Riviera V6-231 3.8L Turbo VIN 8 4-bbl (1983)
Clutch: All Technical Service Bulletins
A/T - No Fourth Gear
Model Year
1983
Bulletin No.
83-94
File In Group 70
Number
10
Date
Apr, '83
SUBJECT:
NO FOURTH GEAR - 1982 - '83 THM 325-4L TRANS.
Some 1982 and 1983 THM 325-4L transmissions may experience a no fourth gear condition. The following diagnosis procedure will aid in determining
the cause for this condition.
DIAGNOSIS PROCEDURE
Test drive the vehicle applying a light throttle in drive range to about 30-35 m.p.h. (Third gear). Move the selector lever into manual second and release
the throttle. The transmission should downshift and coastdown overrun braking should occur.
1.
If coastdown overrun braking does occur, refer to the diagnosis procedure for no fourth gear in your Service Manual.
2.
If coastdown overrun braking does not occur, remove the transmission from the vehicle. Inspect the overrun clutch housing for a break in the
hub weld. If the hub weld is broken, the cause is due to misaligned pinions in the overdrive carrier.
FIGURE 1 - OVERRUN CLUTCH
FIGURE 2 - OVERDRIVE CARRIER
In all instances where the hub weld is broken on the overrun clutch hosing, both the overrun clutch housing (Part Number 8635941, Figure 1) and the
overdrive carrier (Part Number 8635036, Figure 2), must be replaced.
