Chrysler Full-Size Vans 1967-1988 Repair Guide

Overdrive-4 Overhaul

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See Figures 1 and 2

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Fig. Fig. 1: Exploded view of the Overdrive-4 (A-833) transmission



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Fig. Fig. 2: Component list of the Overdrive-4 (A-833) transmission exploded view

The Overdrive-4 Speed transmission is a four speed unit with all forward gears synchronized. Third gear is direct, while the fourth gear is the overdrive ratio. Lubricant capacity is 7 pints.

DISASSEMBLY



  1. If available, mount transmission in a repair stand.
  2.  
  3. Disconnect gearshift control rods from the shift control levers and the transmission operating levers.
  4.  
  5. Remove the two gearshift control housing mounting bolts.
  6.  
  7. Remove gearshift control housing from the transmission extension housing or mounting bracket (if so equipped).
  8.  
  9. Remove the gearshift control housing mounting bracket bolts, then remove the bracket (if so equipped).
  10.  
  11. Remove back-up light switch (if so equipped).
  12.  
  13. Remove output companion flange nut and washer, if used, then pull the flange from the mainshaft (output shaft).
  14.  
  15. Remove gearshift housing-to-transmission case attaching bolts.
  16.  
  17. With all levers in the neutral detent position, pull housing out and away from the case.
  18.  

If first and second, or third and fourth shift forks remain in engagement with the synchronizer sleeves, move the sleeves and remove forks from the case.

  1. Remove nuts, lock washers and flat washers that hold first/second, and third/fourth speed shift operating levers to the shafts.
  2.  
  3. Disengage shift levers from the flats on the shafts and remove levers. Remove the E-ring on the overdrive four speed.
  4.  

Extension Housing, Mainshaft & Main Drive Pinion

See Figures 3

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Fig. Fig. 3: Reverse idler shaft removal on the Overdrive-4 (A-833) transmission

  1. Remove the bolt and retainer holding the speedometer pinion adapter in the extension housing, then remove the pinion adapter.
  2.  
  3. Remove the bolts attaching the extension housing to the transmission case.
  4.  
  5. Rotate the extension housing on the output shaft to expose the rear of the countershaft. Install one bolt to hold the extension in place.
  6.  
  7. Drill a hole in the countershaft extension plug at the front of the case.
  8.  
  9. Reaching through this hole, push the countershaft to the rear to expose the Woodruff key; when exposed, remove it. Push the countershaft forward against the expansion plug, and using a brass drift, tap the countershaft forward until the expansion plug is removed.
  10.  
  11. Using a countershaft arbor, push the countershaft out the rear of the case, but don't let the countershaft washers fall out of position. Lower the cluster gear to the bottom of the transmission case.
  12.  
  13. Remove the bolt and rotate the extension back to the normal position.
  14.  
  15. Remove the drive pinion attaching bolts and slide the retainer and gasket from the pinion shaft, then pry the pinion or seal from the retainer. When installing the new seal, don't nick or scratch the seal bore in the retainer or the surface on which the seal bottoms.
  16.  
  17. Using a brass drift, tap the pinion and bearing assembly forward and remove through the front of the case.
  18.  
  19. Slide the third and overdrive synchronizer sleeve slightly forward, slide the reverse idler gear to the center of its shaft, and tap the extension housing rearward. Slide the housing and mainshaft assembly out and away from the case.
  20.  
  21. Remove the snapring holding the third and overdrive synchronizer clutch gear and sleeve assembly to the mainshaft, then remove the synchronizer assembly.
  22.  
  23. Slide the overdrive gear and stop ring off the mainshaft. Using pair of long nose pliers, compress the snapring holding the mainshaft bearing in the extension housing. With it compressed, pull the mainshaft assembly and bearing out of the extension housing.
  24.  
  25. Remove the snapring holding the mainshaft on the shaft. The bearing is removed by inserting steel plates on the front side of the first speed gear, then pressing the mainshaft through the bearing being careful not to damage the gear teeth.
  26.  
  27. Remove the bearing, retainer ring, first speed gear and stop ring from the shaft.
  28.  
  29. Remove the snapring. Remove the first and second clutch gear and sleeve assembly from the mainshaft.
  30.  
  31. Remove the drive pinion bearing inner snapring, then using an arbor press, remove the bearing. Remove the snapring and bearing rollers from the cavity in the drive pinion.
  32.  
  33. Remove the countershaft gear from the bottom of the case, then remove the arbor, needle bearings, thrust washers and spacers from the center of the countershaft gear.
  34.  
  35. Remove the reverse gearshift lever detent spring retainer, gasket, plug, and detent ball spring from the rear of the case.
  36.  
  37. The reverse idler gear shaft is a tight fit in the case and will have to be pressed out.
  38.  
  39. If there is oil leakage visible around the reverse gearshift lever shaft, push the lever shaft in and remove it from the case. Remove the detent ball from the bottom of the transmission case and remove the shift fork from the shaft and detent plate.
  40.  

