OVERHAUL

1972–84 4-Speed Transmission

DISASSEMBLY

The clutch housing, split transmission case, and extension housing are all made of aluminum.

1. Drain the oil.
2. Remove the clutch housing, bearing retainer, release bearing, and release fork.
3. Remove the speedometer shaft sleeve and driven gear.
4. Remove the extension housing.
5. Remove the back-up light switch.
6. Separate the case halves. Do not pry apart.
7. Measure gear backlash. The backlash for all gears should be 0.1–0.2mm (0.0039–0.0079 in.).
8. Remove the countergear set from the right-hand half of the case.
9. Use a magnet to remove the ball from the second countergear bearing.
10. Withdraw the input and the output shafts as a unit.
11. Use a punch to drive the three slotted spring pins out of the shift forks and shift fork shafts.

    NOTE: The slotted pin cannot always be fully removed from the first/second shift fork; however, the shift fork can still be withdrawn. Do not try to force the pin out, as damage to the transmission case could result.

12. Remove the case cover and the three detent balls and springs.
13. Remove the shift fork shafts in the following order: First/second shaft. Pin. Reverse shift fork shaft. Third/fourth shaft. Pin.
14. Measure the thrust clearance of the reverse idler gear. The specified clearance is 0.05–0.50mm (0.0019–0.0197 in.).
15. Remove the idler shaft. Remove the gear and washer.
16. Measure the thrust clearance of the gears on the output shaft:
    • 1st, 2nd, 4th — 0.15–0.25mm (0.0059–0.0098 in.)
    • 3rd — 0.15–0.30mm (0.0059–0.0118 in.)
    • Reverse — 0.20–0.30mm (0.0079–0.0118 in.)
17. Disassemble the components of the output shaft. Replace the front bearing, if it is rough or noisy. Use a drift and a press. Remove the snapring first. For bearing installation, replacement snaprings are available in a range of sizes 2.35–2.60mm (0.0925–0.1023 in.) to obtain minimum axial play between the input shaft and the bearing.

ASSEMBLY

1. Assemble the components of the synchronizer hubs, and the output shaft.
2. Install the rear bushing on the output shaft, being careful to install it in the proper direction.
3. Install the ball into the groove of the bushing and slide the bushing over the shaft.
4. Install the needle roller bearing, reverse gear, the ball and the reverse gear synchronizer hub.
5. Install the following items on the output shaft of the four-speed transmission, in the order indicated: Large-diameter reverse gear spacer. Long spacer. Shims.
6. Install the shims and the nut on the end of the output shaft.

   NOTE: If the original nut is being used, change the number of shims to alter the locking portion of the nut.

7. Check the thrust clearance of each gear.
8. Working from the rear of the output shaft, install 3rd gear, synchronizer, spacer, and 3rd/4th synchronizer hub (should face forward).
9. Select a snapring to obtain a thrust clearance of less than 0.05mm (0.0197 in.) for the 3rd/4th synchronizer hub.
10. Assemble the following from the rear of the output shaft: snapring. Key. Speedometer drive gear. snapring.
11. Check thrust clearance of gears.
12. Install the fork and shaft assembly in the transmission case.
13. Insert the straight pins in the grooves on either side of the third/fourth shift shaft.
14. Assemble the first/second gear shaft and fork.
15. Perform Step 11 for the reverse shift fork shaft.
16. Insert the three detent balls, followed by their springs.
17. Place the cover gasket on the case and install the cover.
18. Use a punch to drive a slotted spring pin into each shift fork to secure it.
19. Assemble the input and output shafts.
20. Install the shift forks into their respective grooves on the input/output shaft assembly.
21. Install the shaft assembly in the right-hand half of the transmission case, so that the snapring is positioned firmly against the front surface of the transmission case.
22. Apply grease to the countergear rear bearing lockball. Insert the ball into the hole in the rear bearing outer race.
23. Place the countergear assembly into the right-hand half of the transmission case. Mate the lockball with the hole in the transmission case. Place the bearing snapring firmly against the front surface of the transmission case.
24. Install the reverse idler gear.
25. Install the washers, so that their protrusions align with the grooves in the transmission case.
26. Install the shaft into the case and through the gears and washers.
27. Align the grooves in the idler shaft with the hole in the shaft boss. Install the retaining bolt and washer into the boss.
28. Apply a light coating of liquid sealer over the joint surfaces of the transmission case halves.

