FRONT WHEEL DRIVE M/T REVISED SERVICE INFORMATION

MODELS AFFECTED: SKYLARK (1980-1983) AND SKYHAWK (1982-1983)

Buick has offered manual 4-speed front wheel drive manual transaxles in its Skylark "X" since 1980, and on its Skyhawk since 1982. This bulletin upgrades existing information on these units. Areas covered are (1) shift effort and feel, (2) worn shifter forks, and (3) gear noise.

I. SHIFT EFFORT AND SHIFT QUALITY

A. First check to be sure no assembly aids are left on car. In car, 5/32" pin locks shifting lever mechanism in 1st gear.

"Yoke clip" holds shifter in 1-2 gate, no reverse or 3-4 shift is possible.

Underhood: Inspect shifter shaft below shift lever to see that no biasing clip (large hairpin) is present.

B. If car is new, shift feel may be improved by shifting through the gears many times (25-50), which conditions the transaxle.

C. Next perform the following adjustment - two (2) man procedure.

1. Disconnect battery cable.

2. From inside car, shift into lst gear and hold in position all the way forward and to the left as far as it will go.

3. Underhood, loosen nuts on selector lever and shift lever.

4. Underhood, remove lash in select lever (top lever) by pushing it toward driver side of car (clockwise) and holding it while nut is tightened.

Do Not Use Power Tools

5. Repeat step 4 for shift lever, removing lash in same manner and tighten nut.

6. Recheck adjustment by shifting transmission from inside car while observing motion of both shift levers underhood. Little or no movement of select lever should be noted on 1-2 or 3-4 shift. If excessive movement of select lever is noted, repeat entire adjustment procedure (steps 2-6) before proceeding.

7. Drive car and evaluate improvement.

Before Removing Transaxle, Verify Shift Problem Is Internal To Gear Box

1. Disconnect cables at select and shift levers.

2. Check shifter and cables for freedom of operation. Repair as necessary.

3. Manually shift transaxle with select and shift levers to check for ease of operation and verify problem is in transaxle.

II. SHIFT FORKS

With transaxle removed, inspect shift forks for wear (reference Service Bulletins 81-T-62 and 81-1-161). If shift fork is worn or binds, replace both shifter fork and synchronizer. The correct part numbers are listed below:-

1st-2nd Gear Shift Fork 14008232

1st-2nd Gear Synchronizer 14062629

3rd-4th Gear Shift Fork 14009112

3rd-4th Gear Synchronizer 14062631

When reassembling transaxle, use shimming procedure_p ovided in Section II, D

III. GEAR NOISE

Resolving a transaxle gear noise or whine complaint begins with a good diagnosis to determine if the noise is related:

- to the transaxle at all - to the noise paths into the passenger compartments - to the parts or assembly of the transaxle.

A. Is it transaxle noise at all?

Other noises are sometimes mistaken for gear noise, especially higher pitched airborne noises such as wind whistle, grill noise, tire noise, etc. Transaxle gear noise will be throttle and car speed sensitive; i.e. gear noise will increase in pitch as speed increases.

NOTE: 1st and 2nd gear noise: Don't be too critical, as these are not "cruising gears".

3rd and 4th gear noise: You must differentiate between 3rd/4th gearset noises and final drive gearset noises before removing transmission from car.

To determine if it is final drive gear noise or speed gear noise, drive the car at a constant speed and shift between third and fourth gear. If the pitch of the noise stays the same, it is final drive gear noise. If the pitch changes drastically, it is speed gear noise.

NOTE: Recognize that determination is difficult ("X" car noise usually is speed gears and "J" car noise is usually final drive gears).

B. Check routes for noise into passenger compartment.

Because the gears in the transaxle are in mesh, some noise or whine will be generated with perfect gears. Noise isolation built into the car eliminates most of this "normal" noise intrusion into the passenger compartment. Once the gear noise has been determined to be authentically from the transaxle, the following noise isolation items should be checked before transaxle removal.

1. Shift cable installation - make sure cables are snapped squarely into the shifter and grommet is snapped firmly into place in dash.

2. Shift cable routing - cables should be free from kinks, sharp bends and "grounding out" against other components. The carpet should not cause any kinks or binds in the cables.

