Harsh 3-2 Coastdown Bump 3.8L At 15-22 MPH
1985-87 440T4 transaxles built prior to 12-18-86 (Julian Date 352) and 3.8L enginesSERVICE PROCEDURE
A coastdown bump is obtained by allowing the vehicle to coastdown to 15-22 mph (with closed or zero throttle) and a sudden and forceful apply of the 1-2 band is felt when the transaxle shifts from third to second gear. A harsh 3-2 coastdown bump may be caused by the 1-2 servo cushion spring. This condition may be corrected by replacing the 1-2 servo cushion spring with the part listed below. Refer to the chart below to determine the transaxle model and Julian Date when the new springs were first used in production units.
Figure 7 - 1-2 Servo Assembly:
SERVICE PARTS INFORMATION
Part Number Description
8668123 1-2 Servo Cushion Spring (Item # 559, Figure 7)
Parts are currently available from GMSPO.
SERVICE NOTES
If the above condition persists make sure the 3-2 coastdown valve (located in the oil pump body) is not stuck and moves freely in its bore.