BMW Coupes and Sedans 1970-1988 Repair Guide

5-Speed Transmission Overhaul

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See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Cut-away view of a 5-speed transmission



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of a 5-speed synchronizer gear assembly

DISASSEMBLY



See Figure 3

  1. Remove the transmission from the vehicle and mount it on a transmission stand.
  2.  
  3. Drain the gear oil and remove the console.
  4.  
  5. Engage 3rd gear, pull back on the spring sleeve and knock out the dowel pin. Pull off the selector rod.
  6.  
  7. Disconnect the extension bracket and the crossmember (with the rubber mount). Unscrew the reverse light switch.
  8.  
  9. Unfasten the mounting bolts and remove the guide flange.
  10.  

Be careful not to lose any shims when removing the guide flange.

  1. Remove the circlip and slotted washer from around the input shaft.
  2.  
  3. Remove the cover, spring and lockpin.
  4.  
  5. Knock out the guide pin aligning the front case, then unscrew the mounting bolts.
  6.  
  7. Separate the front case from the transmission.
  8.  
  9. Remove the lockplate from the rear of the case.
  10.  
  11. While holding the output flange, remove the collar nut and pull off the output flange.
  12.  
  13. Swing the selector shaft against its left stop and push forward; this will engage 2nd gear.
  14.  
  15. Unscrew the rear mounting bolts, then pull off the rear case.
  16.  


WARNING
Always make sure that 2nd gear is engaged before removing the rear transmission case.

  1. Remove the radial oil seal.
  2.  
  3. Swing down the output shaft and pull 5th gear off the layshaft using a gear puller.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Removal of the bearing inner race assembly

The bearing inner race will be removed with the gear.


WARNING
To avoid damage to 3rd gear when removing 5th gear, make sure that there is always play between 3rd gear and the layshaft. If possible, push up on the output shaft.

  1. Using a puller, remove the bearing inner race from the output shaft.
  2.  
  3. Remove the washer and ball, then pull off 5th gear with the synchromesh ring and needle bearing.
  4.  
  5. Remove the needle bearings from the selector shaft.
  6.  
  7. Knock the centerhold pin out of the selector shaft, pull the shaft backward and remove the selector arm.
  8.  
  9. Engage 2nd gear and knock out the centerhold pin.
  10.  
  11. Pull off and remove the rotary lock on the reversing lever, pull the selector rail forward and out. Take out 2nd gear again.
  12.  
  13. With the selector fork operating sleeve toward the rear, pull the 5th gear selector rod far enough so the centerhold pin can be knocked out.
  14.  
  15. Pull off the sliding sleeve and the 5th gear selector fork. Pull the selector rod forward.
  16.  
  17. Pull the guide sleeve and bearing inner race off of the output shaft.
  18.  
  19. Remove the synchromesh ring. Pull off the reverse gear and needle bearing.
  20.  
  21. Engage 3rd gear, then knock out the pin.
  22.  

Knock the pin onto the tooth of 3rd gear until the selector rod can be pulled out forward. Remove the 3rd/4th gear selector rod.

  1. Pull the output shaft toward the rear far enough so that the bearing inner race can be pulled off. Remove the shim.
  2.  
  3. Pull the input shaft, output shaft, layshaft and 1st/2nd gear selector rod out of the intermediate case.
  4.  
  5. Disconnect the holder and remove the reverse gear.
  6.  
  7. Unscrew the bolt and thrust washer holding the front end of the reverse gear shaft and remove.
  8.  

ASSEMBLY



See Figures 4 and 5

  1. Install the reverse gear and holder.
  2.  

The shouldered collar of the reverse gear faces the holder.

