A/T - A500/A518 Repeat Failures of Overdrive Clutch

90chrysler01

Models

1988-90 B/AB, D/AD, & A/AN Bodies


Subject

Repeat Failures Of Automatic Transmission Overdrive Clutch


Index

TRANSMISSION


Date

January 29, 1990


No.

21-01-90

P-151 (C21-26-9)
BODY CODE LEGEND

B/AB - RAM VAN/WAGON (RWD) D/AD - RAM PICKUP/RAM CAB & CHASSIS/RAMCHARGER (RWD, 4WD) POWER RAM CAB & CHASSIS (4WD)
N/AN - DAKOTA/DAKOTA SPORT/DAKOTA CONVERTIBLE DAKOTA CAB & CHASSIS


THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH THE A500 OR A518 AUTOMATIC TRANSMISSION.

SYMPTOM/CONDITION

Repeated failures of the overdrive clutch.

The A500 and A518 automatic transmissions have a small nylon orifice plug in the overdrive piston retainer. The purpose of this orifice is to bleed line pressure into the cavity in front of the overdrive piston to keep this cavity full of fluid and at a low residual pressure. This reduces the time required to make a shift into overdrive.

If this orifice comes out of place, then the residual pressure on the overdrive piston will be high enough to cause the overdrive clutch to drag and burn up.

REPAIR PROCEDURE

This procedure involves inspecting the orifice for looseness in the overdrive piston retainer.

1. Remove the overdrive unit from the transmission as outlined in the service manual.

2. Remove the overdrive piston from the piston retainer on the back of the transmission.

Figure 1:

3. Looking at the back of the transmission, the orifice plug is located behind the .075" diameter hole at the bottom (6 o'clock position) of the piston retainer (Figure 1).
4. Carefully insert a wire, such as a straightened paper clip, into this hole. If the orifice plug is in place, the wire will only go in 3/8". If the orifice plug has come out of place, the wire will go in 3/4".

5. If the orifice plug is still in place, refer to the diagnostic chart in the service manual for other possible causes of the clutch failure.

6. If the orifice plug has come out of place, it will be necessary to disassemble the transmission as outlined in the service manual. The piston retainer cannot be removed otherwise. There is a snap ring that retains and locates the reverse drum, on the forward end of the hub portion of the piston retainer.

Figure 2:

7. After disassembling the transmission and removing the piston retainer, locate the small black nylon orifice plug. It will be trapped in a passage between the case and the piston retainer (Figure 2).
8. Using a small flashlight, examine the orifice plug looking for a restriction. Both sides of the orifice plug have a small screen protecting the actual orifice plug hole. If the hole appears to be plugged, replace it using a new orifice plug PN 4412583.

9. Insert the new orifice plug fully into the hole in the piston retainer. The orifice plug can be installed either way.

10. Carefully make four punch marks with a center punch around the hole and close to the edge (Figure 2). The intent is to deform the aluminum into the hole, so that the orifice plug cannot come back out.

11. Repair the overdrive as necessary and reassemble the transmission.


POLICY: Information only