3. Dash insulation - should be checked to make sure all "holes" are sealed.

C. Transaxle Gear Replacement

If the noise persists after checking routes for noise into passenger compartment, then the transaxle should be removed to remedy:

- poor machining of ears - improper shimming (preload)

NOTE: A few hand selected matched gear sets for final drive units and third and fourth gears are available. If a service replacement gear set does not correct the noise, contact your Zone Office.

D. Shimming Procedure (Preload)

It is essential that the following new shimming procedure be used in reassembly of the transaxle (same as 1982 Service Manual except step 7, which is revised). The complete procedure follows.

Selection of the preload shims for reassembly can begin when the input and output shaft assemblies and the differential assembly are reassembled and ready to be installed into the transaxle case.

1. Place the transaxle case into holding fixture J-28408.

2. With the (3) L.H. bearing races installed in the case, place the input and output shaft assemblies and the differential assembly into their installed positions.

Place the (3) R.H. bearing races onto their respective bearings. See Figure 7B-31A.

3. Position (3) gages; J-26935-2 on input bearing and J-26935-4 onto output bearing and J-26935-3 on the differential bearing. Be sure the bearing races fit smoothly into the bores of the gage tools.

4. On J-26935-4 (output shaft), install metal oil shield retainer into bore on top of tool.

5. Carefully assemble the clutch cover over the (3) gages and onto the case, using (7) spacers placed evenly around the perimeter. Retain with bolts provided. See Figure 7B-33A.

Draw the cover to the case by tightening alternately and gradually. Torque bolts to 10 ft. lbs.(12 N.m.). This will compress all three gage sleeves.

6. Rotate each gage to seat the bearing. Rotate the differential case through three revolutions in each direction.

7. With the three gages compressed, the gap between the outer sleeve and the base pad is larger than the correct preload shim at each location. Carefully compare the gap to the available shims. Determine the largest shim that can be placed into differential gap and drawn through without binding. Use the next size smaller shim for this location. Repeat procedure to select output shaft shim. On the input shaft, repeat this procedure and use a shim 2 sizes smaller than the largest shim that can be drawn through without binding. See Figure 7B-34A.

8. When each of the three shims has been selected, remove the clutch cover, spacers (7) and gages (3).

9. Place the selected shims into their respective bores in the clutch cover, add the metal shield and then install the bearing cups using special tool J-26936 on input shaft and J-23423-A on output shaft cup and J-26938 on the differential side bearing cup.

10. After assembly, check end play of input shaft. If any end play is present, replace shim with next size larger at this location.

11. Reinstall transaxle in car and perform shift cable adjustment as outlined previously.

MANUAL TRANSMISSION SERVICE BULLETINS

Bulletin Number Status

80-T-48 Subject: Rough Clutch Pedal Operation Still Applicable

Models Affected: 1980 Skylark 80-T-55 Subject: Four Speed Manual Transmission Obsolete - Refer 3rd and 4th Gear Disengagement to New Bulletin

Models Affected: 1980 Skylarks with Four Speed Manual Transmission 80-I-145 Subject: Worn Shift Forks Obsolete - Refer to New Bulletin Models Affected: 1980 Skylark Equipped with Manual Trans.

80-I-179 Subject: Manual Transaxle Shim Selection Obsolete

Models Affected: 1980 Skylark 81-T-23 Subject: Self-Adjusting Clutch Mechanisms Obsolete - Recall Campaign Models Affected: 1980-81 Skylarks 81-T-25 Subject: Diagnostic Guide - Skylark Manual Obsolete Transaxle Shift Conditions

Models Affected: 1980 and 1981 Skylarks 81-T-31 Subject: Rattle on Turn Still Applicable, Must Use New Models Affected: 1980 and 1981 Skylark Adjustment With Manual Trans. 81-T-62 Subject: Four Speed Manual Transaxle Still Applicable Inspection

Models Affected: 1980 and Early 1981 Skylarks 81-T-161 Subject: Transaxle Special Policy Still Applicable

Models Affected: 1980 and Early 1981 Skylarks 81-C-17 Subject: Clutch Linkage Mechanism Still Applicable

Models Affected: 1980 and 1981 Skylarks With Manual Trans.

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.