DIAGNOSIS INFORMATION FROM EXCHANGE PROGRAM

Model and Year: 1986 1/2-88 FIERO, 1987-88 6000, SUNBIRD, AND GRAND AM AND 1988 GRAND PRIX

"This bulletin supersedes bulletin 88-7-42, dated 10/88. This bulletin is being revised to add 3 steps to Check Clutch Spin Down Time."

BULLETIN COVERS: (Figure 1) --------------- Diagnosis information on 1986-1/2 through 1988 vehicle applications equipped with an HM-282 five-speed manual transaxle. This information was gained from the expired exchange program assembly analysis of returned transaxles. Before repairs are attempted, refer to the following diagnostic chart as a guide.

SERVICE ACTION

Preliminary Diagnosis Procedure:

-Insure correct fluid level and proper type. -Insure that the clutch is working properly (spin-down time and lost motion). -Insure that all engine and transaxle mounts are tight.

SERVICE PARTS INFORMATION

Parts are currently available from GMSPO.

SERVICE MANUAL REFERENCE

Information in this bulletin is intended to supplement the HM-282 Section of your Service Manual.

1986 1/2, 1987 AND 1988 HM-282 DIAGNOSTIC CHART

NOTE: For all figure references, refer to the HM-282 on-car service section 7B3 or the HM-282 Unit Repair Section 7B3A of the 1988 Service Manual.

Condition Inspect Component For Cause System ----------------- ---------- (General Desc.) --------------- SHIFTING: -------- Excessive Shift o Proper Type of Fluid - Improper Fluid or Level, Effort Required And Level Of Fluid USE G.M. P/N 12345349 In All Forward (automatic transmission Gears (Engine fluid or engine oil does Running) not work well with synchronizers resulting in increased shift effort) Refer to Bulletin: Chevrolet 88-158-7B

o Clutch - Improper Spin-down time. To check clutch spin down time:

1. Run the engine at a normal idle with the transaxle in neutral and the clutch engaged.

2. Disengage the clutch, wait nine seconds and shift the transaxle into reverse.

3. If a grinding noise is heard, refer to the Clutch Diagnosis section of your Service Manual.

(Clutch Spin-down Time OK, Lubricant Type and Level OK)

Into Or Out Of o Shift Cable (Remove - Binding, Kinked, Worn Gear (Same Effort Cable From Transaxle Or Not Routed Or With Engine Running And Test For Ease Of Secured Correctly Or Not) Movement

o Shifter Mechanism In - Worn Or Damaged Car (Disconnect Cables In Car And Move Shifter To Test For Ease Of Movement)

o Shift Lever Nut (137) - Loose, Allowing The Shift Lever To Bind While Shifting. Refer To Bulletin: Chevrolet 88-233-7B

o Shift Rail(s) (184) - Binding Shaft/Rails. (190) and (197) Of Affected Gear

o Shift Rail Bushing(s) - Worn/Damaged Binding (99) and (176) Of Rails Affected Gear

Reverse Gear o Reverse Idler Gear - Gear Teeth Mating End (103) Input Shaft (17) Damaged, Mutilated And Reverse Gear (26) (Mushroomed) (Customer Hitting Reverse On 5th to 4th Downshift). Once Damaged/Worn Parts Are Replaced, Have Customer Change Shift Pattern (Not Round Off The 5th To 4th Downshift).

o Reverse Lever (153) - Bent (both ears must be in same plane)

o Reverse Shift Rail - Binding/Worn Assembly (180) Components

o Reverse Shift Rail - Worn Or Missing Bushing (167)

o Engine Idle Speed - Too High Causing Excessive Effort (Also 1st Gear)

Hard To Shift Into o Select Cable (Remove) - Binding, Kinked, Worn Shift Gates (1-2, Cable From Transaxle Or Not Routed Or 3-4, 5-reverse) And Test For Ease Of Secured Correctly (side to side) Movement)

Fiero Only o Ball Stud On Select - Out Of Position, Hard Shifting Into Lever Binding, Causing Hard Shift Gates - (side Shifting Into Gates. to side) Refer To Bulletin: Pontiac 88-7-26

