1989 Buick Skyhawk Base, 4D Sedan, AutomaticFACTORY OEM SERVICE PROCEDURE

Transaxle Case Cover & Input Unit Assembly

  1. Disconnect manual valve rod from manual valve. Remove remaining transmission case cover mount bolts. Install 2 bolts (12 x 1.75 x 50 mm) into case cover dowel pin holes. See Fig 1 .
  2. Bolts will bottom out on dowel pins and separate case cover from case. DO NOT  pry cover from case. Remove case cover, and lay side with 1-2 accumulator up, as 1-2 accumulator pin may drop out of cover.
  3. Remove 1-2 accumulator spring, piston and center case-to-cover gasket. Remove case cover-to-drive sprocket thrust washer and driven sprocket thrust bearing assembly. Case cover-to-drive sprocket thrust washer may come off with case cover.
  4. Remove and discard turbine shaft "O" ring. Remove drive sprocket, driven sprocket and chain as an assembly. See Figure . Remove drive and driven sprocket-to-support thrust washers. These washers may come off with sprockets.
    Fig 1: Removing Transaxle Case Cover from Case
    G92C12676Courtesy of GENERAL MOTORS CORP.
  5. Using 3/16" drift, remove detent lever-to-manual shaft pin. Remove manual shaft-to-case nail. See Fig 2 . Withdraw manual shaft from case, and lift out manual valve rod and detent lever assembly. Remove park lock actuator rod.
  6. Remove driven sprocket support and thrust washer on direct clutch side. See Fig 2 . Thrust washer may come out with driven sprocket support. Remove intermediate band anchor hole plug and intermediate band assembly.
  7. While lifting input shaft, remove and separate direct and forward clutch assemblies. Remove input internal gear-to-input shaft thrust washer, and remove input internal gear.
  8. Remove input carrier assembly, input carrier-to-input internal gear thrust washer and input carrier-to-input sun gear thrust washer. Remove input sun gear and input drum.
Fig 2: Removing Manual Shaft & Driven Sprocket Support
G92D12677Courtesy of GENERAL MOTORS CORP.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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