Bravada V6-262 4.3L VIN Z (1991)
Band: Technical Service Bulletins
A/T - 3-4 Clutch/2-4 Band Service Information
NUMBER:
91-T-196
CORP.REF.NO: 177119
DATE:
September 1991
SECTION:
7
SUBJECT:
3-4 CLUTCH/2-4 BAND SERVICE INFORMATION
MODELS/YEARS:
ALL MODELS WITH HYDRA-MATIC 4L60
TRANSMISSION
The following information will be helpful when servicing a HYDRA-MATIC 4L60 transmisslon for a "no third or fourth gear" or "slipping in third or
fourth gear" condition. Many root causes for these problems have been identified, and more than one cause may exist at the same time. This bulletin
covers some causes that may not be obvious when doing a normal repair procedure.
SERVICE INFORMATION:
Before servicing the transmission, check the following:
^
TV Cable Setting ---
Make sure the TV cable is set to the correct position. Never adjust the cable to hide a shift complaint or to change performance. This can mask the root
cause and damage the transmission.
^
Fluid Level ---
Oldsmobile cannot emphasize enough how important fluid level is to transmission performance. Both high and low fluid levels can cause problems. A
low fluid level causes low line pressure. This can burn clutches by not allowing the clutch to apply qulckly enough, or by not keeping the clutch fully
applied. A high fluid level allows fluid to become foamy when the fluid is churned through the gear sets. Since air is compressible, the foamy fluid does
not apply the clutches with as much force as they need.
^
Cooler Flow ---
Perform a cooler flow check as outlined in the cooler flush procedure. Cooler lines can be partially blocked so it is important to know that cooler flow is
adequate.
During overhaul, look at the following items:
^
Filter Neck Seal ---
Examine the filter neck seal for evidence of heat set. If the seal doesn't properly seal around the filter, air can get in to the pump and cause low line
pressure or aerated fluid. Replace the seal if you suspect it doesn't fit properly.
^
Pump Body Bushing ---
Disassemble the pump and examine the pump body bushing for wear. A worn bushing can create a large leak in the pump and lower line pressure which
can cause lube flow to be cut off. Replace a worn bushing. If the bore seems to be out of round (excess wear in one area), replace the pump body.
^
3-4 Clutch Boost Springs ---
Examine the boost springs (if present) for evidence of polishing on the spring tabs. This can occur when the outer diameter of the 3-4 clutch friction
plates rub on the boost springs. Replace the boost springs as necessary.
^
Input Housing ---
Look at the splines on the inside of the input housing. If the sets of three splines show drag marks in the middle spline, the steel plates of the 3-4 clutch
are binding in the housing. New steel plates are available for service that have a smaller outer diameter to stop the binding condition. The new 3-4 clutch
plates can be used to service any HYDRA-MATIC 4L60 transmission produced after February 9, 1987 (Julian Date 040).
DESCRIPTION
NEW PART
Plate - 3rd and 4th (steel - 4 or 5 needed)
8678053
Plate - 3rd and 4th (steel - 1 needed)
8678054