Hard Shift Into o Cover (140) - Cover Installed Too 1-2 Gate Deep Or The Top Of The Cover Is Caved In, Not Allowing Full Travel Of The Shift Shaft (155) EXCESSIVE CLUTCH PEDAL EFFORT:

(Early External o Clutch Fork Shaft - Corroded Or Worn (Use Release Models (165) And Inner Clutch Service Clutch Fork Fork Bushing (177) On Shaft With Chromed End, Units Built Before G.M. P/N 8672937). October 26, 1987. On Al so Order And Repl ace This Date A Needle Bushings (Not Included Bearing (217) Is Used In Parts Package) Instead Of Bushing (177).

o Input Shaft Bearing/ - Worn, Gouged And/Or Sleeve Assembly (21) Cracked At Flange, Binding Clutch Release Bearing (22)

- Lack Of High Tempera- ture Grease

- Excessive Clutch Disc Dust Contaminating Grease, Causing In- creased Effort

o Clutch Fork Shaft - Clutch Fork Parallelism (165) Or (216) (Fork Fingers Not Touching Release Bearing (22) At The Same Time. This Causes The Release Bearing To Bind On The Input Shaft Bearing/ Sleeve Assembly (21).

o Clutch Fork Shaft - Worn Or Damaged Bearings Or Bushings (163), (177) Or (217)

o Refer To Clutch And Sl ave Cyl i nder Diagnosis

No Shift Into 1st o Fork Retainer Pin - Missing, Backed Out And 2nd Gear (Lever (193) On Units Built From Vibration. Replace Will Shift But No Before December 11, 1st/2nd Shift Rail Gear Engagement) 1987. On This Date The Assembly (190). All Fork Pin Hole In The Service Parts Have The Rail (195) Was Made Tighter Fork Pin Rail Smaller So The Pin Will Hole Not Back Out

No Shift Into 3rd o Fork Retainer Pin - Missing, Backed Out And 4th Gear (Lever (186) On Units Built From Vibration. Replace Will Shift But No Before November 25, 3rd/4th Shift Rail Gear Engagement 1987. On This Date The Assembly (184). All Fork Hole Pin In The Service Parts Have The Rail (189) Was Made Tighter Fork Pin Rail Smaller So The Pin Will Hole Not Back Out

No Shift Into 5th o Fork Retainer Pin - Missing, Backed Out Gear (Lever Will (197) On Units Built From Vibration. Replace Shift But No Gear Before November 25, 5th Shift Rail Assembly Engagement) 1987. On This Date The (197). All Service Fork Pin Hole In The Parts Have The Tighter Rail (202) Was Made Fork Pin Rail Hole Smaller So The Pin Will Not Back Out

HOP OUT

Slips Out Of Gear On Acceleration Or Acceleration (Transmission Under Load)

lst Gear o Thrust Bearing (51) - Missing Or Worn And/Or Thrust Washer (Allowing Too Much (52) End Play)

lst Gear And/Or o 1st/2nd Synchronizer - Damaged Or Worn 2nd Gear Sleeve (43) And/Or Hub Spline Lock On Hub (47) And/Or Sleeve

3rd Gear And/Or o 3rd/4th Synchronizer - Damaged Or Worn 4th Gear Sleeve (9) And/Or Hub Spline Lock On Hub (13) And/Or Sleeve

5th Gear o 5th Synchronizer - Damaged Or Worn Sleeve (30) And/Or Spline Lock On Hub Reverse Gear (26) And/Or Sleeve (Coast i.e. Not o Shift Rail (s) Detent - Damaged, Worn Or Acceleration Or Assembly (189), (195), Missing Parts Deceleration) (202), (170) And (171) (Any Gear) Of Affected Gear

