HIGH SHIFT EFFORT: 1-2 UPSHIFT 2-1 DOWNSHIFT 4 SPEED M/T

1985 SUNBIRD & FIERO WITH 4-SPEED MANUAL TRANSMISSION

Some 1985 model year subject vehicles equipped with 4-speed manual transmissions may exhibit unusually high shift efforts during 1-2 upshifts and 2-1 downshifts. This condition may be caused by excessive pre-load of the input shaft tapered roller bearings and/or uneven sliding action of the 1-2 shift fork on the shift fork shaft.

On vehicles exhibiting the described conditions, the following steps should be followed to repair the condition:

1. Ensure that the gold colored, sheet metal, clip (assembly aid) has been removed from the shift lever at the transmission. If present, this clip can be removed by pulling up on one (1) of the two (2) ears until the clip springs off the shift lever.

2. Ensure that full clutch disengagement is obtained with the clutch pedal fully depressed. This can be checked with the engine running and parking brake applied, by fully depressing the clutch pedal and after three (3) seconds slowly engaging reverse gear. If the noise of gear teeth running against each other is apparent then the clutch is not fully disengaged.

If either of Steps #1 or #2 required corrective action then the hard shift condition should be re-evaluated to see if the condition persists before proceeding.

3. If the vehicle is new, the shift feel may be changed by driving the vehicle and shifting through the gears many times (25-50), this will condition the transmission. Should the condition continue to be exhibited, then the shift cable adjustment procedure described below should be performed; this is a two (2) man procedure.

A. Disconnect the negative cable at the battery.

B. From inside the vehicle, shift the transmission into first gear and hold the shift lever all the way forward and to the left as far as possible (towards driver's right knee).

C. Underhood, loosen selector and shift cable attaching nuts at the transmission levers.

D. While maintaining the shifter position described in Step B, remove the lash in the selector lever by rotating it (pushing) toward the passenger side of the vehicle for the Fiero; for the Sunbird the lash is removed by rotating the lever (pulling it) toward the driver side. Retighten the cable attaching nut while holding the select lever in position.

E. Retighten shift cable attaching nut. Check for equal overshift by shifting transmission between lst and 2nd gears. Readjust shift cable if necessary to achieve equal overshift.

F. Recheck adjustment by shifting transmission from inside of vehicle while observing motion of both shift and select lev.ers underhood. Little or no movement of the select lever should be noted during 1-2 and 3-4 shifts. I f excessive movement of the select lever is noted, repeat procedure (Steps 3B-3F) before proceeding.

DO NOT USE POWER TOOLS DURING STEPS 3E AND 3F.

4. Remove the transaxle from the vehicle and disassemble according to the relevant steps described in the 76mm (4-speed) manual transaxle section of the service manual.

For transaxles with date code stamps X5M01 to X5T31 the 1-2 shift fork should be replaced using a new fork, P/N 14073789 (transaxles with code stamps X5A01 thru X5K31 already have this new part installed).

For all 1985 transaxles with the subject complaint, the input shaft bearing shim should be re-selected following the procedure described in the service manual except: DO NOT change the output shaft or differential bearing shims.

NOTICE: When selecting the new input shaft shim ensure that the selected shim is two (2) classes thinner than the thickest shim that will fit all the way around the gap in the shim gauge. Install the selected shim and re-assemble and re-install the transaxle following the service manual procedures. Re-attach the shift and select cables to the transmission using the procedures described in Section 3 of this publication.

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.