Modifications

NOTE: Observe the following information when conducting transmission assembly procedures and service on transmission 1st gear bushing and adjustment shims.





Mainshaft Modifications and New Circlips
Mainshaft modifications and new circlips have been introduced and in production since transmission part number 1208427-3 (running number 138176), 1208428-1 (running number 104767) and 1208430-7 (running number 134471). These modifications have been done to counteract loose or broken circlips. The new circlips are 1.75 mm thick; original equipment circlips were 1.50 mm thick. To accommodate the thicker circlips, the mainshaft circlip grooves (as shown in the illustration below) were also made wider.

If during transmission assembly, the original circlips show signs of wear, install the new circlip P/N 968700-5 onto the original mainshaft with a narrow groove. In such a case, ensure that the circlips are firmly pressed into position.

Replacement Needle Bearing And Adjustment Shims
To reduce excessive side play in the 1st gear bushings, replace the 1st gear bushing with a needle bearing and install adjustment shims. This repair can only be accomplished on transmission assemblies incorporating a brass ring attached to the rear of the 1st/2nd synchronizer hub, and applies to transmissions with or without a vibration damper. The adjustment shims should be installed beneath the brass ring.





Required Parts, Special Tools And Material
Note the above required parts, special tools and material to perform the repair.

SERVICE PROCEDURE
1. With transmission removed from vehicle, remove mainshaft assembly from transmission.





2. Transmissions with vibration damper: Press off vibration damper.





3. Remove 1st gear and 1st gear synchronizer ring. Check if 1st gear is fitted with a needle bearing. If 1st gear is fined with a bushing, the bushing must be replaced with a needle bearing as described in operations 12 and 13. Also check information regarding Mainshaft modification and new circlips as described above.
4. Check if brass ring is fitted to the synchronizer hub.
- If brass ring is fitted to synchronizer hub, proceed to operation 15.
- If brass ring is not fined to the synchronizer hub, the synchronizer hub must be replaced with a new hub incorporating a brass ring and proceed to operation 5 through 11.

Replacement Of Hub
5. Using counterhold tool P/N 2853 , press off 1st-2nd synchronizer hub and 2nd gear and synchronizer ring.
6. Reinstall 2nd gear.





7. Disassemble synchronizer.





8. Assemble synchronizer. Place synchronizer hub into the operating sleeve.





9. Insert sliding keys (1) and spring rings (2). Lock the sliding keys using the spring rings. Both spring rings should be hooked onto the same key. Engage the first spring ring counterclockwise. Turn the synchronizer over and engage the second spring ring counterclockwise. The spring rings should start in the same key and extend in opposite directions. If the spring ring is bent, the free end of the spring ring must point outward (away from synchronizer hub).





10. Lubricate mainshaft, then install synchronizer.
- Turn hub so that groove for brass ring is facing 1st gear.
- Do not install the brass ring at this time.





11. Check position of synchronizing ring. Using tool P/N 2852, support mainshaft, then install snap ring.

Replacing Bushing With Needle Bearing, 1st Gear





12. Using a press, remove bushing from 1st gear.
- Use tool P/N 5242 (rear axle special; tool) to support shaft assembly when removing bushing.
- Using tool P/N 5080, press bushing off of shaft.
13. Clean all components thoroughly.





14. Install brass ring (1), synchronizer ring (2), needle bearing (3), and 1st gear (4). Install and properly engage snap ring.

Clearance Adjustment





15. Remove thrust washer from rear of 1st gear. The thrust washer is not installed in transmission assemblies incorporating a vibration damper. Use thrust washer, P/N 1220333-7. This washer will be used only to measure clearance. Remove thrust washer before assembling transmission.





16. Position support tool P/N 2853 under 2nd gear. Place mainshaft into a soft jaw vise (do not tighten the vise).
- Firmly push down on mainshaft to press lock ring into hub. Install thrust washer and press into position.
- Using a feeler gauge, measure clearance between thrust washer and gear.
- Minimum allowable clearance should be 0.10 mm.
- The measured clearance should be as close to the specified minimum clearance as possible.
- To adjust the measured clearance, note the following example: Measured clearance is 0.85 mm.
Install two (2) 0.35 mm adjustment shims under the brass ring. Total thickness of the two adjustment shims is 0.70 mm.

Subtract the total thickness of the two adjustment shims from the measured clearance to obtain a reading as close as possible to the specified minimum clearance given above.

0.85 mm (measured clearance) - 0.70 mm (thickness of the two adjustment shims) = 0.15 mm (adjusted measured clearance).
17. Transmissions with vibration damper: Press on vibration damper. Using tool P/N 5294 (small end of tool facing downward), press vibration damper into position.
18. Check to ensure that the washer is properly positioned on mainshaft. This is especially important if washer has been removed and installed. It should not be possible to turn the washer if it is installed properly.
19. Transmission assembly:
- During assembly of transmission, aluminum mating surfaces should be treated with assembly paste prior to bearing and shaft installation.

- On M46 transmissions, refer to "Assembling M46", operations 27 through 66 for assembly procedure and note the following note.

NOTE: On transmissions incorporating aluminum housings, the intermediate shaft should have a 0-0.05 mm measured end play clearance. Excessive preload may contribute to stiff gear shifting. Also, during assembly, the original adjustment shims can be reused.

- On M47 transmissions, refer to "Assembling M47", operations 23 through 84 for assembly procedure and note the following note.

NOTE: During transmission assembly, the original adjustment shims can be reused.

20. Install transmission, then fill using specified fluid.
21. After adding fluid to the transmission, ensure not to crossthread the transmission drain plugs. Torque transmission drain plugs to 27-40 Nm (20-30 ft lb). Do not over tighten the drain plugs. Transmission housing damage may result (applies to aluminum or cast iron transmission housings) if drain plug tightening torque is exceeded.