HARD SHIFTING

Neutral To 1st o 1st Output Gear (49) - Updated For Start Of Production 1988. Changed Angle Of Clutching Teeth To Help Shift (110 To 118) Hard 1st-2nd o Output Gear Shim (87) - Missing Or Too Thin Causing Too Much End Play For Output Shaft (53) 1st And/Or 2nd o lst And/Or 2nd - Bronze Material Blocking Rings (48) Transfer To Speed Gear And (41) On Units Cone(s). Replace Speed Built Before Dec. 11, Gear Of Affected Gear. 1987. Change All Service Parts Are Manufacturing Process Updated Parts To Make Bronze More Durable

3rd, 4th And/or o 3rd, 4th And/Or 5th - Bronze Material 5th Blocking Rings (14), Transfer to Speed Gear (7) And/Or (31) On of Affected Gear. All Units Built Before Service Parts Are Updated December 31, 1987. Parts Changed Manufacturing Process To Make Bronze More Durable

Hard Shift Into o Reverse Lever (153) - Bent 5th Gear

Unable To Shift o Reverse Shift Rail - Missing Parts Out Of 5th Gear Assembly (180) Especially Gear Disengage Roller (182)

Unable To Shift o Snap Ring And Detent - Missing Parts Into Any Gear Plug (209) And (210)

Block-Out In Any o Synchronizer Sleeve - Replace Sleeve Of Forward Gear Of Affected Gear (9), Affected Gear If There (43) And/Or (30) Is No Bronze Transfer From Blocking Ring To Speed Gear Cone. Refer To Above lst-2nd And/

Or 3rd, 4th And 5th LOCKED-IN GEAR

o Shift Rail Detent - Misassembled Or Worn Assembly (171), (169), Parts (189), (195), (196), (202) And (183). (This Will Happen After An Overhaul)

o Detent Lever Assembly - Disassembled Or (145) Severely Damaged Unable To Shift o Reverse Shift Rail - Missing Parts Out Of 5th Gear Assembly (180) Especially Gear Dis- engage Roller (182)

GEAR CLASH/ GRINDS

In All Forward o Proper Type Of Fluid - Improper Fluid Or Gears And Level Of Fluid Level, Use G.M. P/N 12345349 (Automatic Transmission Fluid Or Engine Oil Does Not Work Well With Synchronizers Resulting In Gear Clash). Refer To Bulletin: Chevrolet 88-158-7B

(Clutch Spin-Down Time OK, Lubricant Type And Level OK)

1st And/Or 2nd o lst And/Or 2nd - Bronze Material Transfer Blocking Rings (48) To Speed Gear Cone(s). And (41) On Units Replace Speed Gear Of Built Before Dec. 11, Affected Gear. All 1987. Changed Service Parts Are Manufacturing Process Updated Parts To Make Bronze More Durable

3rd, 4th And/Or o 3rd, 4th And/Or 5th - Bronze Material 5th Blocking Rings (14), Transfer To Speed Gear (7) And/Or (31) On Cone(s). Replace Speed Units Built Before Gear Of Affected Gear. Dec. 1, 1987. Changed All Service Parts Manufacturing Process Are Updated parts To Make Bronze More Durable

In All Forward Gears (Clutch Spin-Down Time OK, Lubricant Type And Level OK) o Refer To Clutch - Improper Spin-Down Diagnosis Time

NOISE

Neutral Rattle o Loose Vacuum Line On - Improper Running (Clutch Engaged) Engine Engine Transferring Irregular Pulses To Transaxle Gear Set, Causing Rattle

(Will Be Loudest o Disconnected Spark Plug When The Accessories Wire Are On, As When The Air Conditioner o Out Of Tune Engine Compressor Is Cycling) o Idle RPM

o Engine Timing

(Will Be More o Slight Rattle Is Normal Noticeable With Because Clutch Disc The Window(s) Does Not Have An Anti- Down) Rattle Device. (Will Not Cause A Durability Concern)

o Refer To Clutch Diagnosis

o Input Shaft Bearing/ - Broken Flange, Sleeve Assembly (21) Rubbing

o Input Gear Bearing - Damaged Or Worn (93) Bearing

o Speed Gear Bearing(s) - Damaged Or Worn (16) and (5) Bearing

o Bearing Races (17) - Damaged Or Worn Races And (6)