    CAUTION
    Do not apply sealer to the ¹⁄₂ in. hole for the back-up light switch.

29. Align the transmission case locating pins with their holes and assemble the halves of the case.

    NOTE: There are four different bolt lengths, do not install the wrong bolt in the wrong hole.

30. Insert the ball, spring, and washer in the back-up light switch hole. Screw in the switch assembly.
31. Install the gasket and bolt the extension housing to the rear of the transmission.
32. Install the speedometer shaft sleeve and drive gear.
33. Apply grease to the conical springs. Install one spring over the input shaft bearing and the other over the countershaft bearing. Install the spacer over the countershaft bearing spring, after coating the spacer with grease.
34. Install the gasket and the clutch housing.

1976–84 5-Speed Transmission

DISASSEMBLY

1. Pull the release fork outward until the spring clip of the fork releases from the ball pivot.
2. Remove the fork and release bearing.
3. Remove the clutch housing shim and gasket.
4. Remove the gearshift lever retainer and gasket.
5. Remove the spring and steel ball, select lock spindle and spring from the gearshift lever retainer.
6. Remove the extension housing with the control lever end down to the left as far as it will go.
7. Remove the control lever end, key and control rod.
8. Remove the lock plate and speedometer gear.
9. Remove the back-up light switch.
10. Remove the snapring and slide the speedometer drive gear from the mainshaft.
11. Remove the bottom cover and gasket.
12. Remove the shift rod ends.
13. Remove the rear bearing housing.
14. Remove the snapring and remove the mainshaft rear bearing, thrust washer and race.
15. Using the puller, remove the washer and countershaft rear bearing.
16. Remove the counter fifth gear.
17. Remove the intermediate housing.
18. Remove the springs and shift locking balls.
19. Remove the two blind covers and gaskets from the case.
20. Remove the reverse/fifth shift rod, fork and interlock pin.
21. Remove the first/second and third/fourth shift forks, rods and interlock pins.
22. Remove the snapring and slide the washer, fifth gear and synchronizer ring from the mainshaft. Also, remove the steel ball and needle bearing.
23. Lock the rotation of the mainshaft with second and reverse.
24. Remove the locknut and slide the reverse/fifth clutch hub and sleeve assembly, synchronizer ring, reverse gear and needle bearing from the mainshaft.
25. Remove the spacer and counter reverse gear from the countershaft.
26. Remove the reverse idler gear, thrust washers and shaft from the transmission case.
27. Remove the bearing rear cover plate.
28. Remove the snapring from the front end of the countershaft and install Mazda tool number 49 0839 445 synchronizer ring holder or its equivalent between the fourth synchronizer ring and the synchromesh gear on the main driveshaft.
29. Remove the countershaft front bearing.
30. Remove the adjusting shim from the countershaft front bearing bore.
31. Remove the countershaft center bearing outer race.
32. With a special puller and attachment, remove the mainshaft front bearing, thrust washer and inner race along with the adjusting shim from the mainshaft front bearing bore.
33. Remove the snapring, and remove the main driveshaft bearing.
34. Remove the countershaft center bearing inner race with the puller.
35. Separate the input shaft from the mainshaft and remove the input shaft.
36. Remove the synchronizer ring and needle bearing from the input shaft.
37. Remove the mainshaft assembly.
38. Remove the first/second and third/fourth shift forks from the case.
39. Remove the snapring and slide the third/fourth clutch hub and sleeve assembly, synchronizer ring and third gear from the mainshaft.
40. Remove the thrust washer, first gear and needle bearing from the rear of the mainshaft.
41. Press out the needle bearing inner race, synchronizer ring, first and second clutch hub, sleeve assembly, synchronizer ring and second gear from the mainshaft.