ASSEMBLY



Reverse Shaft

Follow the first four steps only if you removed the reverse shaft in the disassembly procedure.

  1. Install a new oil seal O-ring on the lever shaft and coat the shaft with grease; insert it into its bore and install the reverse fork in the lever.
  2.  
  3. Install the reverse detent spring and gasket; insert the ball and spring and install the plug and gasket.
  4.  
  5. Place the reverse idler gear shaft in position in the end of the case and drive it in far enough to position the reverse idler gear on the protruding end of the shaft with the fork slot toward the rear. While doing this, engage the slot with the reverse shift fork.
  6.  
  7. With the reverse idler gear correctly positioned, drive the reverse gear shaft into the case far enough to install the Woodruff key. Drive the shaft in flush with the end of the transmission case. Install the back-up light switch and gasket.
  8.  

Countershaft Gear & Drive Pinion
  1. Coat the inside bore of the countershaft gear with a thin film of grease and install the roller bearing spacer with an arbor, into the gear; center the spacer and arbor.
  2.  
  3. Install the roller bearings and a spacer ring on each end.
  4.  
  5. Replace worn thrust washers; coat the new ones with grease and install them over the arbor with the tang side toward the case boss.
  6.  
  7. Install the countershaft assembly into the case and allow the gear assembly to sit on the bottom of the case so that the thrust washers won't come out of position.
  8.  
  9. Press the drive pinion bearing on the pinion shaft. Make sure the outer snapring groove is toward the front end and the bearing is seated against the shoulder on the gear.
  10.  
  11. Install a new snapring on the shaft to hold the bearing in place; make sure the snapring is seated and that there is minimum end-play. There are several snapring thicknesses available for adjustment.
  12.  
  13. Place the pinion shaft in a soft-jawed vise and install the roller bearings in the cavity of the shaft. Coat them with grease and install the bearing retaining snapring.
  14.  
  15. Install a new oil seal in the bore.
  16.  

Extension Housing Bushing
  1. Remove the yoke seal from the extension housing.
  2.  
  3. Drive out the old bushing and drive in a new one, aligning the oil hole in the bushing with the slot in the housing.
  4.  
  5. Place a new seal in the opening of the extension housing and then drive it into place.
  6.  

