M/T - T19 Disengagement From Gear

84ford3

Article No. 84-23-10

TRANSMISSION - T-19 - DISENGAGEMENT FROM GEAR

LIGHT TRUCKS 1983/84 F250/350

Gear disengagement may occur for many reasons. This TSB article will identify causal factors and provide servicing guidelines.

1. Evaluate vehicle to verify disengagement. Determine in which mode (Drive, Coast, Float) the disengagement is occurring.

a. Drive (accelerate) mode is when engine is under heavy load - the shifter should be difficult to pull out of third gear.
b. Coast (decelerate) mode is with the clutch engaged and no load on the engine - it should be difficult to pull the shifter out of third gear in this mode at a vehicle speed over 40 MPH.
c. Float (no load) mode is the condition between drive and coast - the lever should not fall out of gear on its own.

2. Perform in-chassis diagnosis and service.

FIGURE 6:

FIGURE 7:

a. Remove shift lever boot and examine isolator pad for a shift lever interference condition. If an interference is exhibited, cut away the pad as required to obtain a 0.5 inch clearance to the shift lever in all gears.
b. Remove the transmission shift tower and perform the following (Figures 6 and 7):
Check each shift rail for slight (1/16 in.) overtravel. If no overtravel exists, change the shift rail.

Change the 1/2 and 3/4 shift rail detent springs from the green spring to the stronger yellow spring.

During the disassembly of the gear shift housing procedure, inspect the bored holes of the gear shift rail detent balls and springs in the shift housing. Verify that the detent springs and balls are not binding up inside the holes due to chips or an undersized hole. If necessary, remove chips and/or re-drill hole to size: 0.379/0.376 inch (3/8 inch) diameter.
c. Inspect transmission gears and synchronizers.

FIGURE 9:

1. Drive Mode disengagement (Refer to Figure 9).
I. Check for a missing snap ring (should be accompanied by excessive in-cab shift lever movement and excessive end play).

FIGURE 8:

II. Check for presence of back taper (Figure 8, View "Y") on the 1st, 2nd and 4th gear clutching teeth, (the teeth that mate with the synchronizer sleeve). If clutching teeth do not have back taper, replace synchronizer assembly (-7124-).
III. Check for end play in each mainshaft gear with dial indicator. Replace any gear whose end play exceeds .030 inch.

FIGURE 9:

2. Coast Mode disengagement (Refer to Figure 9).

I. Check for a missing selective snap ring - Figure 9. II. Verify the spline "side-trim" (Figure 8, View "Z") on the 3rd/4th gear synchronizer hub (7109) by moving the 3rd/4th gear synchronizer sleeve to engage the transmission in 3rd gear and applying a reverse load at output shaft while holding the input shaft stationary. If the "side-trim" on the 3rd/4th gear synchronizer hub is to design intent, the transmission will be prevented from disengaging third gear. If third gear disengagement occurs, replace the complete 3rd/4th gear synchronizer assembly (7124).
III. Check for presence of back taper on the 1st, 2nd and 4th gear clutching teeth. If clutching teeth do not have back taper, replace synchronizer assembly (-7124-).

IV. Check for end play in each mainshaft gear with dial indicator. Replace any gear whose end play exceeds .030 inch.

3. Reassemble transmission and redrive vehicle to verify effectiveness of above actions.

4. If gear disengagement still occurs, it is because the synchronizer has been damaged by the repeated gear disengagements. The synchronizer assembly (7124) should be replaced.

PART NUMBER PART NAME CLASS

E4TZ-7234-C Spring, detent (yellow) C
8MTH-7160 Snap Ring .093" C
C8TZ-7160-B Snap Ring .096" C
C8TZ-7160-C Snap Ring .099" C
C8TZ-7160-D Snap Ring .102" C
74113-S Plug, expansion RS
353096-S Plug, expansion S
C1AZ-19590-B Lubricant AG
E3AZ-19562-A RTV A
D8AZ-19554-A Thread Sealer AG
D8DZ-19C547-A Lubricant BG
C8TZ-7242-D Shaft Rail C

OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP7003C84
TIME: In chassis diagnosis & service - 2.2 Hrs. Transmission overhaul in conjunction with inchassis service - 3.3 Hrs. (4x2) 4.0 Hrs. (4x4)
Supplements:
^ Extra time if equipped w/coupling shaft - .2 Hr.
^ Extra time if equipped w/full floor carpet - .7 Hr.
^ Extra time if equipped w/skid plate - .2 Hr. DLR. CODING: Basic Part No. As Applicable
Code: 83