Beretta V6-173 2.8L (1989)
Clutch: All Technical Service Bulletins
A/T - Diagnosis Information LO-Reverse Clutch
Number:
89-154-7A
Section:
7A
Date:
April, 1989
Subject:
DIAGNOSIS INFORMATION - LO - REVERSE CLUTCH THM 125C/ HYDRAMATIC 3T40
Model and Year:
1980-89 A, J, L CARS WITH 125C/ HYDRA-MATIC 3T40 TRANSAXLES
TO:
ALL CHEVROLET DEALERS
This bulletin provides diagnosis information for possible inoperative Lo-Reverse Clutch assemblies used in the THM 125C/HYDRA-MATIC 3T40
transaxle.
Causes for an inoperative Lo-Reverse assembly are as follows:
In the Direct Clutch area:
^
Direct Clutch Drum Center Seal that is rolled and/or cut.
This condition would cause a cross circuit leak that would apply (drag) the Lo-Reverse clutch each time the vehicle is driven in the third gear range.
^
Driven Sprocket Support Seals - check for improperly cut angles.
In Lo-Reverse Clutch area:
^
Rolled and/or cut Lo-Reverse clutch piston seals.
^
Cup Plug Seals (improperly installed) or cut.
^
Cut O-Ring Seal on Lo-Reverse Pipe.
^
Bent and/or Leaky Lo-Reverse Pipe.
^
Bent and/or Missing Lo-Reverse Pipe Bracket.
Parts Non Conformity:
^
Porosity in the # 4 and # 5 Check ball area of the case cover (cross channel leak during 3rd gear apply).
^
# 6 Check ball not seated during apply.
^
Stuck Boost Valve.
^
Backing plate out of location.
Whenever a suspect Lo-Reverse condition exists all of the previous items should be inspected and/or replaced if necessary.
SERVICE MANUAL REFERENCE:
Whenever service to the Lo-Reverse Clutch Assembly is necessary refer to the THM 125C/HYDRA-MATIC 3T40 Unit Repair Section of your Service
Manual.
SERVICE NOTES:
The Direct Clutch in the THM 125C/HYDRA-MATIC 3T40 is only applied in 3rd gear and Reverse. The Reverse Clutch is on in the Manual Lo and
Reverse gear ranges. If a Lo-Reverse condition exists, the Direct Clutch assembly should be inspected.
