3-2 TIP-IN FLARE/SLIP-BUMP AT SPEEDS BETWEEN 18-24 MPH

Subject: 1-2 TIP-IN FLARE/SLIP-BUMP AT 18-24 MPH (INSTALL NEW PARTS)

Models Affected: 1989-91 6000 AND GRAND PRIX MODELS WITH 4T60 AND 2.8L (VIN W) OR 3.1 L (VIN T)

This bulletin has been revised to add a statement under "Service Procedures and to update information in chart form and include plate description under the part numbers under "Service Parts Information". This bulletin cancels and replaces bulletin 91-7-24 issued 1191.

BULLETIN COVERS:

Some 1989 through 1991 6000 or Grand Prix models equipped with a 2.8L (VIN W) or 3.1L (VIN T) engine and a HYDRA-MATIC 4T60 transaxle may exhibit a 3-2 light throttle tip-in flare/slip-bump condition at 18-24 MPH. A new 3-2 line control system and spacer plate are now available that will better control the transaxle operation. These conditions can be corrected by replacing the components listed under "Service Procedure".

SERVICE PROCEDURE: (Figure 1) ------------------------------- To repair a 3-2 light throttle tip-in flare/slip-bump condition at 18-24 mph, first verify the vacuum modulator line does not have a plugged orifice. Then order and install the parts for the appropriate model listed under "SERVICE PARTS INFORMATION".

IMPORTANT: Do not interchange parts between the two different 3-2 line control systems located in the channel plate assembly or the following two misbuilds could occur:

1. All upshifts at the minimum shift speed (early) for any throttle position. This would be caused by the 3-2 line control valves (both primary (431) and secondary (436)) being used with the spacer plate assembly for the plug line control valve (430) ; the valves will not work correctly because there are no fluid passage holes in the spacer plate assembly designed to function with the plug valve.

2. All 2-3 upshifts at minimum shift speed (early) for any throttle position. This would be caused by using the 3-2 line control plug (430) with the new spacer plate assembly designed to function with the 3-2 line control valves (both primary (431) and secondary (436)).

DATE OF PRODUCTION CHANGE:

The new 3-2 line control system and spacer plate were implemented into production starting December 13, 1990 (Julian Date 347).

SERVICE PARTS INFORMATION:

NOTE: All four packages listed below contain a spacer plate. In the cases where two packages are to be used, only the spacer plate from either 8675992 or 8675993 should be used as indicated. Do not use the spacer plate from 8662992 or 8662993.

-CHART "A"- For CHH, CJH, YKH, or YLH Model Transaxles Built BEFORE March 27, 1989 (Julian Date 086)

CHH and YKH Use ALL parts in Use All parts in before 086 8662992 EXCEPT plus 8675992 INCLUDING the spacer plate the spacer plate

CJH and YLH Use ALL parts in Use all parts in before 086 8662993 EXCEPT plus 8675993 INCLUDING the spacer plate the spacer plate

Models built ON or AFTER March 27,1989 (Julian Date 086) will require all parts included in the package indicated.

-CHART "B"- For transaxles built on or after March 27, 1989 (Julian Date 086)

CHH YDH YKH Use all parts in LMH YSH 8675992 Including the spacer plate

CJH YHH YLH Use all parts in LNH YTH 8675993 INCLUDING the spacer plate

Listed below are the contents of the 3-2 Slip-Bump kits 8675992 and 8675993.

A list of the contents of 8662992 and 8662993 can be found in Dealer Service Bulletin 89-7-32.

Part Model Number Description Usage ------- -------------------------- ------ 8675992 Package, 3-2 Slip-Bump Kit CHH - Instruction Sheet YDH - Valve, 3-2 Line Control Valve Primary (431) YKH - Valve, 3-2 Line Control Valve Secondary (436) LMH - Retainer, 3-2 Line Control (435) YSH - Spring, 3-2 Line Control (432) - Plate, Valve Body Spacer (31)

8675993 Package, 3-2 Slip-Bump Kit CJH - Instruction Sheet YHH - Valve, 3-2 Line Control Valve Primary (431) YLH - Valve, 3-2 Line Control Valve Secondary (436) LNH - Retainer, 3-2 Line Control (435) YTH - Spring, 3-2 Line Control (432) - Plate, Valve Body Spacer (31)

Part are currently available from GMSPO.

SERVICE NOTES:

Use applicable labor operations and times.

The 3. 1L (VIN V) turbo Grand Prix models OLAH and OYRH will be ad- dressed in a later bulletin for the 3-2 tip-in flare/slip-bump concern.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.