M/T - Shift Lever Shake/Nose in 2nd Gear
Number: 93-49-7BSection: 7B
Date: NOV. 1992
Corporate Bulletin No.: 267204
ASE No.: A3
Subject:
SHIFT LEVER SHAKE AND/OR NOISE IN 2ND GEAR
Model and Year:
1991-93 C/K, P TRUCKS WITH NV4500 5-SPEED MANUAL TRANSMISSION
Some owners of 1991-93 C/K, P trucks equipped with a NV4500 (RPO MT8) 5-speed manual transmission may comment that their vehicle experiences shift lever shake and/or transmission noise when the shift lever is in 2nd gear as labeled on the shift knob.
This condition may be caused by wobble in the shift sleeve (94) which results in noise as the sleeve (94) contacts the shift fork (11) and/or lever shake if the shift sleeve (94) wobble is great enough.
This condition may be corrected by replacing the three/four synchronizer assembly (91-94), the 3rd speed gear (87/89), the main drive clutch gear (95) and the shift cover assembly (8). The synchronizer and gears have revised teeth for improved mating and the cover features a revised detent in the 3-4 shift rail to reduce lever shake.
VEHICLES INVOLVED:
Some 1991-93 C/K, P trucks equipped with a NV4500 5 speed manual transmission built prior to the following VIN breakpoints:
Detroit (3) P3100000
Ft. Wayne (Z) PZ100000
Janesville (J)
3500 HD PJ100008
Crew Cab PJ303097
Oshawa (1) P1119152
Pontiac (E) PE111276
SERVICE PROCEDURE:
Refer to the appropriate Unit Repair Manual (Section 7B2, New Venture Gear 4500 Manual Transmission) for Unit Disassembly and Assembly and Mainshaft Disassembly and Assembly. Follow the procedures listed to:
- Remove the mainshaft assembly (57-94) from the transmission.
- Remove the three/four synchronizer assembly (91-94) from the mainshaft.
- Remove the third speed gear (87/89) from the mainshaft.
- Install the new third speed gear (87/89)
- Install the new three/four synchronizer assembly (91-94)
IMPORTANT:
A new synchronizer assembly can change mainshaft endplay. Endplay should be checked and must be .002"-.006". Change mainshaft bearing shims (141) as required.
- Install the new main drive clutch gear (95) to the main drive gear (98).
- Install a new shift cover assembly (8). This new cover requires the installation of a new vent tube (52) and new reverse fork pads (12). Transfer the shift stub lever assembly including the boot seal (1-4), and back-up switch and gasket (50-15) from the previous cover.
IMPORTANT:
The new vent tube must be installed facing forward pointing up 15 to 35 degrees from horizontal. Refer to the existing vent tube for correct position.
The following parts are not reusable and must be replaced upon reassembly:
- Mainshaft nut (28 or 32)
- Rear retainer (extension) bolts (33)
- Drive gear bearing retainer bolts (113)
- Mainshaft bearing retainer plate bolts (128)
The following fastener tightening specifications update the 1991 and 1992 Unit Repair Manual and should be used:
- Countershaft retainer plate-to-case bolts 35 N-m (26 lbs.ft.)
- Mainshaft retainer plate-to-case bolts 35 N-m (26 lbs.ft.)
- Main drive gear retainer-to-case bolts 31 N-m (23 lbs.ft.)
- Shift cover-to-case bolts 28 N-m (21 lbs.ft.)
- Rear (extension) oil retainer-to-case bolts 54 N-m (40 lbs.ft.)
- Vibration damper mounting nut (4WD) 441 N-m (325 lbs.ft.)
- Yoke assembly mounting nut (2WD) 441 N-m (325 lbs.ft.)
Sealants which should be used for reassembly are noted below:
P/N 1052942 Anaerobic sealant
- Shift cover-to-case flange
- Rear extension housing-to-case flange
- Main drive gear bearing retainer-to-case flange P/N 12346004 Pipe sealant with TEFLON
- Drain and fill plugs
- Main drive gear bearing retainer bolts (circle the retainer bolt holes with sealant)
IMPORTANT:
This transmission requires a special synthetic lubricant P/N 12345871. Do NOT substitute any other lubricant as internal transmission damage may occur.
SERVICE PARTS INFORMATION
Parts are currently available from GMSPO.
WARRANTY INFORMATION
Labor Operation: T7586
Labor Time (hrs.): C K P
3.5 4.3 4.1
H.D. 3500 3.7 3.7
Transmission Shift Mechanism and Case Components Legend: Exploded View
Transmission Gear Components Legend: Exploded View