F 350 4WD Pickup V8-7.3L DSL (1988)
Synchronizer Ring: All Technical Service Bulletins
M/T - ZF Model S5-42 Inspection Information
TRANSMISSION - "ZF MODEL S5-42" - INSPECTION INFORMATION
Article No. 90-2-11
LIGHT TRUCK:
1987-90 F-250, F-350 1988-90 BRONCO, F SUPER DUTY, F-150
ISSUE:
The synchronizer rings in the ZF transmission have a molybdenum coating on the grooved surface. This coating provides a very hard surface
in comparison to brass or bronze style rings. The hard surface causes the surface on the friction taper cone of the gear to show different wear
patterns than those shown in transmissions using brass or bronze rings. In some cases synchronizing system parts, rings and gears may be
replaced in error.
ACTION:
Use the following inspection procedure, in addition to Shop Manual and acceptance standards. This information will help you inspect
various wear patterns and sporadic burnt patches or marks on the friction cone of the gear to determine if replacement is required.
Synchronizer Ring
1. Inspect the internal surface for contact pattern. The contact pattern should be the same on the entire internal circumference of the ring.
Figure 1
2. Check the synchronizer ring for proper reserve, Figure 1.
a. Position the synchronizer ring on the synchronizer body as shown in Figure 1.
b. Insert a feeler gauge and measure the clearance at the two opposite points.
c. If the clearance is less than 0.6 mm (0.024") for the 3rd-4th, 1st-2nd and 5th synchronizer assemblies and 0.4 mm (0.016") for the reserve
synchronizer assemblies, replace the synchronizer ring, synchronizer body or both if required to bring to within specification.
Main Shaft And Input Shaft Gears
1. Inspect the friction taper cone on the gears and check for the following wear patterns.
a. Sporadic slightly burnt patches on otherwise evenly smoothed circumference is acceptable. The patches will appear to be blackish in color and
will vary in degree and surface area depending on the synchronizer ring contact area.
b. Signs of excessive heat will appear to be burnt to a reddish-blue color, mainly on the edges of the cone. This is a result of excessive
overloading, operating failure or perhaps a malfunctioning clutch system.
2. Replace gears showing excessively burnt spots (reddish-blue) on the friction taper cone edges. In this case the selector teeth will be damaged as well.
Refer to the appropriate Light Truck Shop Manual, Section 16-34 for service details.