ASSEMBLY

1. Install the third/fourth clutch hub into the sleeve, place the three keys into the clutch hub slots and install the springs onto the hub.
2. Assemble the first/second and reverse/fifth clutch hub and sleeve.
3. Install the needle bearing, second gear, synchronizer ring, and first/second clutch assembly on the rear section of the mainshaft.
4. Press on the first gear needle bearing inner race.
5. Install the third gear and synchronizer ring onto the front section of the mainshaft.
6. Install the third/fourth clutch assembly onto the mainshaft.
7. Install the snapring on the mainshaft.
8. Install the needle bearing, synchronizer ring, first gear and thrust washer on the mainshaft.
9. Install the mainshaft assembly.
10. Install the needle bearing on the front end of the mainshaft.
11. Install the first/second and third/fourth shift forks in their respective clutch sleeves.
12. Check the mainshaft bearing end-play. Check the depth of the mainshaft bearing bore in the case. Measure the mainshaft bearing height. The difference indicates the required adjusting shim to give a total end-play of less than 0.1mm (0.0039 in.).
13. Install the synchronizer ring holder tool between the fourth synchronizer ring and the synchromesh gear on the input shaft.
14. Position the shims and mainshaft bearing in the bore and install with a press.
15. Install the input shaft bearing in the same way.
16. Check the countershaft front bearing end-play in the same way as the mainshaft bearing end-play.
17. Install the front bearing snapring.
18. Press the countershaft center bearing into position.
19. Install the bearing cover plate.
20. Install the reverse idler gearshaft, thrust washers and reverse idler gear.
21. Install the counter reverse gear and spacer on the rear end on the countershaft.
22. Install the thrust washer and press the needle bearing inner race of the reverse gear on the mainshaft.
23. Install the needle bearing, reverse gear, synchronizer ring, reverse/fifth clutch assembly and new mainshaft locknut on the mainshaft.
24. Lock the mainshaft with the second and reverse gears. Tighten the locknut.
25. Install the needle bearing, synchronizer ring and fifth gear on the mainshaft.
26. Install the thrust washer, steel ball and snapring on the mainshaft.
27. Check the thrust washer-to-snapring clearance. It should be 0.10–0.30mm (0.0039–0.0118 in.).
28. Install the first/second shift rod through the holes in the case and fork.
29. Install the interlock pin with a special installer and guide.
30. Install the third/fourth shift rod through the holes in the case and fork.
31. Align the holes and install the lockbolts of each shift fork and rod.
32. Install the interlock pin as above.
33. Position the reverse/fifth shift fork on the clutch sleeve and install the shift rod.
34. Tighten the lockbolt.
35. Install the three shift locking balls, springs and cap bolts.
36. Place the third/fourth clutch sleeve in third gear.
37. Check the clearance between the synchronizer key and the exposed edge of the synchronizer ring with a feeler gauge. The gap should be 0.66–2.00mm (0.0259–0.0787 in.). Adjust by varying thrust washers.
38. Install the two blind covers and gaskets.
39. Install the undercover and gasket.
40. Apply a thin coat of sealer to the mating edges and install the intermediate housing on the transmission case. Align the lockbolt holes of the housing and reverse idler gearshaft, install and tighten the lockbolt.
41. Position the counter fifth gear and bearing to the rear end of the countershaft and install with a press.
42. Install the thrust washer and snapring.
43. Check the clearance between the washer and snapring. Clearance should be less than 0.1mm (0.0039 in.).
44. Install the mainshaft rear bearing.
45. Install the thrust washer and snapring.
46. Check the thrust washer-to-snapring clearance. Clearance should be less than 0.15mm (0.0059 in.).
47. Apply a thin coat of sealing agent to the mating surfaces and install the bearing housing on the intermediate housing.
48. Install the shift rod ends on their respective rods.
49. Install the speedometer drive gear and steel ball on the mainshaft. Secure it with a snapring.
50. Install a speedometer driven gear assembly on the extension housing and secure it with the bolt and lock plate.
51. Insert the control rod through the holes from the front side of the extension housing.
52. Align the key and insert the control lever end in the control rod.
53. Install the bolt and tighten it to 20–30 ft. lbs.
54. Install the back-up light switch.
55. Place the gasket on the case and install the extension housing with the control lever end down and as far to the left as it will go.
56. Insert the select lock spindle and spring from the underside of the shift lever retainer.
57. Install the steel ball and spring in alignment with the spindle groove and install the spring cap bolt.
58. Install the gearshift lever retainer and gasket on the extension housing.
59. Check the bearing end-play. Measure the depth of the bearing bore in the housing. Measure the height of the bearing protrusion. The difference indicates the thickness of the shim needed. The end-play should be less than 0.1mm (0.0039 in.).
60. Place the gasket on the front side of the case. Apply lubricant to the lip of the oil seal and install the clutch housing on the case.
61. Install the release bearing and fork on the clutch housing.

