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Home >> GMC >> 1983 >> Magnavan 6.2 J, 400/M40 >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Overhaul & Testing - 700-R4/4L60 >> Component Disassembly & Reassembly >> Input Clutch & Forward Clutch Hub Assembly >> Reassembly
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Input Clutch & Forward Clutch Hub Assembly: Reassembly

  1. If turbine shaft check valve requires replacement, straighten tangs of retainer and remove check ball. Using No. 4 screw extractor, remove check valve. Remove retainer from shaft by turning.
  2. Position check valve in turbine shaft. Using a 3/8" diameter rod, drive retainer and check valve assembly into shaft. Check valve must be positioned 1/8" below top surface of turbine shaft. Ensure check ball is loose.
  3. For input housing check ball replacement, drive retainer and ball assembly from housing using 1/4" diameter drift. Install NEW check ball assembly using 1/4" drift. Check ball assembly should seat on housing shoulder. Assemble forward clutch sprag assembly.
  4. Install sprag assembly in forward clutch race. Notches located in sprag must face upward. See Fig 1 . Install retainer ring on sprag retainer and race. Retainer ring flange must face away from retainer and race.
    Fig 1: Installing & Checking Clutch Sprag Assembly
    G92F13628Courtesy of GENERAL MOTORS CORP.
  5. Hold outer race in left hand. Support sprag assembly. Install sprag retainer and race in sprag assembly. Rotate retainer and race left. Install remaining retainer ring. Install overrun clutch hub. Install snap ring.
  6. Check sprag operation. Holding forward clutch race, rotate overrun clutch hub. Overrun clutch hub should turn freely clockwise and lock counterclockwise. See Fig 1 . If lock operation is not correct, sprag assembly is installed backward.
  7. Place input clutch housing with turbine shaft downward. Install 3-4 piston seals with lips facing away from hub. Install 3-4 piston in input housing. Rotate and gently push downward. Ensure piston is fully seated. Measure 3-4 clutch apply ring from end of arm to base area that sets against 3-4 piston. Different size apply rings are used.
  8. Install 3-4 clutch apply ring. Install "O" ring in input clutch housing. Install forward clutch housing. Install seals on forward clutch piston with lips facing away from tangs.
  9. Install forward clutch piston in forward clutch housing. Install 3-4 spring on 3-4 clutch apply ring. Install forward clutch assembly on3-4 spring assembly. Align forward clutch piston legs with tangs of 3-4 apply ring. Install Seal Protector (J-29883) on input housing.
  10. Install 3-4 apply ring and forward clutch assembly in input clutch housing. Hold apply ring tangs while installing. DO NOT  allow forward clutch piston to separate from assembly. Ensure assembly is firmly seated.
  11. Install Seal Protector (J-29883) on input housing. Install overrun clutch piston with hub facing upward. Remove seal protector. If fully seated, overrun piston should be 3/16" below top of snap ring groove in input housing hub.
  12. Install spring assembly on overrun piston. Install Spring Compressor (J-23456) and Adapter (J-25018-A) on spring assembly. Compress springs, and install snap ring. Remove spring compressor. Install input housing seal.
    NOTE: Soak clutch plates in ATF before installation. Coat all seals and "O" rings with ATF. Coat thrust washers and bearings with petroleum jelly.
  13. Install 4 overrun clutch plates, starting with steel plate. Align wide notches with case lugs. Install remaining clutch plates, alternating steel and composition plates.
  14. Install bearing assembly on input clutch hub. Bearing inner race must face input housing hub. Ensure bearing is centered. Align clutch plate tabs. Install forward clutch sprag assembly in input housing. Align overrun clutch hub with clutch plates.
  15. Install forward clutch apply plate in input housing. Install waved forward clutch plate. Ensure all plates are aligned with input housing tangs. Starting with steel plate, install clutch plates, alternating steel and composition plates. Install backing plate and retainer ring.
  16. Using 2 feeler gauges, measure clearance between backing plate and retainer ring. Clearance should be .030-.063" (.75-1.60 mm). Install correct amount of clutch plates for model application. See FORWARD CLUTCH PLATE SPECIFICATIONS  . Install backing plate with chamfered side upward. For backing plate thickness, see FORWARD CLUTCH BACKING PLATE SPECIFICATIONS  . Install retainer ring.
    FORWARD CLUTCH PLATE SPECIFICATIONS

    Plate Type Quantity Thickness In. (mm)
    Apply 1 .169 (4.29)
    Waved Steel 1 .070 (1.78)
    Flat Steel 5 .090 (2.29)
    Composition 5 .070 (1.78)
    Backing 1 Selective
    FORWARD CLUTCH BACKING PLATE SPECIFICATIONS

    Identification Thickness In. (mm)
    A .274-.278 (6.96-7.06)
    B .251-.255 (6.38-6.48)
    C .228-.232 (5.79-5.89)
    D .205-.208 (5.20-5.28)
    E .180-.185 (4.57-4.70)
  17. Install steel plate, composition plate and backing plate in reverse order of disassembly. Install clutch plates and backing plate with chamfered side upward. Install retainer ring.
  18. Using feeler gauge, measure clearance between backing plate and first composition plate. Clearance is different depending on transmission model. See 3-4 CLUTCH PLATE SPECIFICATIONS  .
  19. Select proper backing plate to obtain correct clearance. See 3-4 BACKING PLATE SPECIFICATIONS  . Air check all clutches by applying air pressure at feed holes in turbine shaft.
  20. During overrun clutch test, air pressure will blow past forward clutch piston seals and exit out forward clutch feed hole in turbine shaft. Turbine shaft seals require sizing and should be installed just before oil pump installation.
3-4 CLUTCH PLATE SPECIFICATIONS

Plate Type Quantity Thickness In. (mm)
Stepped Apply 1 .183 (4.65)
Flat Steel (1) 1 .070 (1.78)
Flat Steel (2) 5 Or 6 .070 (1.78)
Composition (3) 5 Or 6 .079 (2.01)
Backing 1 Selective
(1) Same spline configuration as apply plate.
(2) 6 plates on FBM, MBM and SAM models.
(3) 5 plates on FBM, MBM and SAM models.
3-4 BACKING PLATE SPECIFICATIONS

Identification Thickness In. (mm)
FBM & SAM Models
5 .251-.259 (6.38-6.58)
6 .218-.226 (5.54-5.74)
All Others
7 .186-.194 (4.72-4.93)
8 .153-.161 (3.89-4.09)
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