Harsh 3-2 Coastdown Bump 3.8L or 4.5L At 15-22 MPH:
1985-87 Cutlass Ciera/Cruiser, Eighty Eight, Ninety Eight, And Toronado/Trofeo, With Transaxles Built Prior To December 18, 1986 (Julian Date 352) And 3.8L Engines
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 first 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 P/N 8668123. Refer to the chart to determine the transaxle model and Julian Date when the new springs were first used in production units.
If the condition persists make sure the 3-2 coastdown valve (located in the oil pump body) is not stuck and moves treely in its bore.