1986 4-Speed Transmission

DISASSEMBLY

1. Remove the throwout bearing return spring, throwout bearing, and the release fork.
2. Remove the bearing housing.
3. Remove the input shaft and countershaft snaprings.
4. Remove the floorshift lever retainer, complete with gasket.
5. Unfasten the cap bolt and withdraw the spring, steel ball, select lock pin and spring from the retainer.
6. Remove the extension housing. Turn the control lever as far left as it will go and slide the extension housing off the output shaft.
7. Remove the spring seat and spring from the end of the shift control lever.
8. Loosen the spring cap and withdraw the spring and plunger from their bore.
9. Remove the control rod and boss from the extension housing.
10. Remove the speedometer driven gear. Remove the back-up light switch.
11. Remove the speedometer drive gear.
12. Tap the front ends of the input shaft and countershaft with a plastic hammer; then remove the intermediate housing assembly from the transmission case.
13. Remove the three cap bolts; then withdraw the springs and lockballs.
14. Remove the reverse shift rod, reverse idler gear, and shift lever.
15. Remove the setscrews from all the shift forks and push the shift rods rearward to remove them. Remove the shift forks.
16. Withdraw the reverse shift rod lockball, spring, and interlock pins from the intermediate housing.
17. Remove reverse gear and key from the output shaft.
18. Remove the reverse countergear.
19. Remove the countershaft and output shaft from the intermediate housing.
20. Remove the bearings from the intermediate housing and transmission case.
21. Remove the snapring from the output shaft.
22. Slide the third/fourth clutch hub, sleeve, synchronizer ring, and third gear off the output shaft.
23. Remove the thrust washer, first gear, sleeve, synchronizer ring, and second gear from the rear of the output shaft.

ASSEMBLY

1. Install the third/fourth synchronizer clutch hub on the sleeve. Place the three synchronizer keys in the clutch hub key slots. Install the key springs with their open ends 120°apart.
2. Install third gear and the synchronizer ring on the front of the output shaft. Install the third/fourth clutch hub assembly on the output shaft. Be sure that the larger boss faces the front of the shaft.
3. Secure the gear and synchronizer with the snapring.
4. Perform Step 1 to the first/second synchronizer assembly.
5. Position the synchronizer ring on second gear. Slide second gear on the output shaft so that the synchronizer ring faces the rear of the shaft.
6. Install the first/second clutch hub assembly on the output shaft so that its oil grooves face the front of the shaft. Engage the keys in the notches on the second gear synchronizer ring.
7. Slide the first gear sleeve onto the output shaft. Position the synchronizer ring on first gear. Install the first gear on the output shaft so that the synchronizer ring faces frontward. Rotate the first gear as required to engage the notches in the synchronizer ring with the keys in the clutch hub.
8. Slip the thrust washer on the rear of the output shaft. Install the needle bearing on the front of the output shaft.
9. Install the synchronizer ring on fourth gear and install the input shaft on the front of the output shaft.
10. Press the countershaft rear bearing and shim into the intermediate housing, then press the countershaft into the rear bearing.
11. Keep the thrust washer and first gear from falling off the output shaft by supporting the shaft. Install the output shaft on the intermediate housing. Be sure that each output shaft gear engages with its opposite number on the countershaft.
12. Tap the output shaft bearing and shim into the intermediate housing with a plastic hammer. Install the cover.
13. Install reverse gear on the output shaft and secure it with its key.

