aluminum)………………….. 24204496
1-2 Accum. Piston Service Package, 4L60-E, (1998-1999 Plastic) ……………………….. 24214343
Note: All service packages include the proper outer spring. Here recommend the car tool Launch Cresetter .
CHANGE: Beginning in the 1998 model year, General Motors added a new design “Bolt-On” bellhousing that is approximately 1/2″ deeper than the previous design. The best identification is the added bolt hole at the top of the bellhousing, as shown in Figure 1. The new design bellhousing is designed to accommodate a new 300mm torque converter, and in the 1998 model year was used only in the Firebird and Camaro. All other models in 1998 used the 298mm converter which required the bellhousing shown in Figure 2. Currently the 300mm converter is used in many more models.
REASON: To accommodate the new 300mm torque converter.
(1) BELL HOUSING – Now has an added hole at the top of the bellhousing and is approximately 1/2″ deeper to accommodate the new 300mm torque converter (See Figure 1).
(2) PUMP COVER – Now requires a stator shaft that is approximately 1/2″ longer to accommodate the new 300mm torque converter (See Figure 3).
(3) TURBINE SHAFT – Now is longer and has the “O” ring behind the splines, as illustrated in Figure 3, to accommodate the new 300mm torque converter.
None of the parts listed above will interchange with previous design parts and the 300mm torque converter must be used in the models they were intended, and 298mm torque converters must be used in the models they were intended for.
Figure 1: http://goo.gl/QsEff
This style bellhousing and the 300mm torque converter also require a new design turbine shaft and stator shaft that are approximately 1/2″ longer than the 298mm torque conveter models. The hot car tools like VAG K Can Plus 2.0 and AK500+ Key Programmer are also helpful for you to solve the problems.
Figure 2: http://goo.gl/XGHkL
Figure 3: http://goo.gl/AXIFg