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HOMESERVICE MANUALSPONTIAC1990FIREBIRD TRANS AM, 5.0 F, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)TRANSMISSIONMANUAL TRANSOVERHAUL - GM 77 MM 5-SPEEDTRANSMISSION REASSEMBLY
1990 Pontiac Firebird Trans Am, 5.0 F, Standard

Transmission Reassembly

1990 Pontiac Firebird Trans Am, 5.0 F, StandardSECTION Transmission Reassembly
  1. Coat countershaft front bearing bore with Loctite 601. Install front countershaft bearing flush with facing of case using an arbor press.
  2. Coat countershaft tabbed thrust washer with grease and install washer so tab engages depression in case. Tip transmission case on end. Install countershaft in front bearing bore.
  3. Install countershaft rear bearing spacer. Coat countershaft rear bearing with grease. Install bearing using Installer (J-29895) and Sleeve (J-33032). When correctly installed, bearing will extend .125" (3.0 mm) beyond case surface.
  4. Position reverse idler gear in case with shift lever groove facing rear of case. Install reverse idler shaft from rear of case. Install roll pin in idler shaft.
  5. Install assembled mainshaft in case. Install rear mainshaft bearing in case. Install drive gear in case. Engage in 3rd-4th synchronizer sleeve and blocker ring.
  6. Install front bearing race in front bearing cap. DO NOT  install shims in front bearing cap at this time. Temporarily install front bearing cap.
  7. Install 5th gear-reverse shift rail in case. Engage with 5th gear-reverse shift lever. Rotate rail during installation to simplify engagement with lever. Connect spring to front of case.
  8. Position 5th gear shift fork on 5th gear synchronizer assembly. Install synchronizer on countershaft and shift fork on shift rail. Make sure roll pin hole in shift fork and shift rail are aligned.
  9. Support 5th gear shift rail and fork on a block of wood and install roll pin. Install thrust race against 5th gear synchronizer hub and install snap ring.
  10. Install thrust bearing against race on countershaft. Coat both bearing and race with petroleum jelly.
  11. Install lipped thrust race over needle-type thrust bearing. Install plastic funnel into hole in end of countershaft gear.
  12. Temporarily install extension housing and attaching bolts. Turn transmission case on end. Mount a dial indicator on extension housing with stem of indicator on end of mainshaft.
  13. Rotate mainshaft and zero dial indicator. Pull upward on mainshaft until end play is removed and record reading. Shaft bearings require a preload of .001-.005" (.03-.13 mm). To set preload, select a shim pack measuring .001-.005" (.03-.13 mm) greater than recorded dial indicator reading.
  14. Remove front bearing cap and front bearing race. Install necessary shims to obtain preload and reinstall bearing race.
  15. Apply a 1/8" bead of RTV sealant on case-to-front bearing cap mating surface. Install bearing cap aligning marks made during disassembly. Tighten bolts to specification.
  16. Remove extension housing. Move shift forks on transmission cover and synchronizer sleeves inside transmission to the neutral position. Apply a 1/8" bead of RTV sealant on cover mating surface of transmission.
  17. Lower cover onto case while aligning shift forks and synchronizer sleeves. Center cover and install the 2 dowel bolts. Install and tighten remaining bolts.
    NOTE: The offset lever-to-shift rail roll pin hole must be in the vertical position after cover installation.
  18. Apply a 1/8" bead of RTV sealant on extension housing-to-transmission case mating surface. Install extension housing over mainshaft and shift rail to a position where shift rail just enters shift cover opening.
  19. Install detent spring into offset lever and place steel ball in neutral guide plate detent. Position detent lever on steel ball. Apply pressure on offset lever and at the same time seat extension housing against transmission case.
  20. Install and tighten extension housing bolts. Align and install roll pin in offset lever and shift rail. Fill transmission to proper level with recommended lubricant.
RENDER: 1.0x

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

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  • • 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.