General Overhaul Service Procedures
GENERAL SERVICE PROCEDURESSERVICE METHODS
When servicing the transmission, it is recommended that upon disassembly of a unit, all parts should be cleaned and inspected as outlined under Parts Cleaning and Inspection.
1. Before disassembly of the unit, thoroughly clean its exterior.
2. Disassembly and reassembly of the unit and the subassemblies must be made on a clean bench. As in repairing any hydraulically operated unit, cleanliness is of the utmost importance; therefore, the bench, tools, and parts must be kept clean at all times.
3. Before installing bolts into aluminum parts, always dip screws into transmission fluid to prevent bolts from galling the aluminum threads and also to prevent them from seizing.
4. Always use a torque wrench when installing bolts into aluminum parts to prevent possibility of stripping the reads.
5. Seal protecting special tool must be used when assembling 2nd clutch piston to prevent damage to seal. The slightest flaw in sealing surface of seal can cause an oil leak.
6. As aluminum castings and valve parts are very susceptible to nicks, burrs, etc., special care should be exercised when handling them.
7. Internal circlips should be expanded and external circlips compressed if they are to be reused. This will insure proper seating when installed.
8. Replace all O-rings, gaskets and oil seals that are removed. Seal rings should not be removed unless damaged.
9. During assembly, all internal parts must be lubricated with automatic transmission fluid sufficiently.
10. Slightly smear grease to oil seal lips when installing.
PARTS CLEANING AND INSPECTION
During inspection and reassembly, all parts should be thoroughly cleaned with cleaning fluid and then air dried. Wiping cloths or rags should not be used to dry parts. Do not use solvents on neoprene seals, lined clutch plates or selective washers. All oil passages should be blown out and checked to make sure that they are not obstructed. Small passages should be checked with tag wire. All parts should be inspected to determine which parts are to be replaced.
The various inspection of parts are as follows:
1. Inspect linkage and pivot points for excessive wear.
2. Check bearings and thrust surfaces of all parts for excessive wear and scoring.
3. Check for broken seal rings, damaged ring lands and damaged threads.
4. Inspect seals and O-rings.
5. Check mating surfaces of castings and plates for burrs. Irregularities may be removed by lapping the surface.
CLUTCH PLATE AND PISTON SPRING DIAGNOSIS
1. Lined Plates
Dry plates and inspect for pitting, flaking, wear, glazing, cracking, charring and chips or metal particles imbedded in lining.
If a lined plate shows any of the above conditions, replacement is required.
2. Steel Plates
Dry plates and check for discoloration. If plate surface is smooth and even color smear is indicated, the plate should be reused. If severe heat spot discoloration or surface scuffing is indicated, the plate must be replaced.
3. Clutch Release Springs
Evidence of extreme heat or burning in the area of clutch may have caused springs to take a heat set and would require their replacement.
CAUSES OF BURNED CLUTCH PLATES
1. Second Clutch, Third Clutch or Reverse Clutch
- Stuck or missing of check ball in clutch.
- Damaged or missing of clutch piston seals.
- Low line pressure.
- Oil pump seal rings missing, broken or worn out.
2. Low Band
- Servo piston seals damaged or missing
- Low Line pressure.
3. Valve Body or Case
Case or valve body face not flat or porosity between channels.
Engine coolant in transmission fluid can cause severe damage, such as large pieces of clutch plate lining peeling off.
COOLER LINE FLUSHING
In a major transmission failure, where particles of metal have been carried with the fluid throughout the units of transmission, it will be necessary to flush out oil cooler and connecting lines as well.