    NOTE: The chamfer on the teeth of both the reverse gear and the reverse countergear should face rearward.

14. Install the reverse countergear.
15. Install the lockball and spring into the bore in the intermediate housing. Depress the ball with a screwdriver.
16. Install the reverse shift rod, lever, and idler gear at the same time. Place the reverse shift rod in the neutral position.
17. Align the bores and insert the shift interlock pin.
18. Install the third/fourth shift rod into the intermediate housing and shift bores. Place the shift rod in Neutral.
19. Install the next interlock pin in the bore.
20. Install the first/second shift rod.
21. Install the lockballs and springs in their bores. Install the cap bolt.
22. Install the speedometer drive gear and lockball on the output shaft, and install its snapring.
23. Apply sealer to the mating surfaces of the intermediate housing. Install the intermediate housing in the transmission case.
24. Install the input shaft and countershaft front bearings in the transmission case.
25. Secure the speedometer driven gear.
26. Install the control rod through the holes in the front of the extension housing.
27. Align the key with the keyway and install the yoke on the end of the control rod. Install the yoke lockbolt.
28. Fit the plunger and spring into the extension housing bore and secure with the spring cap.
29. Turn the control rod all the way to the left and install the extension housing on the intermediate housing.
30. Insert the spring and select lockpin inside the gearshift retainer. Align the steel ball and spring with the lockpin slot, and secure it with the spring cap.
31. Install the spring and spring seat in the control rod yoke.
32. Install the gearshift lever retainer over its gasket on the extension housing.
33. Lubricate the lip of the front bearing cover oil seal and secure the cover on the transmission case.
34. Check the clearance between the front bearing cover and bearing. It should be less than 0.15mm (0.0059 in.). If it is not within specifications insert additional adjusting shims. The shims are available in 0.15mm or 0.30mm sizes.
35. Install the throwout bearing, return spring and release fork.

1986 5-Speed Transmission

DISASSEMBLY

1. Remove the throwout bearing return spring, throwout bearing, and the release fork.
2. Remove the bearing housing.
3. Remove the input shaft and countershaft snaprings.
4. Remove the floorshift lever retainer, complete with gasket.
5. Unfasten the cap bolt and withdraw the spring, steel ball, select lock pin and spring from the retainer.
6. Remove the extension housing. Turn the control lever as far left as it will go and slide the extension housing off the output shaft.
7. Remove the spring seat and spring from the end of the shift control lever.
8. Loosen the spring cap and withdraw the spring and plunger from their bore.
9. Remove the control rod and boss from the extension housing.
10. Remove the speedometer driven gear. Remove the back-up light switch.
11. Remove the speedometer drive gear.
12. Tap the front ends of the input shaft and countershaft with a plastic hammer; then remove the intermediate housing assembly from the transmission case.
13. Remove the three cap bolts; then withdraw the springs and lockballs.
14. Remove the reverse shift rod, reverse idler gear, and shift lever.
15. Remove the setscrews from all the shift forks and push the shift rods rearward to remove them. Remove the shift forks.
16. Withdraw the reverse shift rod lockball, spring, and interlock pins from the intermediate housing.
17. Remove reverse gear and key from the output shaft.
18. Remove the reverse countergear.
19. Remove the countershaft and output shaft from the intermediate housing.
20. Remove the bearings from the intermediate housing and transmission case.
21. Remove the snapring from the output shaft.
22. Slide the third/fourth clutch hub, sleeve, synchronizer ring, and third gear off the output shaft.
23. Remove the thrust washer, first gear, sleeve, synchronizer ring, and second gear from the rear of the output shaft.