  1. Install the input/output shaft assembly into the intermediate case.
  2.  
  3. Install the output shaft shim. Heat the bearing bushing to about 175°F (79°C) and press onto the shaft.
  4.  
  5. Position the needle bearing and reverse gear and then mount the synchromesh ring.
  6.  
  7. Knock the pin out of the 1st/2nd gear selector rod. Install the 1st/2nd gear selector fork. Push the 1st/2nd gear selector rod in against the spring. Insert the detent ball and while pushing down, push the selector rod in against the stop. Install a new centerhold pin.
  8.  
  9. Install the 3rd/4th gear selector fork and then repeat Step 5.
  10.  
  11. Insert the guide sleeve into the sliding sleeve so the tab on the locking lever aligns with the opening in the sliding sleeve. Push the balls in far enough so that the guide sleeve slides into the sliding sleeve.
  12.  

The shouldered end of the sliding sleeve must be opposite the centering pin.

  1. Install the guide sleeve so that the centering pin faces 5th gear.
  2.  
  3. Install the 5th/reverse gear selector fork. Insert the locking ball and push the selector rod in against the spring. Insert the detent ball and while pushing down, turn the selector rod while pushing in so that the openings are opposite the detent balls.
  4.  
  5. Push the selector rod in far enough so that a new centerhold pin can be pressed in. Push the rod and guide sleeve in against the stop.
  6.  
  7. Install the reverse lever with the smooth sides facing down.
  8.  
  9. Install the selector rail, push on the rotary lock and then press in a new pin.
  10.  
  11. Place a small rod in the centering pin, heat the bearing bushing to 175°F (79°C) and then press it onto the output shaft.
  12.  



Click image to see an enlarged view

Fig. Fig. 4: A reference line can be helpful to install the bearing assembly



Click image to see an enlarged view

Fig. Fig. 5: Exploded view of 5-speed gear assembly

  1. Install the needle bearing, synchromesh ring and 5th gear.
  2.  
  3. Mount the transmission on a press and lubricate the contact surface on the layshaft with oil. Heat the 5th gear to 300°F (149°C), then mount it on the layshaft and press it on.
  4.  

Lift and turn 5th gear until the teeth mesh.

  1. Knock the bearing inner race onto the layshaft so that the collar faces the gear.
  2.  
  3. Insert the ball with grease and press on the washer.
  4.  
  5. Heat the ball bearing inner race to 175°F (79°C) and then press it onto the output shaft.
  6.  

The opening in the inner race (rotary lock) must engage with the ball in the output shaft. Make a reference line to facilitate installation of the bearing race.

  1. Install the selector shaft while pushing on the selector arm with the long arm facing the 3rd/4th gear selector rod. Install a new centerhold pin.
  2.  

The stop on the selector shaft must face the selector rail.

  1. Hold the 4 needles on the selector shaft with grease.
  2.  
  3. Swing up the output shaft so that 2nd gear is engaged. Slide the 5th/reverse gear selector rod in until the opening is aligned with the end of the 1st/2nd gear selector rod.
  4.  
  5. Clean the sealing surfaces of the rear and intermediate cases thoroughly and then apply Loctite® or equivalent.
  6.  

The lockpin must move easily and touch bottom.

  1. Hold the needles with grease. Position the rear transmission case making sure that the spring of the selector arm engages the lever.
  2.  
  3. Using a pick or other suitable tool, and push the lockpin into the opening of the 1st/2nd gear selector rod.
  4.  
  5. Hold down the rear transmission case and then press on the bearing inner race.
  6.  
  7. Install the spacer over the output shaft, then press the radial oil seal.
  8.  
  9. Clean the sealing surfaces of the front and intermediate cases, coat with Loctite® or other suitable thread lock compound and attach the front case.
  10.  
  11. Install the reverse light switch and the lockpin.
  12.  
  13. Heat the bearing inner race to 175°F (79°C), pull out the input shaft and press on the bearing race.
  14.  
  15. Install the slotted washer and circlip on the input shaft.
  16.  

Free-play between the washer and circlip should be 0-0.003 inches (0-0.09mm). Adjustment is made with different thickness circlips.

  1. Check that the grooved ball bearing free-play between the layshaft and the guide flange is 0.3 inches (7.8mm) for the input shaft, and 0.1 inches (4.3mm) for the layshaft.
  2.  
  3. Position the shims and install the guide flange.
  4.  
  5. Installation of the remaining components is in the reverse order of removal.
  6.  

 
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