Thunderbird V6-232 3.8L (1982)
Clutch: Customer Interest
A/T - No 3rd to 4th Gear Upshift or Slipping 4th Gear
Article No. 83-13-10
TRANSMISSION - AUTOMATIC - AOD
-
NO 3-4 UPSHIFT OR SLIPPING 4TH GEAR
FORD
1980-83 FORD, THUNDERBIRD, LTD
LINCOLN-MERCURY 1980-83 MERCURY, COUGAR, LINCOLN, MARK, CONTINENTAL, MARQUIS
LIGHT TRUCKS 1981-83 F-SERIES AND E-SERIES
Customer concerns of a no 3-4 upshift or a slipping 4th gear can result from causes such as: the direct clutch check ball leaking, miscellaneous leakage or
a blocked hydraulic circuit condition, improper torque on the valve body or sticking valves, a leaking governor, the converter damper/hub assembly
malfunctioning.
Replacement of the direct clutch cylinder piston assembly to alleviate check ball leakage has been effective in most instances.
To verify the direct clutch circuit leakage concern, perform the pressure test below as stated previously. Leakage in the direct clutch circuit has been
attributed
most of the time to a leaking check ball in the direct clutch piston. Replacement of the direct clutch piston will alleviate this condition. However, since
other factors can be involved, the following additional checks/verifications are listed to aid you in a complete comprehensive concern diagnosis for
customer symptoms of a no 3-4 shift or a slipping 4th gear.
NOTE:
To alleviate the direct clutch check ball wedging concern in the piston, a star washer replaced the staking operation mid-March, 1983. All
current service parts depot stock have the updated direct clutch piston level.
Preliminary Checks/Information Verify the following steps have been accomplished:
^
Road test the vehicle to verify the customer complaint. A no 3-4 upshift is characterized by staying in 3rd gear. A slipping 4th gear is characterized
by engine cut-loose on the 3-4 upshift and no 4th gear drive capability.
^
Check TV rod and see if bent or sticking.
^
Check TV linkage (could be misadjusted long).
Bent, sticking or misadjusted TV linkage will not properly synchronize with the carburetor lever at the time a 3-4 shift should occur.
^
Check control pressure and throttle pressure to identify that they are within specifications.
The new 3-4 shift valve (refer to TSB 83-10-11) changes the 3-4 shift pattern. The shift will occur at a higher mph.
Direct Clutch Pressure Test
The direct clutch pressure test outlined below will diagnose a low pressure condition or leakage in the direct clutch circuit. A difference of 15 psi or
more between direct clutch pressure and line pressure (read at the forward clutch pressure tap) will prevent a 3-4 shift.
1.
Attach 0-300 psi pressure gages to the forward clutch pressure tap and to the direct clutch pressure tap. Gage accuracy must be capable of
distinguishing a 15 psi difference. (If this test is done in conjunction with a control pressure test, pressure gages will be attached to all pressure
taps.) Have sufficient flexible hose to read the gages in the vehicle.
CAUTION: PRESSURE GAGES AFFECT THE SHIFT QUALITY OF THE TRANSMISSION. CARE SHOULD BE TAKEN NOT TO
ACCELERATE OR DECELERATE RAPIDLY. POSSIBLE TRANSMISSION FAILURE COULD RESULT.
2.
Drive the vehicle. When pressure is applied to the direct clutch, note the difference between the line pressure read at forward clutch pressure tap
and the direct clutch pressure.
3.
If the difference in pressures is less than 15 psi, the direct clutch circuit is OK.
4.
If the difference is greater than 15 psi, there could be a leak in the direct clutch pressure circuit. (Proceed to the No 3-4 Upshift With Direct Clutch
Pressure Greater Than 15 PSI Diagnostic Procedure). If the difference does exceed 15 psi, the gages on line pressure and direct clutch pressure
can be switched to confirm that gage calibration difference is not the cause. (Proceed to the No 3-4 Upshift With Direct Clutch Pressure Less Than
15 PSI Diagnostic Procedure or to the Slipping 4th Gear Diagnostic Procedure if applicable).
No 3-4 Upshift With Direct Clutch Pressure Greater Than 15 PSI (Indicates Linkage) Diagnostic Procedure
NOTE:
Direct clutch plates burnt will help to confirm leakage in the direct clutch circuit. Replacing only the plates and not finding the cause could
