GMC 1989 Light Duty Truck, Repair Manual, Page: 809 / 998

7A3-1
SECTION 7A3
180C AUTOMATIC TRANSMISSION
CONTENTS
GENERAL INFORMATION Planetary C a rrie r..................................... ___ 7A3- 6
UNIT REPAIR Third Clutch A ssem bly........................... ___ 7A3- 7
EXTERNAL P A R T S ......................................... . .7A3- 1
Sprag Unit................................................. ___ 7A3- 9
Servo Piston Removal................................. . .7A3- 1
Reverse Clutch P a r ts ............................... ___ 7A3-12
Selector Lever and Electrical Determining Selective Washer
Connector Rem oval................................. . .7A3- 2 Thickness................................................. ___ 7A3-12
Modulator and Detent Valve Converter Housing, Oil Pump and
Assem blies............................................... . .7A3- 3 Reverse C lutch ..................................... ___ 7A3-13
Extension Housing, Speedometer Driven Governor H u b ........................................... ___ 7A3-15
Gear and Governor Assem bly................ . .7A3- 3 Governor Body and Speedometer
INTERNAL PARTS........................................... . .7A3- 3 Drive Gear............................................. ___ 7A3-15
COMPONENT REPAIR AND Extension Housing and Speedometer
TRANSMISSION ASSEMBLY....................... . .7A3- 6
Drive Gear............................................. ___ 7A3-17
C a s e .............................................................. . .7A3- 6 Detent Valve and Modulator..................... ___ 7A3-18
Case Interior................................................. . .7A3- 6 Servo Piston............................................. ___ 7A3-18
Selector Lever and S h a ft........................... 7A3- 6 Control Valve A ssem bly...........................
External Parts...........................................
7A3-19
___ 7A3-22
T R A N SM ISSIO N D IS A S S E M B LY
GENERAL SERVICE IN F O R M A T IO N
• Oil Seal Rings
If any seal rings are damaged, cut, or do not
rotate freely in their grooves, be certain to check
the ring groove for debris, burrs, or damage.
• Thrust washer surfaces
The thrust washers and bearing surfaces may
appear to be polished. This is a normal condition
and should not be considered damage.
• Snap rings
Do not over expand snap rings when removing or
installing.
EXTERN AL PARTS
Clean
Thoroughly clean
transmission.
the exterior of the
Remove or Disconnect
Torque converter
Install or Connect
Tools Required
J-3289-20 Base
J-8763-01 Holding Fixture
1. J-8763-01 onto transmission case.
2. Holding fixture into the base.
Remove or Disconnect
• Drain the transmission fluid through the rear
extension.
|<-+| Remove or Disconnect (Figure 1)
1. Bolts, oil pan and gasket.
2. Bolts, oil strainer and gasket.
3. Manual detent roller and spring assembly.
4. Electrical connections at the governor pressure
switch.
5. Solenoid from transfer plate reinforcement.
6. Solenoid from the solenoid pipes.
7. Solenoid pipes from the valve body and the case.
1.
2 .
3.
4.
5.
Remove or Disconnect (Figure 2)
Governor pressure switch using a 1-1/16 oil
pressure switch socket.
Bolts, transfer plate reinforcement.
Bolts, servo cover, and gasket.
Bolts, valve body, and manual valve link.
Check balls.
Servo P iston Rem oval
|<” »| Remove or Disconnect (Figures 3 and 4)
Tools Required
J-23075 Servo/3rd Clutch Piston Spring
Compressor
1. Install J-23075 with tool offset to the rear case.
2. Compress servo piston.