A/T - Driveline Clunk on 4-3 Downshift
NO: 21-18-94GROUP: Transmission
DATE: Sep. 30, 1994
SUBJECT:
4 Speed Automatic Transmission 4-3 Downshift Clunk
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 21-39-93 DATED DEC. 31, 1993 WHICH SHOULD BE NOTED IN YOUR FILES. THE COMPLETE REPAIR PROCESS HAS BEEN CHANGED. A NEW OVERDRIVE CLUTCH PISTON AND SPACER SELECTION PROCESS ARE INCLUDED.
MODELS:
1988 - 1994 (B) (AB) Ram Van/Wagon
1988 - 1993 (D) (AD) Ram Pick Up/Ram Cab & Chassis
1988 - 1994 (N) (AN) Dakota/Dakota Sport/Dakota Cab & Chassis
1993 - 1994 (ZJ) Grand Cherokee
1994 (BR) Ram Pick Up/Ram Cab & Chassis
SYMPTOM/CONDITION:
Driveline clunk or harshness during 4-3 closed throttle coast down downshift (approximately 18-20 MPH).
DIAGNOSIS:
With the overdrive on (light off), operate the vehicle to verify that the clunk occurs at approximately 18-20 MPH while coasting with the throttle closed. Make sure the transmission is in overdrive (4th gear) before starting the coast down. Repeat with the overdrive off (use O/D switch on the instrument panel - light on). Do this procedure several times with overdrive on and then off. If the clunk occurs only when the overdrive is on, proceed to the repair procedure.
If the clunk occurs during both test phases, overdrive on and overdrive off, look for other possible causes such as driveline backlash, shift cable/linkage adjustment or low transmission oil level. Repair as required.
PARTS REQUIRED:
REPAIR PROCEDURE:
This bulletin involves the removal of the overdrive unit and replacement of the overdrive piston and if needed, an overdrive piston thrust plate spacer.
1. Shift transmission into Park. Raise the vehicle.
2. Remove the transmission oil pan, remove gasket, drain oil and reinstall pan.
3. If the overdrive unit has malfunctioned or if fluid is contaminated, remove entire transmission. If diagnosis indicated overdrive clutch or governor problems only, remove the overdrive unit only.
4. Mark propeller shaft universal joint and axle pinion yoke for alignment reference at installation.
5. Disconnect and remove propeller shaft.
6. Support transmission with transmission jack.
7. Remove rear crossmember.
8. Remove vehicle speed sensor and speedometer adapter.
9. Remove bolts attaching overdrive unit to transmission.
CAUTION:
SUPPORT THE OVERDRIVE UNIT WITH A JACK BEFORE MOVING IT REARWARD. THIS IS NECESSARY TO PREVENT DAMAGING THE INTERMEDIATE SHAFT. DO NOT ALLOW THE SHAFT TO SUPPORT THE ENTIRE WEIGHT OF THE OVERDRIVE UNIT.
10. Carefully work the overdrive unit off intermediate shaft. Do not tilt compounder during removal. Keep it as level as possible. Insert alignment tool 6227-2 in splines of planetary gear and overrunning clutch of O.D. unit to prevent splines from rotating out of alignment.
CAUTION:
IF MISALIGNMENT OCCURS, OVERDRIVE UNIT WILL HAVE TO BE DISASSEMBLED IN ORDER TO REALIGN SPLINES.
11. Remove and retain overdrive piston thrust bearing. Bearing may remain on piston or in clutch hub during removal.
12. Place overdrive unit over drain pan. Tilt unit to drain residual fluid from case. Examine fluid for excessive clutch material or metal fragments. If fluid contains these items, overhaul will be necessary.
13. Remove overdrive piston thrust plate spacer. Retain thrust spacer. It is a select fit part and can be reused.
14. Remove intermediate shaft spacer and retain. It is a select fit and can be reused.
15. Remove overdrive piston from retainer. Discard this piston.
16. Install new overdrive piston, P/N 52118599.
17. Place overdrive unit in vertical position and mount unit in vise or in workbench with appropriate size mounting hole cut into it. Be sure unit is facing upward for access to direct clutch hub.
18. Determine correct thickness of intermediate shaft spacer as follows:
A) Insert special tool 6312 through sun gear, planetary gear and into pilot bushing in output shaft. Be sure tool bottoms against planetary shoulder.
B) Position gauge tool 631 1 across face of overdrive case (Figure 1). Then position dial caliper C-4962 over gauge tool.
C) Extend sliding scale of dial caliper downward through gauge tool slot until scale contacts end of gauge alignment tool 6312. Lock scale in place. Remove dial caliper tool and note distance measured (Figure 1).
D) Select proper thickness end play spacer from spacer chart based on distance measured (Figure 2).
E) Remove gauge alignment tool 6312.
19. Determine the correct thickness overdrive piston thrust spacer as follows.
A) Position gauge tool 6311 across face of overdrive case, then position caliper C-4962 over gauge tool (Figure 3).
B) Measure distance to clutch hub thrust bearing seat at four points 90 degrees apart. Average measurements by adding them and dividing by four.
NOTE:
If measurement is found to be above 1.9 inches, the overdrive assembly must be replaced.
C) Select and install required thrust spacer from information in thrust spacer chart (Figure 4).
20. Leave alignment tool 6227-2 in place. Tool will keep planetary and clutch hub splines in alignment until overdrive is ready for installation on transmission.
21. Verify that splines in overdrive planetary gear and overrunning clutch hub are aligned. Carefully slide alignment tool 6227-2 out of overdrive planetary gear and overrunning clutch splines.
22. Install overdrive unit using a new gasket. Do not use any type of sealer to secure gasket. Use petroleum jelly only.
23. Raise overdrive unit and carefully slide it straight onto intermediate shaft. Insert park rod into park lock reaction plug at the same time. Avoid tilting overdrive during installation as this could cause the planetary and clutch hub splines to move out of alignment.
24. Align slip-fit governor tubes and work overdrive unit forward on intermediate shaft until seated against transmission case.
25. Install bolts attaching overdrive unit to transmission unit. Tighten bolts in diagonal pattern to 25 ft.lbs. (34 N-m).
26. Install crossmember.
27. Install speed sensor and speedometer adapter. Be sure to index adapter.
28. Connect speed sensor and overdrive wires.
29. Align and install propeller shaft.
30. Lower vehicle and refill transmission with Mopar ATF Plus, Type 7176 transmission fluid. Mopar Dexron II can be used if ATF Plus is not readily available.
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
Labor Operation No: 21-15-05-92 (2 Wheel Drive Vehicles) 1.8 Hrs.
21-15-05-93 (4 Wheel Drive Vehicles) 2.8 Hrs.
FAILURE CODE: V3 - Clunk