Mainshaft
  1. Place a stop ring flat on a bench followed by the clutch gear and sleeve; drop the struts in their slots and snap in a strut spring placing the tang inside one strut. Install the second strut spring tang in a different strut after turning the assembly over.
  2.  
  3. Slide the second speed gear over the mainshaft with the synchronizer cone toward the rear and down against the shoulder on the shaft.
  4.  
  5. Slide the first and second gear synchronizer assembly including stop rings with lugs indexed in the hub slots, over the mainshaft down against the second gear cone and hold it there with a new snapring. Slide the next snapring over the shaft and index the lugs into the clutch hub slots.
  6.  
  7. Slide the first speed gear with the synchronizer cone toward the clutch sleeve just installed over the mainshaft and into position against the clutch sleeve gear.
  8.  
  9. Install the mainshaft bearing retaining ring followed by the mainshaft rear bearing; press the bearing down into position and install a new snapring to secure it. There are several snapring thicknesses available for minimum end-play.
  10.  
  11. Install the partially assembled mainshaft into the extension housing far enough to engage the bearing retaining ring in the slot in the extension housing. Compress the ring with pliers so that the mainshaft ball bearing can move in and bottom against its thrust shoulder in the extension housing. Release the ring and make sure that it is seated.
  12.  
  13. Slide the overdrive gear over the mainshaft with the synchronizer cone toward the front followed by the gear's snapring.
  14.  
  15. Install the third-overdrive gear synchronizer clutch gear assembly on the mainshaft against the overdrive gear. Make sure to index the rear stop ring with the clutch gear struts.
  16.  
  17. Install the snapring and position the front stop ring over the clutch gear again lining up the ring lugs with the struts; coat a new extension gasket with grease and place it in position.
  18.  
  19. Slide the reverse idler gear to the center of its shaft and move the third/overdrive synchronizer as far forward as possible without losing the struts.
  20.  
  21. Insert the mainshaft assembly in the case tilting it as necessary. Place the third/overdrive sleeve in the neutral detent.
  22.  
  23. Rotate the extension on the mainshaft to expose the rear of the countershaft and install one bolt to hold it in position.
  24.  
  25. Install the drive pinion and bearing assembly through the front of the case and position it in the front bore. Install the outer snapring in the bearing groove and tap lightly into place. If it doesn't bottom easily, check to see if a strut, pinion roller or stop ring is out of position.
  26.  
  27. Turn the transmission upside down while holding the countershaft gear to prevent damage. Then lower the countershaft gear assembly into position making sure that the teeth mesh with the drive pinion gear.
  28.  
  29. Start the countershaft into the bore at the rear of the case and push until it is in about halfway; then install the Woodruff key and push it in until it is flush with the rear of the case.
  30.  
  31. Rotate the extension back to normal position and install the bolts; turn the transmission upright and install the drive pinion bearing retainer and gasket. Coat the threads with sealing compound and tighten the attaching bolts to 30 ft. lbs.
  32.  
  33. Install a new expansion plug in its bore.
  34.  

Gearshift Housing & Mechanism
  1. Install the interlock levers on the pivot pin and secure with the E-ring. Install the spring with a pair of pliers.
  2.  
  3. Grease and install new O-ring seals on both shift shafts; grease the housing bores and push the shafts through.
  4.  
  5. Install the operating levers and tighten the retaining nuts to 18 ft. lbs.; make sure the third-overdrive lever points down.
  6.  
  7. Rotate each shift shaft fork bore straight up and install the third/overdrive shift fork in its bore and under both interlock levers.
  8.  
  9. Position both synchronizer sleeves in neutral and place the first and second gear shift fork in the groove of the first and second gear synchronizer sleeve. Slide the reverse idler gear to neutral. Turn the transmission on its right side and place the gearshift housing gasket in place holding it there with grease. Install the reverse detent ball and spring into the case bore.
  10.  
  11. As the shift housing is lowered in place, guide the third-overdrive shift fork into its synchronizer groove then lead the shaft of the first and second shift lever.
  12.  
  13. Raise the interlock lever with a screwdriver to allow the first and second shift fork to slip under the levers. The shift housing will now seat against the case.
  14.  
  15. Install the bolts lightly and shift through all the gears to check for proper operation.
  16.  
  17. The reverse shift lever and the first and second gear shift lever have cam surfaces which mate in reverse position to lock the first and second lever, the fork and synchronizer in the neutral position.
  18.  
  19. To check for proper operation, put the transmission in reverse, and, while turning the input shaft, move the first and second lever in each direction. If it locks up or becomes harder to turn, select a new shift lever size with more or less clearance. If there is too little cam clearance, it will be difficult or impossible to shift into reverse.
  20.  
  21. Grease the reverse shaft, install the operating lever and nut, and install the speedometer drive pinion gear and adapter, making sure the range number is in the straight down position.
  22.  

 
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