Synchronizers Cleaning and Inspection
WARNING: This page is about a different variant/trim than selected.
- Clean all the parts in a suitable cleaning solvent. Air dry all the parts.
- Inspect the synchronizer sleeves for a sliding fit on the synchronizer hubs.
- Replace the 3rd and 4th gear synchronizer hub that does not require a force fit on the mainshaft splines.
- Inspect the synchronizer hub for wear on the external splines. A stepped effect on the teeth, due to wear, may cause shift conditions.
- Inspect the 3rd and 4th gear synchronizer hub for a force fit on the mainshaft splines.
- Replace a worn hub.
- Correct the cause such as, but not limited to, the following:
- Engine related vibrations
- Driving at a low speed in a high gear
- Defective vibration damper or crankshaft
- Incorrectly set injector pump
- Inspect the inserts and springs for wear or damage.
- Inspect the mainshaft drive gear clutch gear teeth for wear.
- Inspect the input shaft clutch gear teeth for wear.
- Inspect the clutch gear for 4th gear, reverse gear, and overdrive gear wear.
- Inspect the synchronizer sleeve teeth (1) for the following, which may cause shift conditions:
- Grated teeth
- Chipped off teeth
- Blunted teeth
- Inspect the synchronizer sleeve detent stops (2) for wear or for being chipped off.
- Replace the synchronizer assembly if the teeth or stops show the above conditions.
- Inspect the three-piece 1st/2nd synchronizer blocker rings for wear.
- Replace the blocker ring assembly if the middle ring grooves are worn away.
- Inspect all of the synchronizer blocker rings for worn shift teeth.
- Inspect the blocker rings for worn friction material.
- Replace the synchronizer ring assembly if any of the above conditions are present.
- Measure the gap between the vertical faces of the blocking ring teeth and the synchronizer clutch gear as follows:
- Assemble the correct blocker ring to the correct gear.
- Apply pressure to the blocker ring to fully seat the ring.
- Using a feeler gauge, measure between the blocker ring teeth and the teeth on the gear.
- 3rd gear 1.73-0.76 mm (0.068-0.030 in)
- 4th gear 2.10-1.19 mm (0.079-0.047 in)
- Overdrive gear 1.83-1.07 mm (0.072-0.042 in)
- Reverse gear 2.24-1.47 mm (0.088-0.058 in)
- If a NEW blocker ring is used, and the standard clearance cannot be obtained, replace the gear.
IMPORTANT:
The wear of the 1st/2nd speed synchronizers can only be measured correctly while the speed gears are installed on the mainshaft. The synchronizer uses a fixed inner cone. Refer to Mainshaft Disassemble .