ASSEMBLY

1. Install the third/fourth synchronizer clutch hub on the sleeve. Place the three synchronizer keys in the clutch hub key slots. Install the key springs with their open ends 120°apart.
2. Install third gear and the synchronizer ring on the front of the output shaft. Install the third/fourth clutch hub assembly on the output shaft. Be sure that the larger boss faces the front of the shaft.
3. Secure the gear and synchronizer with the snapring.
4. Perform Step 1 to the first/second synchronizer assembly.
5. Position the synchronizer ring on second gear. Slide second gear on the output shaft so that the synchronizer ring faces the rear of the shaft.
6. Install the first/second clutch hub assembly on the output shaft so that its oil grooves face the front of the shaft. Engage the keys in the notches on the second gear synchronizer ring.
7. Slide the first gear sleeve onto the output shaft. Position the synchronizer ring on first gear. Install the first gear on the output shaft so that the synchronizer ring faces frontward. Rotate the first gear as required to engage the notches in the synchronizer ring with the keys in the clutch hub.
8. Slip the thrust washer on the rear of the output shaft. Install the needle bearing on the front of the output shaft.
9. Install the synchronizer ring on fourth gear and install the input shaft on the front of the output shaft.
10. Press the countershaft rear bearing and shim into the intermediate housing, then press the countershaft into the rear bearing.
11. Keep the thrust washer and first gear from falling off the output shaft by supporting the shaft. Install the output shaft on the intermediate housing. Be sure that each output shaft gear engages with its opposite number on the countershaft.
12. Tap the output shaft bearing and shim into the intermediate housing with a plastic hammer. Install the cover.
13. Install reverse gear on the output shaft and secure it with its key.

    NOTE: The chamfer on the teeth of both the reverse gear and the reverse countergear should face rearward.

14. Install the reverse countergear.
15. Install the lockball and spring into the bore in the intermediate housing. Depress the ball with a screwdriver.
16. Install the reverse shift rod, lever, and idler gear at the same time. Place the reverse shift rod in the neutral position.
17. Align the bores and insert the shift interlock pin.
18. Install the third/fourth shift rod into the intermediate housing and shift bores. Place the shift rod in Neutral.
19. Install the next interlock pin in the bore.
20. Install the first/second shift rod.
21. Install the lockballs and springs in their bores. Install the cap bolt.
22. Install the speedometer drive gear and lockball on the output shaft, and install its snapring.
23. Apply sealer to the mating surfaces of the intermediate housing. Install the intermediate housing in the transmission case.
24. Install the input shaft and countershaft front bearings in the transmission case.
25. Secure the speedometer driven gear.
26. Install the control rod through the holes in the front of the extension housing.
27. Align the key with the keyway and install the yoke on the end of the control rod. Install the yoke lockbolt.
28. Fit the plunger and spring into the extension housing bore and secure with the spring cap.
29. Turn the control rod all the way to the left and install the extension housing on the intermediate housing.
30. Insert the spring and select lockpin inside the gearshift retainer. Align the steel ball and spring with the lockpin slot, and secure it with the spring cap.
31. Install the spring and spring seat in the control rod yoke.
32. Install the gearshift lever retainer over its gasket on the extension housing.
33. Lubricate the lip of the front bearing cover oil seal and secure the cover on the transmission case.
34. Check the clearance between the front bearing cover and bearing. It should be less than 0.15mm (0.0059 in.). If it is not within specifications insert additional adjusting shims. The shims are available in 0.15mm or 0.30mm sizes.
35. Install the throwout bearing, return spring and release fork.
36. The 5th gear housing can be removed by taking out the retaining bolts. The housing will have to be lightly tapped with a soft-faced hammer. The removal of the housing exposes the 5th/reverse synchronizer assembly, the reverse countergear, the countershaft and mainshaft bearings. The bearings are pulled from the shafts and then the gears can be removed. Assembly is the reverse of disassembly.