o Input Shaft (17), 3rd - Damaged Or Worn Thrust Input Gear (15), 3rd- Surfaces 4th Synchronizer Clutch Hub (13) And Fifth Input Gear (3)

o Clutch Release - Damaged Or Worn Bearing Assembly (22) Bearing Noise In All o Clutch And - Cracked, A Foreign Gears (Bearing Differential Housing Object Between Output Noise) (20) At The Output Shaft And Differential Bearing Race (56) (Broken Speedo Signal Bore Assembly (172) Driven Gear Shaft, Or Loose Bolt, Lever Retainer Pin Or Roll Pin)

o Output Gear Bearing - Worn Or Damaged. (86) Replace Both Bearings (86) and (93) With Bearings In Overhaul Kit G.M. P/N 8672918

o Shift Rail Guide Bolt - Loose, Rubbing On Gear (18)

Differential o Output Bearing Race - Installed Upside Retainer (178) Down, Ring Gear (70) Rubbing On Retainer Because Cutout For Ring Gear Is Now Installed Down

(Will Be Noisy o Detent Holder Cover - Not Installed Flush With The Car (174) With Bore, Clutch Moving Or Not Plate Rubbing On Moving.) Cover

Final Drive Noise o Output Shaft (53) And - Worn Or Damaged (64-80 KMH, 40-50 Differential Ring Gear MPH In 4th Gear). (70) On Units Built Before April 15, 1987. On This Date The Gear Tooth Profile Was Changed To Lessen Noise

LEAKS

o Fluid Level - Overfilled Because Of Improper Checking Procedure. Fluid Level Is Not Checked Through FillTube That Bolts Onto Side Of Housing

Refer To Bulletin: Chevrolet 88-13

o Fluid Level Indicator - Old Style Indicator Not Assembly (110) And Sealing Bore. Replace Bore With G.M. P/N 22540197

Refer to Bulletin: Chevrolet 88-69-7B

(From Clutch Area)

Slave Cylinder o Refer To Slave Cylinder Leak Diagnosis

o Input Shaft Bearing/ - Worn Or Damaged Seal Sleeve Assembly (21) - Worn Rollers, Allowing Input Shaft To Move More Than Seal

o Input Shaft (17) - Damaged Surface That Mates With Seal

o Detent Holder Cover - Damaged (174)

o Reverse Idler Bolt - Loose (94) - Lack Of Proper Sealant

o Shift Shaft Cover - Reused Or Damaged (140) - Missing Snap Ring (139) Differential Part o Oil Drive Axle Seal(s) - Worn Or Damaged Seal Of Housings (23) And/Or Equal Drive Axle Extenders Seal

(Allowing The o Thrust Side Gear - Worn Drive Axle To Move Washer(s) (65) In More Than Axle Differential Assembly Seal, Causing Leak) Case (61)

o Speedo Signal Assembly - Worn Or Torn Seal (220) - Bore Damaged - Debris In Seal Groove Of Sensor

o Speedo Signal Assembly - Internal Leak (172)

o Oil Drain Plug (79) - Loose - Cross Threaded

o Oil Drain Plug - Work, Damaged Or Washer (80) Missing

o Shift Shaft Seal - Worn, Damaged Or (208) Missing

o Back-Up Lamp Switch - Loose Assembly (219) - Lack Of Proper Sealant

From Side With o Transmission Case End - Damaged Warped Or Lack Plate Plate (90) Of Sealant

o Bolt(s) (91) - Loose Or Lack Of Sealant

o Output Gear Bearing - Too Thick, Not Allowing Retainer Shim (87) Transaxle Case End Plate (90) To Properly Seat

o Bolt (205) - Loose - Lack Of Proper Sealant - Cross Threaded

BACK-UP LAMPS DO o Back-Up Lamps - Burned Out NOT TURN ON o Check Fuse

o Reverse Rail Bushing - Omitted (98)

o Back-Up Light Wiring - Loose Or Corroded Circuit Connections

o Back-Up Lamp Switch - Defective Assembly (219)

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.